24 files changed, 12464 insertions, 0 deletions

diff --git a/crates/ra_hir_ty/src/autoderef.rs b/crates/ra_hir_ty/src/autoderef.rs
new file mode 100644
index 000000000..9d1d4e48c
--- /dev/null
+++ b/crates/ra_hir_ty/src/autoderef.rs
@@ -0,0 +1,108 @@
+//! In certain situations, rust automatically inserts derefs as necessary: for
+//! example, field accesses `foo.bar` still work when `foo` is actually a
+//! reference to a type with the field `bar`. This is an approximation of the
+//! logic in rustc (which lives in librustc_typeck/check/autoderef.rs).
+
+use std::iter::successors;
+
+use hir_def::lang_item::LangItemTarget;
+use hir_expand::name;
+use log::{info, warn};
+use ra_db::CrateId;
+
+use crate::db::HirDatabase;
+
+use super::{
+    traits::{InEnvironment, Solution},
+    Canonical, Substs, Ty, TypeWalk,
+};
+
+const AUTODEREF_RECURSION_LIMIT: usize = 10;
+
+pub fn autoderef<'a>(
+    db: &'a impl HirDatabase,
+    krate: Option<CrateId>,
+    ty: InEnvironment<Canonical<Ty>>,
+) -> impl Iterator<Item = Canonical<Ty>> + 'a {
+    let InEnvironment { value: ty, environment } = ty;
+    successors(Some(ty), move |ty| {
+        deref(db, krate?, InEnvironment { value: ty, environment: environment.clone() })
+    })
+    .take(AUTODEREF_RECURSION_LIMIT)
+}
+
+pub(crate) fn deref(
+    db: &impl HirDatabase,
+    krate: CrateId,
+    ty: InEnvironment<&Canonical<Ty>>,
+) -> Option<Canonical<Ty>> {
+    if let Some(derefed) = ty.value.value.builtin_deref() {
+        Some(Canonical { value: derefed, num_vars: ty.value.num_vars })
+    } else {
+        deref_by_trait(db, krate, ty)
+    }
+}
+
+fn deref_by_trait(
+    db: &impl HirDatabase,
+    krate: CrateId,
+    ty: InEnvironment<&Canonical<Ty>>,
+) -> Option<Canonical<Ty>> {
+    let deref_trait = match db.lang_item(krate.into(), "deref".into())? {
+        LangItemTarget::TraitId(it) => it,
+        _ => return None,
+    };
+    let target = db.trait_data(deref_trait).associated_type_by_name(&name::TARGET_TYPE)?;
+
+    let generic_params = db.generic_params(target.into());
+    if generic_params.count_params_including_parent() != 1 {
+        // the Target type + Deref trait should only have one generic parameter,
+        // namely Deref's Self type
+        return None;
+    }
+
+    // FIXME make the Canonical handling nicer
+
+    let parameters = Substs::build_for_generics(&generic_params)
+        .push(ty.value.value.clone().shift_bound_vars(1))
+        .build();
+
+    let projection = super::traits::ProjectionPredicate {
+        ty: Ty::Bound(0),
+        projection_ty: super::ProjectionTy { associated_ty: target, parameters },
+    };
+
+    let obligation = super::Obligation::Projection(projection);
+
+    let in_env = InEnvironment { value: obligation, environment: ty.environment };
+
+    let canonical = super::Canonical { num_vars: 1 + ty.value.num_vars, value: in_env };
+
+    let solution = db.trait_solve(krate.into(), canonical)?;
+
+    match &solution {
+        Solution::Unique(vars) => {
+            // FIXME: vars may contain solutions for any inference variables
+            // that happened to be inside ty. To correctly handle these, we
+            // would have to pass the solution up to the inference context, but
+            // that requires a larger refactoring (especially if the deref
+            // happens during method resolution). So for the moment, we just
+            // check that we're not in the situation we're we would actually
+            // need to handle the values of the additional variables, i.e.
+            // they're just being 'passed through'. In the 'standard' case where
+            // we have `impl<T> Deref for Foo<T> { Target = T }`, that should be
+            // the case.
+            for i in 1..vars.0.num_vars {
+                if vars.0.value[i] != Ty::Bound((i - 1) as u32) {
+                    warn!("complex solution for derefing {:?}: {:?}, ignoring", ty.value, solution);
+                    return None;
+                }
+            }
+            Some(Canonical { value: vars.0.value[0].clone(), num_vars: vars.0.num_vars })
+        }
+        Solution::Ambig(_) => {
+            info!("Ambiguous solution for derefing {:?}: {:?}", ty.value, solution);
+            None
+        }
+    }
+}
diff --git a/crates/ra_hir_ty/src/db.rs b/crates/ra_hir_ty/src/db.rs
new file mode 100644
index 000000000..9ce154593
--- /dev/null
+++ b/crates/ra_hir_ty/src/db.rs
@@ -0,0 +1,119 @@
+//! FIXME: write short doc here
+
+use std::sync::Arc;
+
+use hir_def::{
+    db::DefDatabase, DefWithBodyId, GenericDefId, ImplId, LocalStructFieldId, TraitId, VariantId,
+};
+use ra_arena::map::ArenaMap;
+use ra_db::{salsa, CrateId};
+
+use crate::{
+    method_resolution::CrateImplBlocks,
+    traits::{AssocTyValue, Impl},
+    CallableDef, FnSig, GenericPredicate, ImplTy, InferenceResult, Substs, Ty, TyDefId, TypeCtor,
+    ValueTyDefId,
+};
+
+#[salsa::query_group(HirDatabaseStorage)]
+#[salsa::requires(salsa::Database)]
+pub trait HirDatabase: DefDatabase {
+    #[salsa::invoke(crate::infer_query)]
+    fn infer(&self, def: DefWithBodyId) -> Arc<InferenceResult>;
+
+    #[salsa::invoke(crate::lower::ty_query)]
+    fn ty(&self, def: TyDefId) -> Ty;
+
+    #[salsa::invoke(crate::lower::value_ty_query)]
+    fn value_ty(&self, def: ValueTyDefId) -> Ty;
+
+    #[salsa::invoke(crate::lower::impl_ty_query)]
+    fn impl_ty(&self, def: ImplId) -> ImplTy;
+
+    #[salsa::invoke(crate::lower::field_types_query)]
+    fn field_types(&self, var: VariantId) -> Arc<ArenaMap<LocalStructFieldId, Ty>>;
+
+    #[salsa::invoke(crate::callable_item_sig)]
+    fn callable_item_signature(&self, def: CallableDef) -> FnSig;
+
+    #[salsa::invoke(crate::lower::generic_predicates_for_param_query)]
+    fn generic_predicates_for_param(
+        &self,
+        def: GenericDefId,
+        param_idx: u32,
+    ) -> Arc<[GenericPredicate]>;
+
+    #[salsa::invoke(crate::lower::generic_predicates_query)]
+    fn generic_predicates(&self, def: GenericDefId) -> Arc<[GenericPredicate]>;
+
+    #[salsa::invoke(crate::lower::generic_defaults_query)]
+    fn generic_defaults(&self, def: GenericDefId) -> Substs;
+
+    #[salsa::invoke(crate::method_resolution::CrateImplBlocks::impls_in_crate_query)]
+    fn impls_in_crate(&self, krate: CrateId) -> Arc<CrateImplBlocks>;
+
+    #[salsa::invoke(crate::traits::impls_for_trait_query)]
+    fn impls_for_trait(&self, krate: CrateId, trait_: TraitId) -> Arc<[ImplId]>;
+
+    /// This provides the Chalk trait solver instance. Because Chalk always
+    /// works from a specific crate, this query is keyed on the crate; and
+    /// because Chalk does its own internal caching, the solver is wrapped in a
+    /// Mutex and the query does an untracked read internally, to make sure the
+    /// cached state is thrown away when input facts change.
+    #[salsa::invoke(crate::traits::trait_solver_query)]
+    fn trait_solver(&self, krate: CrateId) -> crate::traits::TraitSolver;
+
+    // Interned IDs for Chalk integration
+    #[salsa::interned]
+    fn intern_type_ctor(&self, type_ctor: TypeCtor) -> crate::TypeCtorId;
+    #[salsa::interned]
+    fn intern_chalk_impl(&self, impl_: Impl) -> crate::traits::GlobalImplId;
+    #[salsa::interned]
+    fn intern_assoc_ty_value(&self, assoc_ty_value: AssocTyValue) -> crate::traits::AssocTyValueId;
+
+    #[salsa::invoke(crate::traits::chalk::associated_ty_data_query)]
+    fn associated_ty_data(
+        &self,
+        id: chalk_ir::TypeId,
+    ) -> Arc<chalk_rust_ir::AssociatedTyDatum<chalk_ir::family::ChalkIr>>;
+
+    #[salsa::invoke(crate::traits::chalk::trait_datum_query)]
+    fn trait_datum(
+        &self,
+        krate: CrateId,
+        trait_id: chalk_ir::TraitId,
+    ) -> Arc<chalk_rust_ir::TraitDatum<chalk_ir::family::ChalkIr>>;
+
+    #[salsa::invoke(crate::traits::chalk::struct_datum_query)]
+    fn struct_datum(
+        &self,
+        krate: CrateId,
+        struct_id: chalk_ir::StructId,
+    ) -> Arc<chalk_rust_ir::StructDatum<chalk_ir::family::ChalkIr>>;
+
+    #[salsa::invoke(crate::traits::chalk::impl_datum_query)]
+    fn impl_datum(
+        &self,
+        krate: CrateId,
+        impl_id: chalk_ir::ImplId,
+    ) -> Arc<chalk_rust_ir::ImplDatum<chalk_ir::family::ChalkIr>>;
+
+    #[salsa::invoke(crate::traits::chalk::associated_ty_value_query)]
+    fn associated_ty_value(
+        &self,
+        krate: CrateId,
+        id: chalk_rust_ir::AssociatedTyValueId,
+    ) -> Arc<chalk_rust_ir::AssociatedTyValue<chalk_ir::family::ChalkIr>>;
+
+    #[salsa::invoke(crate::traits::trait_solve_query)]
+    fn trait_solve(
+        &self,
+        krate: CrateId,
+        goal: crate::Canonical<crate::InEnvironment<crate::Obligation>>,
+    ) -> Option<crate::traits::Solution>;
+}
+
+#[test]
+fn hir_database_is_object_safe() {
+    fn _assert_object_safe(_: &dyn HirDatabase) {}
+}
diff --git a/crates/ra_hir_ty/src/diagnostics.rs b/crates/ra_hir_ty/src/diagnostics.rs
new file mode 100644
index 000000000..4a13fac23
--- /dev/null
+++ b/crates/ra_hir_ty/src/diagnostics.rs
@@ -0,0 +1,91 @@
+//! FIXME: write short doc here
+
+use std::any::Any;
+
+use hir_expand::{db::AstDatabase, name::Name, HirFileId, Source};
+use ra_syntax::{ast, AstNode, AstPtr, SyntaxNodePtr};
+
+pub use hir_def::diagnostics::UnresolvedModule;
+pub use hir_expand::diagnostics::{AstDiagnostic, Diagnostic, DiagnosticSink};
+
+#[derive(Debug)]
+pub struct NoSuchField {
+    pub file: HirFileId,
+    pub field: AstPtr<ast::RecordField>,
+}
+
+impl Diagnostic for NoSuchField {
+    fn message(&self) -> String {
+        "no such field".to_string()
+    }
+
+    fn source(&self) -> Source<SyntaxNodePtr> {
+        Source { file_id: self.file, value: self.field.into() }
+    }
+
+    fn as_any(&self) -> &(dyn Any + Send + 'static) {
+        self
+    }
+}
+
+#[derive(Debug)]
+pub struct MissingFields {
+    pub file: HirFileId,
+    pub field_list: AstPtr<ast::RecordFieldList>,
+    pub missed_fields: Vec<Name>,
+}
+
+impl Diagnostic for MissingFields {
+    fn message(&self) -> String {
+        use std::fmt::Write;
+        let mut message = String::from("Missing structure fields:\n");
+        for field in &self.missed_fields {
+            write!(message, "- {}\n", field).unwrap();
+        }
+        message
+    }
+    fn source(&self) -> Source<SyntaxNodePtr> {
+        Source { file_id: self.file, value: self.field_list.into() }
+    }
+    fn as_any(&self) -> &(dyn Any + Send + 'static) {
+        self
+    }
+}
+
+impl AstDiagnostic for MissingFields {
+    type AST = ast::RecordFieldList;
+
+    fn ast(&self, db: &impl AstDatabase) -> Self::AST {
+        let root = db.parse_or_expand(self.source().file_id).unwrap();
+        let node = self.source().value.to_node(&root);
+        ast::RecordFieldList::cast(node).unwrap()
+    }
+}
+
+#[derive(Debug)]
+pub struct MissingOkInTailExpr {
+    pub file: HirFileId,
+    pub expr: AstPtr<ast::Expr>,
+}
+
+impl Diagnostic for MissingOkInTailExpr {
+    fn message(&self) -> String {
+        "wrap return expression in Ok".to_string()
+    }
+    fn source(&self) -> Source<SyntaxNodePtr> {
+        Source { file_id: self.file, value: self.expr.into() }
+    }
+    fn as_any(&self) -> &(dyn Any + Send + 'static) {
+        self
+    }
+}
+
+impl AstDiagnostic for MissingOkInTailExpr {
+    type AST = ast::Expr;
+
+    fn ast(&self, db: &impl AstDatabase) -> Self::AST {
+        let root = db.parse_or_expand(self.file).unwrap();
+        let node = self.source().value.to_node(&root);
+        ast::Expr::cast(node).unwrap()
+    }
+}
diff --git a/crates/ra_hir_ty/src/display.rs b/crates/ra_hir_ty/src/display.rs
new file mode 100644
index 000000000..9bb3ece6c
--- /dev/null
+++ b/crates/ra_hir_ty/src/display.rs
@@ -0,0 +1,93 @@
+//! FIXME: write short doc here
+
+use std::fmt;
+
+use crate::db::HirDatabase;
+
+pub struct HirFormatter<'a, 'b, DB> {
+    pub db: &'a DB,
+    fmt: &'a mut fmt::Formatter<'b>,
+    buf: String,
+    curr_size: usize,
+    max_size: Option<usize>,
+}
+
+pub trait HirDisplay {
+    fn hir_fmt(&self, f: &mut HirFormatter<impl HirDatabase>) -> fmt::Result;
+
+    fn display<'a, DB>(&'a self, db: &'a DB) -> HirDisplayWrapper<'a, DB, Self>
+    where
+        Self: Sized,
+    {
+        HirDisplayWrapper(db, self, None)
+    }
+
+    fn display_truncated<'a, DB>(
+        &'a self,
+        db: &'a DB,
+        max_size: Option<usize>,
+    ) -> HirDisplayWrapper<'a, DB, Self>
+    where
+        Self: Sized,
+    {
+        HirDisplayWrapper(db, self, max_size)
+    }
+}
+
+impl<'a, 'b, DB> HirFormatter<'a, 'b, DB>
+where
+    DB: HirDatabase,
+{
+    pub fn write_joined<T: HirDisplay>(
+        &mut self,
+        iter: impl IntoIterator<Item = T>,
+        sep: &str,
+    ) -> fmt::Result {
+        let mut first = true;
+        for e in iter {
+            if !first {
+                write!(self, "{}", sep)?;
+            }
+            first = false;
+            e.hir_fmt(self)?;
+        }
+        Ok(())
+    }
+
+    /// This allows using the `write!` macro directly with a `HirFormatter`.
+    pub fn write_fmt(&mut self, args: fmt::Arguments) -> fmt::Result {
+        // We write to a buffer first to track output size
+        self.buf.clear();
+        fmt::write(&mut self.buf, args)?;
+        self.curr_size += self.buf.len();
+
+        // Then we write to the internal formatter from the buffer
+        self.fmt.write_str(&self.buf)
+    }
+
+    pub fn should_truncate(&self) -> bool {
+        if let Some(max_size) = self.max_size {
+            self.curr_size >= max_size
+        } else {
+            false
+        }
+    }
+}
+
+pub struct HirDisplayWrapper<'a, DB, T>(&'a DB, &'a T, Option<usize>);
+
+impl<'a, DB, T> fmt::Display for HirDisplayWrapper<'a, DB, T>
+where
+    DB: HirDatabase,
+    T: HirDisplay,
+{
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        self.1.hir_fmt(&mut HirFormatter {
+            db: self.0,
+            fmt: f,
+            buf: String::with_capacity(20),
+            curr_size: 0,
+            max_size: self.2,
+        })
+    }
+}
diff --git a/crates/ra_hir_ty/src/expr.rs b/crates/ra_hir_ty/src/expr.rs
new file mode 100644
index 000000000..5c65f9370
--- /dev/null
+++ b/crates/ra_hir_ty/src/expr.rs
@@ -0,0 +1,151 @@
+//! FIXME: write short doc here
+
+use std::sync::Arc;
+
+use hir_def::{
+    path::{known, Path},
+    resolver::HasResolver,
+    AdtId, FunctionId,
+};
+use hir_expand::{diagnostics::DiagnosticSink, name::Name};
+use ra_syntax::ast;
+use ra_syntax::AstPtr;
+use rustc_hash::FxHashSet;
+
+use crate::{
+    db::HirDatabase,
+    diagnostics::{MissingFields, MissingOkInTailExpr},
+    ApplicationTy, InferenceResult, Ty, TypeCtor,
+};
+
+pub use hir_def::{
+    body::{
+        scope::{ExprScopes, ScopeEntry, ScopeId},
+        Body, BodySourceMap, ExprPtr, ExprSource, PatPtr, PatSource,
+    },
+    expr::{
+        ArithOp, Array, BinaryOp, BindingAnnotation, CmpOp, Expr, ExprId, Literal, LogicOp,
+        MatchArm, Ordering, Pat, PatId, RecordFieldPat, RecordLitField, Statement, UnaryOp,
+    },
+};
+
+pub struct ExprValidator<'a, 'b: 'a> {
+    func: FunctionId,
+    infer: Arc<InferenceResult>,
+    sink: &'a mut DiagnosticSink<'b>,
+}
+
+impl<'a, 'b> ExprValidator<'a, 'b> {
+    pub fn new(
+        func: FunctionId,
+        infer: Arc<InferenceResult>,
+        sink: &'a mut DiagnosticSink<'b>,
+    ) -> ExprValidator<'a, 'b> {
+        ExprValidator { func, infer, sink }
+    }
+
+    pub fn validate_body(&mut self, db: &impl HirDatabase) {
+        let body = db.body(self.func.into());
+
+        for e in body.exprs.iter() {
+            if let (id, Expr::RecordLit { path, fields, spread }) = e {
+                self.validate_record_literal(id, path, fields, *spread, db);
+            }
+        }
+
+        let body_expr = &body[body.body_expr];
+        if let Expr::Block { statements: _, tail: Some(t) } = body_expr {
+            self.validate_results_in_tail_expr(body.body_expr, *t, db);
+        }
+    }
+
+    fn validate_record_literal(
+        &mut self,
+        id: ExprId,
+        _path: &Option<Path>,
+        fields: &[RecordLitField],
+        spread: Option<ExprId>,
+        db: &impl HirDatabase,
+    ) {
+        if spread.is_some() {
+            return;
+        }
+
+        let struct_def = match self.infer[id].as_adt() {
+            Some((AdtId::StructId(s), _)) => s,
+            _ => return,
+        };
+        let struct_data = db.struct_data(struct_def);
+
+        let lit_fields: FxHashSet<_> = fields.iter().map(|f| &f.name).collect();
+        let missed_fields: Vec<Name> = struct_data
+            .variant_data
+            .fields()
+            .iter()
+            .filter_map(|(_f, d)| {
+                let name = d.name.clone();
+                if lit_fields.contains(&name) {
+                    None
+                } else {
+                    Some(name)
+                }
+            })
+            .collect();
+        if missed_fields.is_empty() {
+            return;
+        }
+        let (_, source_map) = db.body_with_source_map(self.func.into());
+
+        if let Some(source_ptr) = source_map.expr_syntax(id) {
+            if let Some(expr) = source_ptr.value.a() {
+                let root = source_ptr.file_syntax(db);
+                if let ast::Expr::RecordLit(record_lit) = expr.to_node(&root) {
+                    if let Some(field_list) = record_lit.record_field_list() {
+                        self.sink.push(MissingFields {
+                            file: source_ptr.file_id,
+                            field_list: AstPtr::new(&field_list),
+                            missed_fields,
+                        })
+                    }
+                }
+            }
+        }
+    }
+
+    fn validate_results_in_tail_expr(
+        &mut self,
+        body_id: ExprId,
+        id: ExprId,
+        db: &impl HirDatabase,
+    ) {
+        // the mismatch will be on the whole block currently
+        let mismatch = match self.infer.type_mismatch_for_expr(body_id) {
+            Some(m) => m,
+            None => return,
+        };
+
+        let std_result_path = known::std_result_result();
+
+        let resolver = self.func.resolver(db);
+        let std_result_enum = match resolver.resolve_known_enum(db, &std_result_path) {
+            Some(it) => it,
+            _ => return,
+        };
+
+        let std_result_ctor = TypeCtor::Adt(AdtId::EnumId(std_result_enum));
+        let params = match &mismatch.expected {
+            Ty::Apply(ApplicationTy { ctor, parameters }) if ctor == &std_result_ctor => parameters,
+            _ => return,
+        };
+
+        if params.len() == 2 && &params[0] == &mismatch.actual {
+            let (_, source_map) = db.body_with_source_map(self.func.into());
+
+            if let Some(source_ptr) = source_map.expr_syntax(id) {
+                if let Some(expr) = source_ptr.value.a() {
+                    self.sink.push(MissingOkInTailExpr { file: source_ptr.file_id, expr });
+                }
+            }
+        }
+    }
+}
diff --git a/crates/ra_hir_ty/src/infer.rs b/crates/ra_hir_ty/src/infer.rs
new file mode 100644
index 000000000..1e9f4b208
--- /dev/null
+++ b/crates/ra_hir_ty/src/infer.rs
@@ -0,0 +1,723 @@
+//! Type inference, i.e. the process of walking through the code and determining
+//! the type of each expression and pattern.
+//!
+//! For type inference, compare the implementations in rustc (the various
+//! check_* methods in librustc_typeck/check/mod.rs are a good entry point) and
+//! IntelliJ-Rust (org.rust.lang.core.types.infer). Our entry point for
+//! inference here is the `infer` function, which infers the types of all
+//! expressions in a given function.
+//!
+//! During inference, types (i.e. the `Ty` struct) can contain type 'variables'
+//! which represent currently unknown types; as we walk through the expressions,
+//! we might determine that certain variables need to be equal to each other, or
+//! to certain types. To record this, we use the union-find implementation from
+//! the `ena` crate, which is extracted from rustc.
+
+use std::borrow::Cow;
+use std::mem;
+use std::ops::Index;
+use std::sync::Arc;
+
+use ena::unify::{InPlaceUnificationTable, NoError, UnifyKey, UnifyValue};
+use rustc_hash::FxHashMap;
+
+use hir_def::{
+    body::Body,
+    data::{ConstData, FunctionData},
+    expr::{BindingAnnotation, ExprId, PatId},
+    path::{known, Path},
+    resolver::{HasResolver, Resolver, TypeNs},
+    type_ref::{Mutability, TypeRef},
+    AdtId, AssocItemId, DefWithBodyId, FunctionId, StructFieldId, TypeAliasId, VariantId,
+};
+use hir_expand::{diagnostics::DiagnosticSink, name};
+use ra_arena::map::ArenaMap;
+use ra_prof::profile;
+use test_utils::tested_by;
+
+use super::{
+    primitive::{FloatTy, IntTy},
+    traits::{Guidance, Obligation, ProjectionPredicate, Solution},
+    ApplicationTy, InEnvironment, ProjectionTy, Substs, TraitEnvironment, TraitRef, Ty, TypeCtor,
+    TypeWalk, Uncertain,
+};
+use crate::{db::HirDatabase, infer::diagnostics::InferenceDiagnostic};
+
+macro_rules! ty_app {
+    ($ctor:pat, $param:pat) => {
+        crate::Ty::Apply(crate::ApplicationTy { ctor: $ctor, parameters: $param })
+    };
+    ($ctor:pat) => {
+        ty_app!($ctor, _)
+    };
+}
+
+mod unify;
+mod path;
+mod expr;
+mod pat;
+mod coerce;
+
+/// The entry point of type inference.
+pub fn infer_query(db: &impl HirDatabase, def: DefWithBodyId) -> Arc<InferenceResult> {
+    let _p = profile("infer_query");
+    let resolver = def.resolver(db);
+    let mut ctx = InferenceContext::new(db, def, resolver);
+
+    match def {
+        DefWithBodyId::ConstId(c) => ctx.collect_const(&db.const_data(c)),
+        DefWithBodyId::FunctionId(f) => ctx.collect_fn(&db.function_data(f)),
+        DefWithBodyId::StaticId(s) => ctx.collect_const(&db.static_data(s)),
+    }
+
+    ctx.infer_body();
+
+    Arc::new(ctx.resolve_all())
+}
+
+#[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
+enum ExprOrPatId {
+    ExprId(ExprId),
+    PatId(PatId),
+}
+
+impl_froms!(ExprOrPatId: ExprId, PatId);
+
+/// Binding modes inferred for patterns.
+/// https://doc.rust-lang.org/reference/patterns.html#binding-modes
+#[derive(Copy, Clone, Debug, Eq, PartialEq)]
+enum BindingMode {
+    Move,
+    Ref(Mutability),
+}
+
+impl BindingMode {
+    pub fn convert(annotation: BindingAnnotation) -> BindingMode {
+        match annotation {
+            BindingAnnotation::Unannotated | BindingAnnotation::Mutable => BindingMode::Move,
+            BindingAnnotation::Ref => BindingMode::Ref(Mutability::Shared),
+            BindingAnnotation::RefMut => BindingMode::Ref(Mutability::Mut),
+        }
+    }
+}
+
+impl Default for BindingMode {
+    fn default() -> Self {
+        BindingMode::Move
+    }
+}
+
+/// A mismatch between an expected and an inferred type.
+#[derive(Clone, PartialEq, Eq, Debug, Hash)]
+pub struct TypeMismatch {
+    pub expected: Ty,
+    pub actual: Ty,
+}
+
+/// The result of type inference: A mapping from expressions and patterns to types.
+#[derive(Clone, PartialEq, Eq, Debug, Default)]
+pub struct InferenceResult {
+    /// For each method call expr, records the function it resolves to.
+    method_resolutions: FxHashMap<ExprId, FunctionId>,
+    /// For each field access expr, records the field it resolves to.
+    field_resolutions: FxHashMap<ExprId, StructFieldId>,
+    /// For each field in record literal, records the field it resolves to.
+    record_field_resolutions: FxHashMap<ExprId, StructFieldId>,
+    /// For each struct literal, records the variant it resolves to.
+    variant_resolutions: FxHashMap<ExprOrPatId, VariantId>,
+    /// For each associated item record what it resolves to
+    assoc_resolutions: FxHashMap<ExprOrPatId, AssocItemId>,
+    diagnostics: Vec<InferenceDiagnostic>,
+    pub type_of_expr: ArenaMap<ExprId, Ty>,
+    pub type_of_pat: ArenaMap<PatId, Ty>,
+    pub(super) type_mismatches: ArenaMap<ExprId, TypeMismatch>,
+}
+
+impl InferenceResult {
+    pub fn method_resolution(&self, expr: ExprId) -> Option<FunctionId> {
+        self.method_resolutions.get(&expr).copied()
+    }
+    pub fn field_resolution(&self, expr: ExprId) -> Option<StructFieldId> {
+        self.field_resolutions.get(&expr).copied()
+    }
+    pub fn record_field_resolution(&self, expr: ExprId) -> Option<StructFieldId> {
+        self.record_field_resolutions.get(&expr).copied()
+    }
+    pub fn variant_resolution_for_expr(&self, id: ExprId) -> Option<VariantId> {
+        self.variant_resolutions.get(&id.into()).copied()
+    }
+    pub fn variant_resolution_for_pat(&self, id: PatId) -> Option<VariantId> {
+        self.variant_resolutions.get(&id.into()).copied()
+    }
+    pub fn assoc_resolutions_for_expr(&self, id: ExprId) -> Option<AssocItemId> {
+        self.assoc_resolutions.get(&id.into()).copied()
+    }
+    pub fn assoc_resolutions_for_pat(&self, id: PatId) -> Option<AssocItemId> {
+        self.assoc_resolutions.get(&id.into()).copied()
+    }
+    pub fn type_mismatch_for_expr(&self, expr: ExprId) -> Option<&TypeMismatch> {
+        self.type_mismatches.get(expr)
+    }
+    pub fn add_diagnostics(
+        &self,
+        db: &impl HirDatabase,
+        owner: FunctionId,
+        sink: &mut DiagnosticSink,
+    ) {
+        self.diagnostics.iter().for_each(|it| it.add_to(db, owner, sink))
+    }
+}
+
+impl Index<ExprId> for InferenceResult {
+    type Output = Ty;
+
+    fn index(&self, expr: ExprId) -> &Ty {
+        self.type_of_expr.get(expr).unwrap_or(&Ty::Unknown)
+    }
+}
+
+impl Index<PatId> for InferenceResult {
+    type Output = Ty;
+
+    fn index(&self, pat: PatId) -> &Ty {
+        self.type_of_pat.get(pat).unwrap_or(&Ty::Unknown)
+    }
+}
+
+/// The inference context contains all information needed during type inference.
+#[derive(Clone, Debug)]
+struct InferenceContext<'a, D: HirDatabase> {
+    db: &'a D,
+    owner: DefWithBodyId,
+    body: Arc<Body>,
+    resolver: Resolver,
+    var_unification_table: InPlaceUnificationTable<TypeVarId>,
+    trait_env: Arc<TraitEnvironment>,
+    obligations: Vec<Obligation>,
+    result: InferenceResult,
+    /// The return type of the function being inferred.
+    return_ty: Ty,
+
+    /// Impls of `CoerceUnsized` used in coercion.
+    /// (from_ty_ctor, to_ty_ctor) => coerce_generic_index
+    // FIXME: Use trait solver for this.
+    // Chalk seems unable to work well with builtin impl of `Unsize` now.
+    coerce_unsized_map: FxHashMap<(TypeCtor, TypeCtor), usize>,
+}
+
+impl<'a, D: HirDatabase> InferenceContext<'a, D> {
+    fn new(db: &'a D, owner: DefWithBodyId, resolver: Resolver) -> Self {
+        InferenceContext {
+            result: InferenceResult::default(),
+            var_unification_table: InPlaceUnificationTable::new(),
+            obligations: Vec::default(),
+            return_ty: Ty::Unknown, // set in collect_fn_signature
+            trait_env: TraitEnvironment::lower(db, &resolver),
+            coerce_unsized_map: Self::init_coerce_unsized_map(db, &resolver),
+            db,
+            owner,
+            body: db.body(owner.into()),
+            resolver,
+        }
+    }
+
+    fn resolve_all(mut self) -> InferenceResult {
+        // FIXME resolve obligations as well (use Guidance if necessary)
+        let mut result = mem::replace(&mut self.result, InferenceResult::default());
+        let mut tv_stack = Vec::new();
+        for ty in result.type_of_expr.values_mut() {
+            let resolved = self.resolve_ty_completely(&mut tv_stack, mem::replace(ty, Ty::Unknown));
+            *ty = resolved;
+        }
+        for ty in result.type_of_pat.values_mut() {
+            let resolved = self.resolve_ty_completely(&mut tv_stack, mem::replace(ty, Ty::Unknown));
+            *ty = resolved;
+        }
+        result
+    }
+
+    fn write_expr_ty(&mut self, expr: ExprId, ty: Ty) {
+        self.result.type_of_expr.insert(expr, ty);
+    }
+
+    fn write_method_resolution(&mut self, expr: ExprId, func: FunctionId) {
+        self.result.method_resolutions.insert(expr, func);
+    }
+
+    fn write_field_resolution(&mut self, expr: ExprId, field: StructFieldId) {
+        self.result.field_resolutions.insert(expr, field);
+    }
+
+    fn write_variant_resolution(&mut self, id: ExprOrPatId, variant: VariantId) {
+        self.result.variant_resolutions.insert(id, variant);
+    }
+
+    fn write_assoc_resolution(&mut self, id: ExprOrPatId, item: AssocItemId) {
+        self.result.assoc_resolutions.insert(id, item.into());
+    }
+
+    fn write_pat_ty(&mut self, pat: PatId, ty: Ty) {
+        self.result.type_of_pat.insert(pat, ty);
+    }
+
+    fn push_diagnostic(&mut self, diagnostic: InferenceDiagnostic) {
+        self.result.diagnostics.push(diagnostic);
+    }
+
+    fn make_ty(&mut self, type_ref: &TypeRef) -> Ty {
+        let ty = Ty::from_hir(
+            self.db,
+            // FIXME use right resolver for block
+            &self.resolver,
+            type_ref,
+        );
+        let ty = self.insert_type_vars(ty);
+        self.normalize_associated_types_in(ty)
+    }
+
+    fn unify_substs(&mut self, substs1: &Substs, substs2: &Substs, depth: usize) -> bool {
+        substs1.0.iter().zip(substs2.0.iter()).all(|(t1, t2)| self.unify_inner(t1, t2, depth))
+    }
+
+    fn unify(&mut self, ty1: &Ty, ty2: &Ty) -> bool {
+        self.unify_inner(ty1, ty2, 0)
+    }
+
+    fn unify_inner(&mut self, ty1: &Ty, ty2: &Ty, depth: usize) -> bool {
+        if depth > 1000 {
+            // prevent stackoverflows
+            panic!("infinite recursion in unification");
+        }
+        if ty1 == ty2 {
+            return true;
+        }
+        // try to resolve type vars first
+        let ty1 = self.resolve_ty_shallow(ty1);
+        let ty2 = self.resolve_ty_shallow(ty2);
+        match (&*ty1, &*ty2) {
+            (Ty::Apply(a_ty1), Ty::Apply(a_ty2)) if a_ty1.ctor == a_ty2.ctor => {
+                self.unify_substs(&a_ty1.parameters, &a_ty2.parameters, depth + 1)
+            }
+            _ => self.unify_inner_trivial(&ty1, &ty2),
+        }
+    }
+
+    fn unify_inner_trivial(&mut self, ty1: &Ty, ty2: &Ty) -> bool {
+        match (ty1, ty2) {
+            (Ty::Unknown, _) | (_, Ty::Unknown) => true,
+
+            (Ty::Infer(InferTy::TypeVar(tv1)), Ty::Infer(InferTy::TypeVar(tv2)))
+            | (Ty::Infer(InferTy::IntVar(tv1)), Ty::Infer(InferTy::IntVar(tv2)))
+            | (Ty::Infer(InferTy::FloatVar(tv1)), Ty::Infer(InferTy::FloatVar(tv2)))
+            | (
+                Ty::Infer(InferTy::MaybeNeverTypeVar(tv1)),
+                Ty::Infer(InferTy::MaybeNeverTypeVar(tv2)),
+            ) => {
+                // both type vars are unknown since we tried to resolve them
+                self.var_unification_table.union(*tv1, *tv2);
+                true
+            }
+
+            // The order of MaybeNeverTypeVar matters here.
+            // Unifying MaybeNeverTypeVar and TypeVar will let the latter become MaybeNeverTypeVar.
+            // Unifying MaybeNeverTypeVar and other concrete type will let the former become it.
+            (Ty::Infer(InferTy::TypeVar(tv)), other)
+            | (other, Ty::Infer(InferTy::TypeVar(tv)))
+            | (Ty::Infer(InferTy::MaybeNeverTypeVar(tv)), other)
+            | (other, Ty::Infer(InferTy::MaybeNeverTypeVar(tv)))
+            | (Ty::Infer(InferTy::IntVar(tv)), other @ ty_app!(TypeCtor::Int(_)))
+            | (other @ ty_app!(TypeCtor::Int(_)), Ty::Infer(InferTy::IntVar(tv)))
+            | (Ty::Infer(InferTy::FloatVar(tv)), other @ ty_app!(TypeCtor::Float(_)))
+            | (other @ ty_app!(TypeCtor::Float(_)), Ty::Infer(InferTy::FloatVar(tv))) => {
+                // the type var is unknown since we tried to resolve it
+                self.var_unification_table.union_value(*tv, TypeVarValue::Known(other.clone()));
+                true
+            }
+
+            _ => false,
+        }
+    }
+
+    fn new_type_var(&mut self) -> Ty {
+        Ty::Infer(InferTy::TypeVar(self.var_unification_table.new_key(TypeVarValue::Unknown)))
+    }
+
+    fn new_integer_var(&mut self) -> Ty {
+        Ty::Infer(InferTy::IntVar(self.var_unification_table.new_key(TypeVarValue::Unknown)))
+    }
+
+    fn new_float_var(&mut self) -> Ty {
+        Ty::Infer(InferTy::FloatVar(self.var_unification_table.new_key(TypeVarValue::Unknown)))
+    }
+
+    fn new_maybe_never_type_var(&mut self) -> Ty {
+        Ty::Infer(InferTy::MaybeNeverTypeVar(
+            self.var_unification_table.new_key(TypeVarValue::Unknown),
+        ))
+    }
+
+    /// Replaces Ty::Unknown by a new type var, so we can maybe still infer it.
+    fn insert_type_vars_shallow(&mut self, ty: Ty) -> Ty {
+        match ty {
+            Ty::Unknown => self.new_type_var(),
+            Ty::Apply(ApplicationTy { ctor: TypeCtor::Int(Uncertain::Unknown), .. }) => {
+                self.new_integer_var()
+            }
+            Ty::Apply(ApplicationTy { ctor: TypeCtor::Float(Uncertain::Unknown), .. }) => {
+                self.new_float_var()
+            }
+            _ => ty,
+        }
+    }
+
+    fn insert_type_vars(&mut self, ty: Ty) -> Ty {
+        ty.fold(&mut |ty| self.insert_type_vars_shallow(ty))
+    }
+
+    fn resolve_obligations_as_possible(&mut self) {
+        let obligations = mem::replace(&mut self.obligations, Vec::new());
+        for obligation in obligations {
+            let in_env = InEnvironment::new(self.trait_env.clone(), obligation.clone());
+            let canonicalized = self.canonicalizer().canonicalize_obligation(in_env);
+            let solution = self
+                .db
+                .trait_solve(self.resolver.krate().unwrap().into(), canonicalized.value.clone());
+
+            match solution {
+                Some(Solution::Unique(substs)) => {
+                    canonicalized.apply_solution(self, substs.0);
+                }
+                Some(Solution::Ambig(Guidance::Definite(substs))) => {
+                    canonicalized.apply_solution(self, substs.0);
+                    self.obligations.push(obligation);
+                }
+                Some(_) => {
+                    // FIXME use this when trying to resolve everything at the end
+                    self.obligations.push(obligation);
+                }
+                None => {
+                    // FIXME obligation cannot be fulfilled => diagnostic
+                }
+            };
+        }
+    }
+
+    /// Resolves the type as far as currently possible, replacing type variables
+    /// by their known types. All types returned by the infer_* functions should
+    /// be resolved as far as possible, i.e. contain no type variables with
+    /// known type.
+    fn resolve_ty_as_possible(&mut self, tv_stack: &mut Vec<TypeVarId>, ty: Ty) -> Ty {
+        self.resolve_obligations_as_possible();
+
+        ty.fold(&mut |ty| match ty {
+            Ty::Infer(tv) => {
+                let inner = tv.to_inner();
+                if tv_stack.contains(&inner) {
+                    tested_by!(type_var_cycles_resolve_as_possible);
+                    // recursive type
+                    return tv.fallback_value();
+                }
+                if let Some(known_ty) =
+                    self.var_unification_table.inlined_probe_value(inner).known()
+                {
+                    // known_ty may contain other variables that are known by now
+                    tv_stack.push(inner);
+                    let result = self.resolve_ty_as_possible(tv_stack, known_ty.clone());
+                    tv_stack.pop();
+                    result
+                } else {
+                    ty
+                }
+            }
+            _ => ty,
+        })
+    }
+
+    /// If `ty` is a type variable with known type, returns that type;
+    /// otherwise, return ty.
+    fn resolve_ty_shallow<'b>(&mut self, ty: &'b Ty) -> Cow<'b, Ty> {
+        let mut ty = Cow::Borrowed(ty);
+        // The type variable could resolve to a int/float variable. Hence try
+        // resolving up to three times; each type of variable shouldn't occur
+        // more than once
+        for i in 0..3 {
+            if i > 0 {
+                tested_by!(type_var_resolves_to_int_var);
+            }
+            match &*ty {
+                Ty::Infer(tv) => {
+                    let inner = tv.to_inner();
+                    match self.var_unification_table.inlined_probe_value(inner).known() {
+                        Some(known_ty) => {
+                            // The known_ty can't be a type var itself
+                            ty = Cow::Owned(known_ty.clone());
+                        }
+                        _ => return ty,
+                    }
+                }
+                _ => return ty,
+            }
+        }
+        log::error!("Inference variable still not resolved: {:?}", ty);
+        ty
+    }
+
+    /// Recurses through the given type, normalizing associated types mentioned
+    /// in it by replacing them by type variables and registering obligations to
+    /// resolve later. This should be done once for every type we get from some
+    /// type annotation (e.g. from a let type annotation, field type or function
+    /// call). `make_ty` handles this already, but e.g. for field types we need
+    /// to do it as well.
+    fn normalize_associated_types_in(&mut self, ty: Ty) -> Ty {
+        let ty = self.resolve_ty_as_possible(&mut vec![], ty);
+        ty.fold(&mut |ty| match ty {
+            Ty::Projection(proj_ty) => self.normalize_projection_ty(proj_ty),
+            _ => ty,
+        })
+    }
+
+    fn normalize_projection_ty(&mut self, proj_ty: ProjectionTy) -> Ty {
+        let var = self.new_type_var();
+        let predicate = ProjectionPredicate { projection_ty: proj_ty, ty: var.clone() };
+        let obligation = Obligation::Projection(predicate);
+        self.obligations.push(obligation);
+        var
+    }
+
+    /// Resolves the type completely; type variables without known type are
+    /// replaced by Ty::Unknown.
+    fn resolve_ty_completely(&mut self, tv_stack: &mut Vec<TypeVarId>, ty: Ty) -> Ty {
+        ty.fold(&mut |ty| match ty {
+            Ty::Infer(tv) => {
+                let inner = tv.to_inner();
+                if tv_stack.contains(&inner) {
+                    tested_by!(type_var_cycles_resolve_completely);
+                    // recursive type
+                    return tv.fallback_value();
+                }
+                if let Some(known_ty) =
+                    self.var_unification_table.inlined_probe_value(inner).known()
+                {
+                    // known_ty may contain other variables that are known by now
+                    tv_stack.push(inner);
+                    let result = self.resolve_ty_completely(tv_stack, known_ty.clone());
+                    tv_stack.pop();
+                    result
+                } else {
+                    tv.fallback_value()
+                }
+            }
+            _ => ty,
+        })
+    }
+
+    fn resolve_variant(&mut self, path: Option<&Path>) -> (Ty, Option<VariantId>) {
+        let path = match path {
+            Some(path) => path,
+            None => return (Ty::Unknown, None),
+        };
+        let resolver = &self.resolver;
+        // FIXME: this should resolve assoc items as well, see this example:
+        // https://play.rust-lang.org/?gist=087992e9e22495446c01c0d4e2d69521
+        match resolver.resolve_path_in_type_ns_fully(self.db, &path) {
+            Some(TypeNs::AdtId(AdtId::StructId(strukt))) => {
+                let substs = Ty::substs_from_path(self.db, resolver, path, strukt.into());
+                let ty = self.db.ty(strukt.into());
+                let ty = self.insert_type_vars(ty.apply_substs(substs));
+                (ty, Some(strukt.into()))
+            }
+            Some(TypeNs::EnumVariantId(var)) => {
+                let substs = Ty::substs_from_path(self.db, resolver, path, var.into());
+                let ty = self.db.ty(var.parent.into());
+                let ty = self.insert_type_vars(ty.apply_substs(substs));
+                (ty, Some(var.into()))
+            }
+            Some(_) | None => (Ty::Unknown, None),
+        }
+    }
+
+    fn collect_const(&mut self, data: &ConstData) {
+        self.return_ty = self.make_ty(&data.type_ref);
+    }
+
+    fn collect_fn(&mut self, data: &FunctionData) {
+        let body = Arc::clone(&self.body); // avoid borrow checker problem
+        for (type_ref, pat) in data.params.iter().zip(body.params.iter()) {
+            let ty = self.make_ty(type_ref);
+
+            self.infer_pat(*pat, &ty, BindingMode::default());
+        }
+        self.return_ty = self.make_ty(&data.ret_type);
+    }
+
+    fn infer_body(&mut self) {
+        self.infer_expr(self.body.body_expr, &Expectation::has_type(self.return_ty.clone()));
+    }
+
+    fn resolve_into_iter_item(&self) -> Option<TypeAliasId> {
+        let path = known::std_iter_into_iterator();
+        let trait_ = self.resolver.resolve_known_trait(self.db, &path)?;
+        self.db.trait_data(trait_).associated_type_by_name(&name::ITEM_TYPE)
+    }
+
+    fn resolve_ops_try_ok(&self) -> Option<TypeAliasId> {
+        let path = known::std_ops_try();
+        let trait_ = self.resolver.resolve_known_trait(self.db, &path)?;
+        self.db.trait_data(trait_).associated_type_by_name(&name::OK_TYPE)
+    }
+
+    fn resolve_future_future_output(&self) -> Option<TypeAliasId> {
+        let path = known::std_future_future();
+        let trait_ = self.resolver.resolve_known_trait(self.db, &path)?;
+        self.db.trait_data(trait_).associated_type_by_name(&name::OUTPUT_TYPE)
+    }
+
+    fn resolve_boxed_box(&self) -> Option<AdtId> {
+        let path = known::std_boxed_box();
+        let struct_ = self.resolver.resolve_known_struct(self.db, &path)?;
+        Some(struct_.into())
+    }
+}
+
+/// The ID of a type variable.
+#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
+pub struct TypeVarId(pub(super) u32);
+
+impl UnifyKey for TypeVarId {
+    type Value = TypeVarValue;
+
+    fn index(&self) -> u32 {
+        self.0
+    }
+
+    fn from_index(i: u32) -> Self {
+        TypeVarId(i)
+    }
+
+    fn tag() -> &'static str {
+        "TypeVarId"
+    }
+}
+
+/// The value of a type variable: either we already know the type, or we don't
+/// know it yet.
+#[derive(Clone, PartialEq, Eq, Debug)]
+pub enum TypeVarValue {
+    Known(Ty),
+    Unknown,
+}
+
+impl TypeVarValue {
+    fn known(&self) -> Option<&Ty> {
+        match self {
+            TypeVarValue::Known(ty) => Some(ty),
+            TypeVarValue::Unknown => None,
+        }
+    }
+}
+
+impl UnifyValue for TypeVarValue {
+    type Error = NoError;
+
+    fn unify_values(value1: &Self, value2: &Self) -> Result<Self, NoError> {
+        match (value1, value2) {
+            // We should never equate two type variables, both of which have
+            // known types. Instead, we recursively equate those types.
+            (TypeVarValue::Known(t1), TypeVarValue::Known(t2)) => panic!(
+                "equating two type variables, both of which have known types: {:?} and {:?}",
+                t1, t2
+            ),
+
+            // If one side is known, prefer that one.
+            (TypeVarValue::Known(..), TypeVarValue::Unknown) => Ok(value1.clone()),
+            (TypeVarValue::Unknown, TypeVarValue::Known(..)) => Ok(value2.clone()),
+
+            (TypeVarValue::Unknown, TypeVarValue::Unknown) => Ok(TypeVarValue::Unknown),
+        }
+    }
+}
+
+/// The kinds of placeholders we need during type inference. There's separate
+/// values for general types, and for integer and float variables. The latter
+/// two are used for inference of literal values (e.g. `100` could be one of
+/// several integer types).
+#[derive(Clone, Copy, PartialEq, Eq, Hash, Debug)]
+pub enum InferTy {
+    TypeVar(TypeVarId),
+    IntVar(TypeVarId),
+    FloatVar(TypeVarId),
+    MaybeNeverTypeVar(TypeVarId),
+}
+
+impl InferTy {
+    fn to_inner(self) -> TypeVarId {
+        match self {
+            InferTy::TypeVar(ty)
+            | InferTy::IntVar(ty)
+            | InferTy::FloatVar(ty)
+            | InferTy::MaybeNeverTypeVar(ty) => ty,
+        }
+    }
+
+    fn fallback_value(self) -> Ty {
+        match self {
+            InferTy::TypeVar(..) => Ty::Unknown,
+            InferTy::IntVar(..) => Ty::simple(TypeCtor::Int(Uncertain::Known(IntTy::i32()))),
+            InferTy::FloatVar(..) => Ty::simple(TypeCtor::Float(Uncertain::Known(FloatTy::f64()))),
+            InferTy::MaybeNeverTypeVar(..) => Ty::simple(TypeCtor::Never),
+        }
+    }
+}
+
+/// When inferring an expression, we propagate downward whatever type hint we
+/// are able in the form of an `Expectation`.
+#[derive(Clone, PartialEq, Eq, Debug)]
+struct Expectation {
+    ty: Ty,
+    // FIXME: In some cases, we need to be aware whether the expectation is that
+    // the type match exactly what we passed, or whether it just needs to be
+    // coercible to the expected type. See Expectation::rvalue_hint in rustc.
+}
+
+impl Expectation {
+    /// The expectation that the type of the expression needs to equal the given
+    /// type.
+    fn has_type(ty: Ty) -> Self {
+        Expectation { ty }
+    }
+
+    /// This expresses no expectation on the type.
+    fn none() -> Self {
+        Expectation { ty: Ty::Unknown }
+    }
+}
+
+mod diagnostics {
+    use hir_def::{expr::ExprId, FunctionId, HasSource, Lookup};
+    use hir_expand::diagnostics::DiagnosticSink;
+
+    use crate::{db::HirDatabase, diagnostics::NoSuchField};
+
+    #[derive(Debug, PartialEq, Eq, Clone)]
+    pub(super) enum InferenceDiagnostic {
+        NoSuchField { expr: ExprId, field: usize },
+    }
+
+    impl InferenceDiagnostic {
+        pub(super) fn add_to(
+            &self,
+            db: &impl HirDatabase,
+            owner: FunctionId,
+            sink: &mut DiagnosticSink,
+        ) {
+            match self {
+                InferenceDiagnostic::NoSuchField { expr, field } => {
+                    let file = owner.lookup(db).source(db).file_id;
+                    let (_, source_map) = db.body_with_source_map(owner.into());
+                    let field = source_map.field_syntax(*expr, *field);
+                    sink.push(NoSuchField { file, field })
+                }
+            }
+        }
+    }
+}
diff --git a/crates/ra_hir_ty/src/infer/coerce.rs b/crates/ra_hir_ty/src/infer/coerce.rs
new file mode 100644
index 000000000..719a0f395
--- /dev/null
+++ b/crates/ra_hir_ty/src/infer/coerce.rs
@@ -0,0 +1,344 @@
+//! Coercion logic. Coercions are certain type conversions that can implicitly
+//! happen in certain places, e.g. weakening `&mut` to `&` or deref coercions
+//! like going from `&Vec<T>` to `&[T]`.
+//!
+//! See: https://doc.rust-lang.org/nomicon/coercions.html
+
+use hir_def::{lang_item::LangItemTarget, resolver::Resolver, type_ref::Mutability, AdtId};
+use rustc_hash::FxHashMap;
+use test_utils::tested_by;
+
+use crate::{autoderef, db::HirDatabase, ImplTy, Substs, Ty, TypeCtor, TypeWalk};
+
+use super::{InEnvironment, InferTy, InferenceContext, TypeVarValue};
+
+impl<'a, D: HirDatabase> InferenceContext<'a, D> {
+    /// Unify two types, but may coerce the first one to the second one
+    /// using "implicit coercion rules" if needed.
+    pub(super) fn coerce(&mut self, from_ty: &Ty, to_ty: &Ty) -> bool {
+        let from_ty = self.resolve_ty_shallow(from_ty).into_owned();
+        let to_ty = self.resolve_ty_shallow(to_ty);
+        self.coerce_inner(from_ty, &to_ty)
+    }
+
+    /// Merge two types from different branches, with possible implicit coerce.
+    ///
+    /// Note that it is only possible that one type are coerced to another.
+    /// Coercing both types to another least upper bound type is not possible in rustc,
+    /// which will simply result in "incompatible types" error.
+    pub(super) fn coerce_merge_branch<'t>(&mut self, ty1: &Ty, ty2: &Ty) -> Ty {
+        if self.coerce(ty1, ty2) {
+            ty2.clone()
+        } else if self.coerce(ty2, ty1) {
+            ty1.clone()
+        } else {
+            tested_by!(coerce_merge_fail_fallback);
+            // For incompatible types, we use the latter one as result
+            // to be better recovery for `if` without `else`.
+            ty2.clone()
+        }
+    }
+
+    pub(super) fn init_coerce_unsized_map(
+        db: &'a D,
+        resolver: &Resolver,
+    ) -> FxHashMap<(TypeCtor, TypeCtor), usize> {
+        let krate = resolver.krate().unwrap();
+        let impls = match db.lang_item(krate.into(), "coerce_unsized".into()) {
+            Some(LangItemTarget::TraitId(trait_)) => {
+                db.impls_for_trait(krate.into(), trait_.into())
+            }
+            _ => return FxHashMap::default(),
+        };
+
+        impls
+            .iter()
+            .filter_map(|&impl_id| {
+                let trait_ref = match db.impl_ty(impl_id) {
+                    ImplTy::TraitRef(it) => it,
+                    ImplTy::Inherent(_) => return None,
+                };
+
+                // `CoerseUnsized` has one generic parameter for the target type.
+                let cur_from_ty = trait_ref.substs.0.get(0)?;
+                let cur_to_ty = trait_ref.substs.0.get(1)?;
+
+                match (&cur_from_ty, cur_to_ty) {
+                    (ty_app!(ctor1, st1), ty_app!(ctor2, st2)) => {
+                        // FIXME: We return the first non-equal bound as the type parameter to coerce to unsized type.
+                        // This works for smart-pointer-like coercion, which covers all impls from std.
+                        st1.iter().zip(st2.iter()).enumerate().find_map(|(i, (ty1, ty2))| {
+                            match (ty1, ty2) {
+                                (Ty::Param { idx: p1, .. }, Ty::Param { idx: p2, .. })
+                                    if p1 != p2 =>
+                                {
+                                    Some(((*ctor1, *ctor2), i))
+                                }
+                                _ => None,
+                            }
+                        })
+                    }
+                    _ => None,
+                }
+            })
+            .collect()
+    }
+
+    fn coerce_inner(&mut self, mut from_ty: Ty, to_ty: &Ty) -> bool {
+        match (&from_ty, to_ty) {
+            // Never type will make type variable to fallback to Never Type instead of Unknown.
+            (ty_app!(TypeCtor::Never), Ty::Infer(InferTy::TypeVar(tv))) => {
+                let var = self.new_maybe_never_type_var();
+                self.var_unification_table.union_value(*tv, TypeVarValue::Known(var));
+                return true;
+            }
+            (ty_app!(TypeCtor::Never), _) => return true,
+
+            // Trivial cases, this should go after `never` check to
+            // avoid infer result type to be never
+            _ => {
+                if self.unify_inner_trivial(&from_ty, &to_ty) {
+                    return true;
+                }
+            }
+        }
+
+        // Pointer weakening and function to pointer
+        match (&mut from_ty, to_ty) {
+            // `*mut T`, `&mut T, `&T`` -> `*const T`
+            // `&mut T` -> `&T`
+            // `&mut T` -> `*mut T`
+            (ty_app!(c1@TypeCtor::RawPtr(_)), ty_app!(c2@TypeCtor::RawPtr(Mutability::Shared)))
+            | (ty_app!(c1@TypeCtor::Ref(_)), ty_app!(c2@TypeCtor::RawPtr(Mutability::Shared)))
+            | (ty_app!(c1@TypeCtor::Ref(_)), ty_app!(c2@TypeCtor::Ref(Mutability::Shared)))
+            | (ty_app!(c1@TypeCtor::Ref(Mutability::Mut)), ty_app!(c2@TypeCtor::RawPtr(_))) => {
+                *c1 = *c2;
+            }
+
+            // Illegal mutablity conversion
+            (
+                ty_app!(TypeCtor::RawPtr(Mutability::Shared)),
+                ty_app!(TypeCtor::RawPtr(Mutability::Mut)),
+            )
+            | (
+                ty_app!(TypeCtor::Ref(Mutability::Shared)),
+                ty_app!(TypeCtor::Ref(Mutability::Mut)),
+            ) => return false,
+
+            // `{function_type}` -> `fn()`
+            (ty_app!(TypeCtor::FnDef(_)), ty_app!(TypeCtor::FnPtr { .. })) => {
+                match from_ty.callable_sig(self.db) {
+                    None => return false,
+                    Some(sig) => {
+                        let num_args = sig.params_and_return.len() as u16 - 1;
+                        from_ty =
+                            Ty::apply(TypeCtor::FnPtr { num_args }, Substs(sig.params_and_return));
+                    }
+                }
+            }
+
+            _ => {}
+        }
+
+        if let Some(ret) = self.try_coerce_unsized(&from_ty, &to_ty) {
+            return ret;
+        }
+
+        // Auto Deref if cannot coerce
+        match (&from_ty, to_ty) {
+            // FIXME: DerefMut
+            (ty_app!(TypeCtor::Ref(_), st1), ty_app!(TypeCtor::Ref(_), st2)) => {
+                self.unify_autoderef_behind_ref(&st1[0], &st2[0])
+            }
+
+            // Otherwise, normal unify
+            _ => self.unify(&from_ty, to_ty),
+        }
+    }
+
+    /// Coerce a type using `from_ty: CoerceUnsized<ty_ty>`
+    ///
+    /// See: https://doc.rust-lang.org/nightly/std/marker/trait.CoerceUnsized.html
+    fn try_coerce_unsized(&mut self, from_ty: &Ty, to_ty: &Ty) -> Option<bool> {
+        let (ctor1, st1, ctor2, st2) = match (from_ty, to_ty) {
+            (ty_app!(ctor1, st1), ty_app!(ctor2, st2)) => (ctor1, st1, ctor2, st2),
+            _ => return None,
+        };
+
+        let coerce_generic_index = *self.coerce_unsized_map.get(&(*ctor1, *ctor2))?;
+
+        // Check `Unsize` first
+        match self.check_unsize_and_coerce(
+            st1.0.get(coerce_generic_index)?,
+            st2.0.get(coerce_generic_index)?,
+            0,
+        ) {
+            Some(true) => {}
+            ret => return ret,
+        }
+
+        let ret = st1
+            .iter()
+            .zip(st2.iter())
+            .enumerate()
+            .filter(|&(idx, _)| idx != coerce_generic_index)
+            .all(|(_, (ty1, ty2))| self.unify(ty1, ty2));
+
+        Some(ret)
+    }
+
+    /// Check if `from_ty: Unsize<to_ty>`, and coerce to `to_ty` if it holds.
+    ///
+    /// It should not be directly called. It is only used by `try_coerce_unsized`.
+    ///
+    /// See: https://doc.rust-lang.org/nightly/std/marker/trait.Unsize.html
+    fn check_unsize_and_coerce(&mut self, from_ty: &Ty, to_ty: &Ty, depth: usize) -> Option<bool> {
+        if depth > 1000 {
+            panic!("Infinite recursion in coercion");
+        }
+
+        match (&from_ty, &to_ty) {
+            // `[T; N]` -> `[T]`
+            (ty_app!(TypeCtor::Array, st1), ty_app!(TypeCtor::Slice, st2)) => {
+                Some(self.unify(&st1[0], &st2[0]))
+            }
+
+            // `T` -> `dyn Trait` when `T: Trait`
+            (_, Ty::Dyn(_)) => {
+                // FIXME: Check predicates
+                Some(true)
+            }
+
+            // `(..., T)` -> `(..., U)` when `T: Unsize<U>`
+            (
+                ty_app!(TypeCtor::Tuple { cardinality: len1 }, st1),
+                ty_app!(TypeCtor::Tuple { cardinality: len2 }, st2),
+            ) => {
+                if len1 != len2 || *len1 == 0 {
+                    return None;
+                }
+
+                match self.check_unsize_and_coerce(
+                    st1.last().unwrap(),
+                    st2.last().unwrap(),
+                    depth + 1,
+                ) {
+                    Some(true) => {}
+                    ret => return ret,
+                }
+
+                let ret = st1[..st1.len() - 1]
+                    .iter()
+                    .zip(&st2[..st2.len() - 1])
+                    .all(|(ty1, ty2)| self.unify(ty1, ty2));
+
+                Some(ret)
+            }
+
+            // Foo<..., T, ...> is Unsize<Foo<..., U, ...>> if:
+            // - T: Unsize<U>
+            // - Foo is a struct
+            // - Only the last field of Foo has a type involving T
+            // - T is not part of the type of any other fields
+            // - Bar<T>: Unsize<Bar<U>>, if the last field of Foo has type Bar<T>
+            (
+                ty_app!(TypeCtor::Adt(AdtId::StructId(struct1)), st1),
+                ty_app!(TypeCtor::Adt(AdtId::StructId(struct2)), st2),
+            ) if struct1 == struct2 => {
+                let field_tys = self.db.field_types((*struct1).into());
+                let struct_data = self.db.struct_data(*struct1);
+
+                let mut fields = struct_data.variant_data.fields().iter();
+                let (last_field_id, _data) = fields.next_back()?;
+
+                // Get the generic parameter involved in the last field.
+                let unsize_generic_index = {
+                    let mut index = None;
+                    let mut multiple_param = false;
+                    field_tys[last_field_id].walk(&mut |ty| match ty {
+                        &Ty::Param { idx, .. } => {
+                            if index.is_none() {
+                                index = Some(idx);
+                            } else if Some(idx) != index {
+                                multiple_param = true;
+                            }
+                        }
+                        _ => {}
+                    });
+
+                    if multiple_param {
+                        return None;
+                    }
+                    index?
+                };
+
+                // Check other fields do not involve it.
+                let mut multiple_used = false;
+                fields.for_each(|(field_id, _data)| {
+                    field_tys[field_id].walk(&mut |ty| match ty {
+                        &Ty::Param { idx, .. } if idx == unsize_generic_index => {
+                            multiple_used = true
+                        }
+                        _ => {}
+                    })
+                });
+                if multiple_used {
+                    return None;
+                }
+
+                let unsize_generic_index = unsize_generic_index as usize;
+
+                // Check `Unsize` first
+                match self.check_unsize_and_coerce(
+                    st1.get(unsize_generic_index)?,
+                    st2.get(unsize_generic_index)?,
+                    depth + 1,
+                ) {
+                    Some(true) => {}
+                    ret => return ret,
+                }
+
+                // Then unify other parameters
+                let ret = st1
+                    .iter()
+                    .zip(st2.iter())
+                    .enumerate()
+                    .filter(|&(idx, _)| idx != unsize_generic_index)
+                    .all(|(_, (ty1, ty2))| self.unify(ty1, ty2));
+
+                Some(ret)
+            }
+
+            _ => None,
+        }
+    }
+
+    /// Unify `from_ty` to `to_ty` with optional auto Deref
+    ///
+    /// Note that the parameters are already stripped the outer reference.
+    fn unify_autoderef_behind_ref(&mut self, from_ty: &Ty, to_ty: &Ty) -> bool {
+        let canonicalized = self.canonicalizer().canonicalize_ty(from_ty.clone());
+        let to_ty = self.resolve_ty_shallow(&to_ty);
+        // FIXME: Auto DerefMut
+        for derefed_ty in autoderef::autoderef(
+            self.db,
+            self.resolver.krate(),
+            InEnvironment {
+                value: canonicalized.value.clone(),
+                environment: self.trait_env.clone(),
+            },
+        ) {
+            let derefed_ty = canonicalized.decanonicalize_ty(derefed_ty.value);
+            match (&*self.resolve_ty_shallow(&derefed_ty), &*to_ty) {
+                // Stop when constructor matches.
+                (ty_app!(from_ctor, st1), ty_app!(to_ctor, st2)) if from_ctor == to_ctor => {
+                    // It will not recurse to `coerce`.
+                    return self.unify_substs(st1, st2, 0);
+                }
+                _ => {}
+            }
+        }
+
+        false
+    }
+}
diff --git a/crates/ra_hir_ty/src/infer/expr.rs b/crates/ra_hir_ty/src/infer/expr.rs
new file mode 100644
index 000000000..2f9ca4bbb
--- /dev/null
+++ b/crates/ra_hir_ty/src/infer/expr.rs
@@ -0,0 +1,686 @@
+//! Type inference for expressions.
+
+use std::iter::{repeat, repeat_with};
+use std::sync::Arc;
+
+use hir_def::{
+    builtin_type::Signedness,
+    expr::{Array, BinaryOp, Expr, ExprId, Literal, Statement, UnaryOp},
+    generics::GenericParams,
+    path::{GenericArg, GenericArgs},
+    resolver::resolver_for_expr,
+    AdtId, ContainerId, Lookup, StructFieldId,
+};
+use hir_expand::name::{self, Name};
+
+use crate::{
+    autoderef, db::HirDatabase, method_resolution, op, traits::InEnvironment, utils::variant_data,
+    CallableDef, InferTy, IntTy, Mutability, Obligation, ProjectionPredicate, ProjectionTy, Substs,
+    TraitRef, Ty, TypeCtor, TypeWalk, Uncertain,
+};
+
+use super::{BindingMode, Expectation, InferenceContext, InferenceDiagnostic, TypeMismatch};
+
+impl<'a, D: HirDatabase> InferenceContext<'a, D> {
+    pub(super) fn infer_expr(&mut self, tgt_expr: ExprId, expected: &Expectation) -> Ty {
+        let ty = self.infer_expr_inner(tgt_expr, expected);
+        let could_unify = self.unify(&ty, &expected.ty);
+        if !could_unify {
+            self.result.type_mismatches.insert(
+                tgt_expr,
+                TypeMismatch { expected: expected.ty.clone(), actual: ty.clone() },
+            );
+        }
+        let ty = self.resolve_ty_as_possible(&mut vec![], ty);
+        ty
+    }
+
+    /// Infer type of expression with possibly implicit coerce to the expected type.
+    /// Return the type after possible coercion.
+    fn infer_expr_coerce(&mut self, expr: ExprId, expected: &Expectation) -> Ty {
+        let ty = self.infer_expr_inner(expr, &expected);
+        let ty = if !self.coerce(&ty, &expected.ty) {
+            self.result
+                .type_mismatches
+                .insert(expr, TypeMismatch { expected: expected.ty.clone(), actual: ty.clone() });
+            // Return actual type when type mismatch.
+            // This is needed for diagnostic when return type mismatch.
+            ty
+        } else if expected.ty == Ty::Unknown {
+            ty
+        } else {
+            expected.ty.clone()
+        };
+
+        self.resolve_ty_as_possible(&mut vec![], ty)
+    }
+
+    fn infer_expr_inner(&mut self, tgt_expr: ExprId, expected: &Expectation) -> Ty {
+        let body = Arc::clone(&self.body); // avoid borrow checker problem
+        let ty = match &body[tgt_expr] {
+            Expr::Missing => Ty::Unknown,
+            Expr::If { condition, then_branch, else_branch } => {
+                // if let is desugared to match, so this is always simple if
+                self.infer_expr(*condition, &Expectation::has_type(Ty::simple(TypeCtor::Bool)));
+
+                let then_ty = self.infer_expr_inner(*then_branch, &expected);
+                let else_ty = match else_branch {
+                    Some(else_branch) => self.infer_expr_inner(*else_branch, &expected),
+                    None => Ty::unit(),
+                };
+
+                self.coerce_merge_branch(&then_ty, &else_ty)
+            }
+            Expr::Block { statements, tail } => self.infer_block(statements, *tail, expected),
+            Expr::TryBlock { body } => {
+                let _inner = self.infer_expr(*body, expected);
+                // FIXME should be std::result::Result<{inner}, _>
+                Ty::Unknown
+            }
+            Expr::Loop { body } => {
+                self.infer_expr(*body, &Expectation::has_type(Ty::unit()));
+                // FIXME handle break with value
+                Ty::simple(TypeCtor::Never)
+            }
+            Expr::While { condition, body } => {
+                // while let is desugared to a match loop, so this is always simple while
+                self.infer_expr(*condition, &Expectation::has_type(Ty::simple(TypeCtor::Bool)));
+                self.infer_expr(*body, &Expectation::has_type(Ty::unit()));
+                Ty::unit()
+            }
+            Expr::For { iterable, body, pat } => {
+                let iterable_ty = self.infer_expr(*iterable, &Expectation::none());
+
+                let pat_ty = match self.resolve_into_iter_item() {
+                    Some(into_iter_item_alias) => {
+                        let pat_ty = self.new_type_var();
+                        let projection = ProjectionPredicate {
+                            ty: pat_ty.clone(),
+                            projection_ty: ProjectionTy {
+                                associated_ty: into_iter_item_alias,
+                                parameters: Substs::single(iterable_ty),
+                            },
+                        };
+                        self.obligations.push(Obligation::Projection(projection));
+                        self.resolve_ty_as_possible(&mut vec![], pat_ty)
+                    }
+                    None => Ty::Unknown,
+                };
+
+                self.infer_pat(*pat, &pat_ty, BindingMode::default());
+                self.infer_expr(*body, &Expectation::has_type(Ty::unit()));
+                Ty::unit()
+            }
+            Expr::Lambda { body, args, arg_types } => {
+                assert_eq!(args.len(), arg_types.len());
+
+                let mut sig_tys = Vec::new();
+
+                for (arg_pat, arg_type) in args.iter().zip(arg_types.iter()) {
+                    let expected = if let Some(type_ref) = arg_type {
+                        self.make_ty(type_ref)
+                    } else {
+                        Ty::Unknown
+                    };
+                    let arg_ty = self.infer_pat(*arg_pat, &expected, BindingMode::default());
+                    sig_tys.push(arg_ty);
+                }
+
+                // add return type
+                let ret_ty = self.new_type_var();
+                sig_tys.push(ret_ty.clone());
+                let sig_ty = Ty::apply(
+                    TypeCtor::FnPtr { num_args: sig_tys.len() as u16 - 1 },
+                    Substs(sig_tys.into()),
+                );
+                let closure_ty = Ty::apply_one(
+                    TypeCtor::Closure { def: self.owner.into(), expr: tgt_expr },
+                    sig_ty,
+                );
+
+                // Eagerly try to relate the closure type with the expected
+                // type, otherwise we often won't have enough information to
+                // infer the body.
+                self.coerce(&closure_ty, &expected.ty);
+
+                self.infer_expr(*body, &Expectation::has_type(ret_ty));
+                closure_ty
+            }
+            Expr::Call { callee, args } => {
+                let callee_ty = self.infer_expr(*callee, &Expectation::none());
+                let (param_tys, ret_ty) = match callee_ty.callable_sig(self.db) {
+                    Some(sig) => (sig.params().to_vec(), sig.ret().clone()),
+                    None => {
+                        // Not callable
+                        // FIXME: report an error
+                        (Vec::new(), Ty::Unknown)
+                    }
+                };
+                self.register_obligations_for_call(&callee_ty);
+                self.check_call_arguments(args, &param_tys);
+                let ret_ty = self.normalize_associated_types_in(ret_ty);
+                ret_ty
+            }
+            Expr::MethodCall { receiver, args, method_name, generic_args } => self
+                .infer_method_call(tgt_expr, *receiver, &args, &method_name, generic_args.as_ref()),
+            Expr::Match { expr, arms } => {
+                let input_ty = self.infer_expr(*expr, &Expectation::none());
+
+                let mut result_ty = self.new_maybe_never_type_var();
+
+                for arm in arms {
+                    for &pat in &arm.pats {
+                        let _pat_ty = self.infer_pat(pat, &input_ty, BindingMode::default());
+                    }
+                    if let Some(guard_expr) = arm.guard {
+                        self.infer_expr(
+                            guard_expr,
+                            &Expectation::has_type(Ty::simple(TypeCtor::Bool)),
+                        );
+                    }
+
+                    let arm_ty = self.infer_expr_inner(arm.expr, &expected);
+                    result_ty = self.coerce_merge_branch(&result_ty, &arm_ty);
+                }
+
+                result_ty
+            }
+            Expr::Path(p) => {
+                // FIXME this could be more efficient...
+                let resolver = resolver_for_expr(self.db, self.owner.into(), tgt_expr);
+                self.infer_path(&resolver, p, tgt_expr.into()).unwrap_or(Ty::Unknown)
+            }
+            Expr::Continue => Ty::simple(TypeCtor::Never),
+            Expr::Break { expr } => {
+                if let Some(expr) = expr {
+                    // FIXME handle break with value
+                    self.infer_expr(*expr, &Expectation::none());
+                }
+                Ty::simple(TypeCtor::Never)
+            }
+            Expr::Return { expr } => {
+                if let Some(expr) = expr {
+                    self.infer_expr(*expr, &Expectation::has_type(self.return_ty.clone()));
+                }
+                Ty::simple(TypeCtor::Never)
+            }
+            Expr::RecordLit { path, fields, spread } => {
+                let (ty, def_id) = self.resolve_variant(path.as_ref());
+                if let Some(variant) = def_id {
+                    self.write_variant_resolution(tgt_expr.into(), variant);
+                }
+
+                self.unify(&ty, &expected.ty);
+
+                let substs = ty.substs().unwrap_or_else(Substs::empty);
+                let field_types =
+                    def_id.map(|it| self.db.field_types(it.into())).unwrap_or_default();
+                let variant_data = def_id.map(|it| variant_data(self.db, it));
+                for (field_idx, field) in fields.iter().enumerate() {
+                    let field_def =
+                        variant_data.as_ref().and_then(|it| match it.field(&field.name) {
+                            Some(local_id) => {
+                                Some(StructFieldId { parent: def_id.unwrap(), local_id })
+                            }
+                            None => {
+                                self.push_diagnostic(InferenceDiagnostic::NoSuchField {
+                                    expr: tgt_expr,
+                                    field: field_idx,
+                                });
+                                None
+                            }
+                        });
+                    if let Some(field_def) = field_def {
+                        self.result.record_field_resolutions.insert(field.expr, field_def);
+                    }
+                    let field_ty = field_def
+                        .map_or(Ty::Unknown, |it| field_types[it.local_id].clone())
+                        .subst(&substs);
+                    self.infer_expr_coerce(field.expr, &Expectation::has_type(field_ty));
+                }
+                if let Some(expr) = spread {
+                    self.infer_expr(*expr, &Expectation::has_type(ty.clone()));
+                }
+                ty
+            }
+            Expr::Field { expr, name } => {
+                let receiver_ty = self.infer_expr(*expr, &Expectation::none());
+                let canonicalized = self.canonicalizer().canonicalize_ty(receiver_ty);
+                let ty = autoderef::autoderef(
+                    self.db,
+                    self.resolver.krate(),
+                    InEnvironment {
+                        value: canonicalized.value.clone(),
+                        environment: self.trait_env.clone(),
+                    },
+                )
+                .find_map(|derefed_ty| match canonicalized.decanonicalize_ty(derefed_ty.value) {
+                    Ty::Apply(a_ty) => match a_ty.ctor {
+                        TypeCtor::Tuple { .. } => name
+                            .as_tuple_index()
+                            .and_then(|idx| a_ty.parameters.0.get(idx).cloned()),
+                        TypeCtor::Adt(AdtId::StructId(s)) => {
+                            self.db.struct_data(s).variant_data.field(name).map(|local_id| {
+                                let field = StructFieldId { parent: s.into(), local_id }.into();
+                                self.write_field_resolution(tgt_expr, field);
+                                self.db.field_types(s.into())[field.local_id]
+                                    .clone()
+                                    .subst(&a_ty.parameters)
+                            })
+                        }
+                        // FIXME:
+                        TypeCtor::Adt(AdtId::UnionId(_)) => None,
+                        _ => None,
+                    },
+                    _ => None,
+                })
+                .unwrap_or(Ty::Unknown);
+                let ty = self.insert_type_vars(ty);
+                self.normalize_associated_types_in(ty)
+            }
+            Expr::Await { expr } => {
+                let inner_ty = self.infer_expr(*expr, &Expectation::none());
+                let ty = match self.resolve_future_future_output() {
+                    Some(future_future_output_alias) => {
+                        let ty = self.new_type_var();
+                        let projection = ProjectionPredicate {
+                            ty: ty.clone(),
+                            projection_ty: ProjectionTy {
+                                associated_ty: future_future_output_alias,
+                                parameters: Substs::single(inner_ty),
+                            },
+                        };
+                        self.obligations.push(Obligation::Projection(projection));
+                        self.resolve_ty_as_possible(&mut vec![], ty)
+                    }
+                    None => Ty::Unknown,
+                };
+                ty
+            }
+            Expr::Try { expr } => {
+                let inner_ty = self.infer_expr(*expr, &Expectation::none());
+                let ty = match self.resolve_ops_try_ok() {
+                    Some(ops_try_ok_alias) => {
+                        let ty = self.new_type_var();
+                        let projection = ProjectionPredicate {
+                            ty: ty.clone(),
+                            projection_ty: ProjectionTy {
+                                associated_ty: ops_try_ok_alias,
+                                parameters: Substs::single(inner_ty),
+                            },
+                        };
+                        self.obligations.push(Obligation::Projection(projection));
+                        self.resolve_ty_as_possible(&mut vec![], ty)
+                    }
+                    None => Ty::Unknown,
+                };
+                ty
+            }
+            Expr::Cast { expr, type_ref } => {
+                let _inner_ty = self.infer_expr(*expr, &Expectation::none());
+                let cast_ty = self.make_ty(type_ref);
+                // FIXME check the cast...
+                cast_ty
+            }
+            Expr::Ref { expr, mutability } => {
+                let expectation =
+                    if let Some((exp_inner, exp_mutability)) = &expected.ty.as_reference() {
+                        if *exp_mutability == Mutability::Mut && *mutability == Mutability::Shared {
+                            // FIXME: throw type error - expected mut reference but found shared ref,
+                            // which cannot be coerced
+                        }
+                        Expectation::has_type(Ty::clone(exp_inner))
+                    } else {
+                        Expectation::none()
+                    };
+                // FIXME reference coercions etc.
+                let inner_ty = self.infer_expr(*expr, &expectation);
+                Ty::apply_one(TypeCtor::Ref(*mutability), inner_ty)
+            }
+            Expr::Box { expr } => {
+                let inner_ty = self.infer_expr(*expr, &Expectation::none());
+                if let Some(box_) = self.resolve_boxed_box() {
+                    Ty::apply_one(TypeCtor::Adt(box_), inner_ty)
+                } else {
+                    Ty::Unknown
+                }
+            }
+            Expr::UnaryOp { expr, op } => {
+                let inner_ty = self.infer_expr(*expr, &Expectation::none());
+                match op {
+                    UnaryOp::Deref => match self.resolver.krate() {
+                        Some(krate) => {
+                            let canonicalized = self.canonicalizer().canonicalize_ty(inner_ty);
+                            match autoderef::deref(
+                                self.db,
+                                krate,
+                                InEnvironment {
+                                    value: &canonicalized.value,
+                                    environment: self.trait_env.clone(),
+                                },
+                            ) {
+                                Some(derefed_ty) => {
+                                    canonicalized.decanonicalize_ty(derefed_ty.value)
+                                }
+                                None => Ty::Unknown,
+                            }
+                        }
+                        None => Ty::Unknown,
+                    },
+                    UnaryOp::Neg => {
+                        match &inner_ty {
+                            Ty::Apply(a_ty) => match a_ty.ctor {
+                                TypeCtor::Int(Uncertain::Unknown)
+                                | TypeCtor::Int(Uncertain::Known(IntTy {
+                                    signedness: Signedness::Signed,
+                                    ..
+                                }))
+                                | TypeCtor::Float(..) => inner_ty,
+                                _ => Ty::Unknown,
+                            },
+                            Ty::Infer(InferTy::IntVar(..)) | Ty::Infer(InferTy::FloatVar(..)) => {
+                                inner_ty
+                            }
+                            // FIXME: resolve ops::Neg trait
+                            _ => Ty::Unknown,
+                        }
+                    }
+                    UnaryOp::Not => {
+                        match &inner_ty {
+                            Ty::Apply(a_ty) => match a_ty.ctor {
+                                TypeCtor::Bool | TypeCtor::Int(_) => inner_ty,
+                                _ => Ty::Unknown,
+                            },
+                            Ty::Infer(InferTy::IntVar(..)) => inner_ty,
+                            // FIXME: resolve ops::Not trait for inner_ty
+                            _ => Ty::Unknown,
+                        }
+                    }
+                }
+            }
+            Expr::BinaryOp { lhs, rhs, op } => match op {
+                Some(op) => {
+                    let lhs_expectation = match op {
+                        BinaryOp::LogicOp(..) => Expectation::has_type(Ty::simple(TypeCtor::Bool)),
+                        _ => Expectation::none(),
+                    };
+                    let lhs_ty = self.infer_expr(*lhs, &lhs_expectation);
+                    // FIXME: find implementation of trait corresponding to operation
+                    // symbol and resolve associated `Output` type
+                    let rhs_expectation = op::binary_op_rhs_expectation(*op, lhs_ty);
+                    let rhs_ty = self.infer_expr(*rhs, &Expectation::has_type(rhs_expectation));
+
+                    // FIXME: similar as above, return ty is often associated trait type
+                    op::binary_op_return_ty(*op, rhs_ty)
+                }
+                _ => Ty::Unknown,
+            },
+            Expr::Index { base, index } => {
+                let _base_ty = self.infer_expr(*base, &Expectation::none());
+                let _index_ty = self.infer_expr(*index, &Expectation::none());
+                // FIXME: use `std::ops::Index::Output` to figure out the real return type
+                Ty::Unknown
+            }
+            Expr::Tuple { exprs } => {
+                let mut tys = match &expected.ty {
+                    ty_app!(TypeCtor::Tuple { .. }, st) => st
+                        .iter()
+                        .cloned()
+                        .chain(repeat_with(|| self.new_type_var()))
+                        .take(exprs.len())
+                        .collect::<Vec<_>>(),
+                    _ => (0..exprs.len()).map(|_| self.new_type_var()).collect(),
+                };
+
+                for (expr, ty) in exprs.iter().zip(tys.iter_mut()) {
+                    self.infer_expr_coerce(*expr, &Expectation::has_type(ty.clone()));
+                }
+
+                Ty::apply(TypeCtor::Tuple { cardinality: tys.len() as u16 }, Substs(tys.into()))
+            }
+            Expr::Array(array) => {
+                let elem_ty = match &expected.ty {
+                    ty_app!(TypeCtor::Array, st) | ty_app!(TypeCtor::Slice, st) => {
+                        st.as_single().clone()
+                    }
+                    _ => self.new_type_var(),
+                };
+
+                match array {
+                    Array::ElementList(items) => {
+                        for expr in items.iter() {
+                            self.infer_expr_coerce(*expr, &Expectation::has_type(elem_ty.clone()));
+                        }
+                    }
+                    Array::Repeat { initializer, repeat } => {
+                        self.infer_expr_coerce(
+                            *initializer,
+                            &Expectation::has_type(elem_ty.clone()),
+                        );
+                        self.infer_expr(
+                            *repeat,
+                            &Expectation::has_type(Ty::simple(TypeCtor::Int(Uncertain::Known(
+                                IntTy::usize(),
+                            )))),
+                        );
+                    }
+                }
+
+                Ty::apply_one(TypeCtor::Array, elem_ty)
+            }
+            Expr::Literal(lit) => match lit {
+                Literal::Bool(..) => Ty::simple(TypeCtor::Bool),
+                Literal::String(..) => {
+                    Ty::apply_one(TypeCtor::Ref(Mutability::Shared), Ty::simple(TypeCtor::Str))
+                }
+                Literal::ByteString(..) => {
+                    let byte_type = Ty::simple(TypeCtor::Int(Uncertain::Known(IntTy::u8())));
+                    let slice_type = Ty::apply_one(TypeCtor::Slice, byte_type);
+                    Ty::apply_one(TypeCtor::Ref(Mutability::Shared), slice_type)
+                }
+                Literal::Char(..) => Ty::simple(TypeCtor::Char),
+                Literal::Int(_v, ty) => Ty::simple(TypeCtor::Int((*ty).into())),
+                Literal::Float(_v, ty) => Ty::simple(TypeCtor::Float((*ty).into())),
+            },
+        };
+        // use a new type variable if we got Ty::Unknown here
+        let ty = self.insert_type_vars_shallow(ty);
+        let ty = self.resolve_ty_as_possible(&mut vec![], ty);
+        self.write_expr_ty(tgt_expr, ty.clone());
+        ty
+    }
+
+    fn infer_block(
+        &mut self,
+        statements: &[Statement],
+        tail: Option<ExprId>,
+        expected: &Expectation,
+    ) -> Ty {
+        let mut diverges = false;
+        for stmt in statements {
+            match stmt {
+                Statement::Let { pat, type_ref, initializer } => {
+                    let decl_ty =
+                        type_ref.as_ref().map(|tr| self.make_ty(tr)).unwrap_or(Ty::Unknown);
+
+                    // Always use the declared type when specified
+                    let mut ty = decl_ty.clone();
+
+                    if let Some(expr) = initializer {
+                        let actual_ty =
+                            self.infer_expr_coerce(*expr, &Expectation::has_type(decl_ty.clone()));
+                        if decl_ty == Ty::Unknown {
+                            ty = actual_ty;
+                        }
+                    }
+
+                    let ty = self.resolve_ty_as_possible(&mut vec![], ty);
+                    self.infer_pat(*pat, &ty, BindingMode::default());
+                }
+                Statement::Expr(expr) => {
+                    if let ty_app!(TypeCtor::Never) = self.infer_expr(*expr, &Expectation::none()) {
+                        diverges = true;
+                    }
+                }
+            }
+        }
+
+        let ty = if let Some(expr) = tail {
+            self.infer_expr_coerce(expr, expected)
+        } else {
+            self.coerce(&Ty::unit(), &expected.ty);
+            Ty::unit()
+        };
+        if diverges {
+            Ty::simple(TypeCtor::Never)
+        } else {
+            ty
+        }
+    }
+
+    fn infer_method_call(
+        &mut self,
+        tgt_expr: ExprId,
+        receiver: ExprId,
+        args: &[ExprId],
+        method_name: &Name,
+        generic_args: Option<&GenericArgs>,
+    ) -> Ty {
+        let receiver_ty = self.infer_expr(receiver, &Expectation::none());
+        let canonicalized_receiver = self.canonicalizer().canonicalize_ty(receiver_ty.clone());
+        let resolved = method_resolution::lookup_method(
+            &canonicalized_receiver.value,
+            self.db,
+            method_name,
+            &self.resolver,
+        );
+        let (derefed_receiver_ty, method_ty, def_generics) = match resolved {
+            Some((ty, func)) => {
+                let ty = canonicalized_receiver.decanonicalize_ty(ty);
+                self.write_method_resolution(tgt_expr, func);
+                (ty, self.db.value_ty(func.into()), Some(self.db.generic_params(func.into())))
+            }
+            None => (receiver_ty, Ty::Unknown, None),
+        };
+        let substs = self.substs_for_method_call(def_generics, generic_args, &derefed_receiver_ty);
+        let method_ty = method_ty.apply_substs(substs);
+        let method_ty = self.insert_type_vars(method_ty);
+        self.register_obligations_for_call(&method_ty);
+        let (expected_receiver_ty, param_tys, ret_ty) = match method_ty.callable_sig(self.db) {
+            Some(sig) => {
+                if !sig.params().is_empty() {
+                    (sig.params()[0].clone(), sig.params()[1..].to_vec(), sig.ret().clone())
+                } else {
+                    (Ty::Unknown, Vec::new(), sig.ret().clone())
+                }
+            }
+            None => (Ty::Unknown, Vec::new(), Ty::Unknown),
+        };
+        // Apply autoref so the below unification works correctly
+        // FIXME: return correct autorefs from lookup_method
+        let actual_receiver_ty = match expected_receiver_ty.as_reference() {
+            Some((_, mutability)) => Ty::apply_one(TypeCtor::Ref(mutability), derefed_receiver_ty),
+            _ => derefed_receiver_ty,
+        };
+        self.unify(&expected_receiver_ty, &actual_receiver_ty);
+
+        self.check_call_arguments(args, &param_tys);
+        let ret_ty = self.normalize_associated_types_in(ret_ty);
+        ret_ty
+    }
+
+    fn check_call_arguments(&mut self, args: &[ExprId], param_tys: &[Ty]) {
+        // Quoting https://github.com/rust-lang/rust/blob/6ef275e6c3cb1384ec78128eceeb4963ff788dca/src/librustc_typeck/check/mod.rs#L3325 --
+        // We do this in a pretty awful way: first we type-check any arguments
+        // that are not closures, then we type-check the closures. This is so
+        // that we have more information about the types of arguments when we
+        // type-check the functions. This isn't really the right way to do this.
+        for &check_closures in &[false, true] {
+            let param_iter = param_tys.iter().cloned().chain(repeat(Ty::Unknown));
+            for (&arg, param_ty) in args.iter().zip(param_iter) {
+                let is_closure = match &self.body[arg] {
+                    Expr::Lambda { .. } => true,
+                    _ => false,
+                };
+
+                if is_closure != check_closures {
+                    continue;
+                }
+
+                let param_ty = self.normalize_associated_types_in(param_ty);
+                self.infer_expr_coerce(arg, &Expectation::has_type(param_ty.clone()));
+            }
+        }
+    }
+
+    fn substs_for_method_call(
+        &mut self,
+        def_generics: Option<Arc<GenericParams>>,
+        generic_args: Option<&GenericArgs>,
+        receiver_ty: &Ty,
+    ) -> Substs {
+        let (parent_param_count, param_count) =
+            def_generics.as_ref().map_or((0, 0), |g| (g.count_parent_params(), g.params.len()));
+        let mut substs = Vec::with_capacity(parent_param_count + param_count);
+        // Parent arguments are unknown, except for the receiver type
+        if let Some(parent_generics) = def_generics.and_then(|p| p.parent_params.clone()) {
+            for param in &parent_generics.params {
+                if param.name == name::SELF_TYPE {
+                    substs.push(receiver_ty.clone());
+                } else {
+                    substs.push(Ty::Unknown);
+                }
+            }
+        }
+        // handle provided type arguments
+        if let Some(generic_args) = generic_args {
+            // if args are provided, it should be all of them, but we can't rely on that
+            for arg in generic_args.args.iter().take(param_count) {
+                match arg {
+                    GenericArg::Type(type_ref) => {
+                        let ty = self.make_ty(type_ref);
+                        substs.push(ty);
+                    }
+                }
+            }
+        };
+        let supplied_params = substs.len();
+        for _ in supplied_params..parent_param_count + param_count {
+            substs.push(Ty::Unknown);
+        }
+        assert_eq!(substs.len(), parent_param_count + param_count);
+        Substs(substs.into())
+    }
+
+    fn register_obligations_for_call(&mut self, callable_ty: &Ty) {
+        if let Ty::Apply(a_ty) = callable_ty {
+            if let TypeCtor::FnDef(def) = a_ty.ctor {
+                let generic_predicates = self.db.generic_predicates(def.into());
+                for predicate in generic_predicates.iter() {
+                    let predicate = predicate.clone().subst(&a_ty.parameters);
+                    if let Some(obligation) = Obligation::from_predicate(predicate) {
+                        self.obligations.push(obligation);
+                    }
+                }
+                // add obligation for trait implementation, if this is a trait method
+                match def {
+                    CallableDef::FunctionId(f) => {
+                        if let ContainerId::TraitId(trait_) = f.lookup(self.db).container {
+                            // construct a TraitDef
+                            let substs = a_ty.parameters.prefix(
+                                self.db
+                                    .generic_params(trait_.into())
+                                    .count_params_including_parent(),
+                            );
+                            self.obligations.push(Obligation::Trait(TraitRef {
+                                trait_: trait_.into(),
+                                substs,
+                            }));
+                        }
+                    }
+                    CallableDef::StructId(_) | CallableDef::EnumVariantId(_) => {}
+                }
+            }
+        }
+    }
+}
diff --git a/crates/ra_hir_ty/src/infer/pat.rs b/crates/ra_hir_ty/src/infer/pat.rs
new file mode 100644
index 000000000..1ebb36239
--- /dev/null
+++ b/crates/ra_hir_ty/src/infer/pat.rs
@@ -0,0 +1,186 @@
+//! Type inference for patterns.
+
+use std::iter::repeat;
+use std::sync::Arc;
+
+use hir_def::{
+    expr::{BindingAnnotation, Pat, PatId, RecordFieldPat},
+    path::Path,
+    type_ref::Mutability,
+};
+use hir_expand::name::Name;
+use test_utils::tested_by;
+
+use super::{BindingMode, InferenceContext};
+use crate::{db::HirDatabase, utils::variant_data, Substs, Ty, TypeCtor, TypeWalk};
+
+impl<'a, D: HirDatabase> InferenceContext<'a, D> {
+    fn infer_tuple_struct_pat(
+        &mut self,
+        path: Option<&Path>,
+        subpats: &[PatId],
+        expected: &Ty,
+        default_bm: BindingMode,
+    ) -> Ty {
+        let (ty, def) = self.resolve_variant(path);
+        let var_data = def.map(|it| variant_data(self.db, it));
+        self.unify(&ty, expected);
+
+        let substs = ty.substs().unwrap_or_else(Substs::empty);
+
+        let field_tys = def.map(|it| self.db.field_types(it.into())).unwrap_or_default();
+
+        for (i, &subpat) in subpats.iter().enumerate() {
+            let expected_ty = var_data
+                .as_ref()
+                .and_then(|d| d.field(&Name::new_tuple_field(i)))
+                .map_or(Ty::Unknown, |field| field_tys[field].clone())
+                .subst(&substs);
+            let expected_ty = self.normalize_associated_types_in(expected_ty);
+            self.infer_pat(subpat, &expected_ty, default_bm);
+        }
+
+        ty
+    }
+
+    fn infer_record_pat(
+        &mut self,
+        path: Option<&Path>,
+        subpats: &[RecordFieldPat],
+        expected: &Ty,
+        default_bm: BindingMode,
+        id: PatId,
+    ) -> Ty {
+        let (ty, def) = self.resolve_variant(path);
+        let var_data = def.map(|it| variant_data(self.db, it));
+        if let Some(variant) = def {
+            self.write_variant_resolution(id.into(), variant);
+        }
+
+        self.unify(&ty, expected);
+
+        let substs = ty.substs().unwrap_or_else(Substs::empty);
+
+        let field_tys = def.map(|it| self.db.field_types(it.into())).unwrap_or_default();
+        for subpat in subpats {
+            let matching_field = var_data.as_ref().and_then(|it| it.field(&subpat.name));
+            let expected_ty =
+                matching_field.map_or(Ty::Unknown, |field| field_tys[field].clone()).subst(&substs);
+            let expected_ty = self.normalize_associated_types_in(expected_ty);
+            self.infer_pat(subpat.pat, &expected_ty, default_bm);
+        }
+
+        ty
+    }
+
+    pub(super) fn infer_pat(
+        &mut self,
+        pat: PatId,
+        mut expected: &Ty,
+        mut default_bm: BindingMode,
+    ) -> Ty {
+        let body = Arc::clone(&self.body); // avoid borrow checker problem
+
+        let is_non_ref_pat = match &body[pat] {
+            Pat::Tuple(..)
+            | Pat::TupleStruct { .. }
+            | Pat::Record { .. }
+            | Pat::Range { .. }
+            | Pat::Slice { .. } => true,
+            // FIXME: Path/Lit might actually evaluate to ref, but inference is unimplemented.
+            Pat::Path(..) | Pat::Lit(..) => true,
+            Pat::Wild | Pat::Bind { .. } | Pat::Ref { .. } | Pat::Missing => false,
+        };
+        if is_non_ref_pat {
+            while let Some((inner, mutability)) = expected.as_reference() {
+                expected = inner;
+                default_bm = match default_bm {
+                    BindingMode::Move => BindingMode::Ref(mutability),
+                    BindingMode::Ref(Mutability::Shared) => BindingMode::Ref(Mutability::Shared),
+                    BindingMode::Ref(Mutability::Mut) => BindingMode::Ref(mutability),
+                }
+            }
+        } else if let Pat::Ref { .. } = &body[pat] {
+            tested_by!(match_ergonomics_ref);
+            // When you encounter a `&pat` pattern, reset to Move.
+            // This is so that `w` is by value: `let (_, &w) = &(1, &2);`
+            default_bm = BindingMode::Move;
+        }
+
+        // Lose mutability.
+        let default_bm = default_bm;
+        let expected = expected;
+
+        let ty = match &body[pat] {
+            Pat::Tuple(ref args) => {
+                let expectations = match expected.as_tuple() {
+                    Some(parameters) => &*parameters.0,
+                    _ => &[],
+                };
+                let expectations_iter = expectations.iter().chain(repeat(&Ty::Unknown));
+
+                let inner_tys = args
+                    .iter()
+                    .zip(expectations_iter)
+                    .map(|(&pat, ty)| self.infer_pat(pat, ty, default_bm))
+                    .collect();
+
+                Ty::apply(TypeCtor::Tuple { cardinality: args.len() as u16 }, Substs(inner_tys))
+            }
+            Pat::Ref { pat, mutability } => {
+                let expectation = match expected.as_reference() {
+                    Some((inner_ty, exp_mut)) => {
+                        if *mutability != exp_mut {
+                            // FIXME: emit type error?
+                        }
+                        inner_ty
+                    }
+                    _ => &Ty::Unknown,
+                };
+                let subty = self.infer_pat(*pat, expectation, default_bm);
+                Ty::apply_one(TypeCtor::Ref(*mutability), subty)
+            }
+            Pat::TupleStruct { path: p, args: subpats } => {
+                self.infer_tuple_struct_pat(p.as_ref(), subpats, expected, default_bm)
+            }
+            Pat::Record { path: p, args: fields } => {
+                self.infer_record_pat(p.as_ref(), fields, expected, default_bm, pat)
+            }
+            Pat::Path(path) => {
+                // FIXME use correct resolver for the surrounding expression
+                let resolver = self.resolver.clone();
+                self.infer_path(&resolver, &path, pat.into()).unwrap_or(Ty::Unknown)
+            }
+            Pat::Bind { mode, name: _, subpat } => {
+                let mode = if mode == &BindingAnnotation::Unannotated {
+                    default_bm
+                } else {
+                    BindingMode::convert(*mode)
+                };
+                let inner_ty = if let Some(subpat) = subpat {
+                    self.infer_pat(*subpat, expected, default_bm)
+                } else {
+                    expected.clone()
+                };
+                let inner_ty = self.insert_type_vars_shallow(inner_ty);
+
+                let bound_ty = match mode {
+                    BindingMode::Ref(mutability) => {
+                        Ty::apply_one(TypeCtor::Ref(mutability), inner_ty.clone())
+                    }
+                    BindingMode::Move => inner_ty.clone(),
+                };
+                let bound_ty = self.resolve_ty_as_possible(&mut vec![], bound_ty);
+                self.write_pat_ty(pat, bound_ty);
+                return inner_ty;
+            }
+            _ => Ty::Unknown,
+        };
+        // use a new type variable if we got Ty::Unknown here
+        let ty = self.insert_type_vars_shallow(ty);
+        self.unify(&ty, expected);
+        let ty = self.resolve_ty_as_possible(&mut vec![], ty);
+        self.write_pat_ty(pat, ty.clone());
+        ty
+    }
+}
diff --git a/crates/ra_hir_ty/src/infer/path.rs b/crates/ra_hir_ty/src/infer/path.rs
new file mode 100644
index 000000000..14be66836
--- /dev/null
+++ b/crates/ra_hir_ty/src/infer/path.rs
@@ -0,0 +1,268 @@
+//! Path expression resolution.
+
+use hir_def::{
+    path::{Path, PathKind, PathSegment},
+    resolver::{ResolveValueResult, Resolver, TypeNs, ValueNs},
+    AssocItemId, ContainerId, Lookup,
+};
+use hir_expand::name::Name;
+
+use crate::{db::HirDatabase, method_resolution, Substs, Ty, TypeWalk, ValueTyDefId};
+
+use super::{ExprOrPatId, InferenceContext, TraitRef};
+
+impl<'a, D: HirDatabase> InferenceContext<'a, D> {
+    pub(super) fn infer_path(
+        &mut self,
+        resolver: &Resolver,
+        path: &Path,
+        id: ExprOrPatId,
+    ) -> Option<Ty> {
+        let ty = self.resolve_value_path(resolver, path, id)?;
+        let ty = self.insert_type_vars(ty);
+        let ty = self.normalize_associated_types_in(ty);
+        Some(ty)
+    }
+
+    fn resolve_value_path(
+        &mut self,
+        resolver: &Resolver,
+        path: &Path,
+        id: ExprOrPatId,
+    ) -> Option<Ty> {
+        let (value, self_subst) = if let PathKind::Type(type_ref) = &path.kind {
+            if path.segments.is_empty() {
+                // This can't actually happen syntax-wise
+                return None;
+            }
+            let ty = self.make_ty(type_ref);
+            let remaining_segments_for_ty = &path.segments[..path.segments.len() - 1];
+            let ty = Ty::from_type_relative_path(self.db, resolver, ty, remaining_segments_for_ty);
+            self.resolve_ty_assoc_item(
+                ty,
+                &path.segments.last().expect("path had at least one segment").name,
+                id,
+            )?
+        } else {
+            let value_or_partial = resolver.resolve_path_in_value_ns(self.db, &path)?;
+
+            match value_or_partial {
+                ResolveValueResult::ValueNs(it) => (it, None),
+                ResolveValueResult::Partial(def, remaining_index) => {
+                    self.resolve_assoc_item(def, path, remaining_index, id)?
+                }
+            }
+        };
+
+        let typable: ValueTyDefId = match value {
+            ValueNs::LocalBinding(pat) => {
+                let ty = self.result.type_of_pat.get(pat)?.clone();
+                let ty = self.resolve_ty_as_possible(&mut vec![], ty);
+                return Some(ty);
+            }
+            ValueNs::FunctionId(it) => it.into(),
+            ValueNs::ConstId(it) => it.into(),
+            ValueNs::StaticId(it) => it.into(),
+            ValueNs::StructId(it) => it.into(),
+            ValueNs::EnumVariantId(it) => it.into(),
+        };
+
+        let mut ty = self.db.value_ty(typable);
+        if let Some(self_subst) = self_subst {
+            ty = ty.subst(&self_subst);
+        }
+        let substs = Ty::substs_from_path(self.db, &self.resolver, path, typable);
+        let ty = ty.subst(&substs);
+        Some(ty)
+    }
+
+    fn resolve_assoc_item(
+        &mut self,
+        def: TypeNs,
+        path: &Path,
+        remaining_index: usize,
+        id: ExprOrPatId,
+    ) -> Option<(ValueNs, Option<Substs>)> {
+        assert!(remaining_index < path.segments.len());
+        // there may be more intermediate segments between the resolved one and
+        // the end. Only the last segment needs to be resolved to a value; from
+        // the segments before that, we need to get either a type or a trait ref.
+
+        let resolved_segment = &path.segments[remaining_index - 1];
+        let remaining_segments = &path.segments[remaining_index..];
+        let is_before_last = remaining_segments.len() == 1;
+
+        match (def, is_before_last) {
+            (TypeNs::TraitId(trait_), true) => {
+                let segment =
+                    remaining_segments.last().expect("there should be at least one segment here");
+                let trait_ref = TraitRef::from_resolved_path(
+                    self.db,
+                    &self.resolver,
+                    trait_.into(),
+                    resolved_segment,
+                    None,
+                );
+                self.resolve_trait_assoc_item(trait_ref, segment, id)
+            }
+            (def, _) => {
+                // Either we already have a type (e.g. `Vec::new`), or we have a
+                // trait but it's not the last segment, so the next segment
+                // should resolve to an associated type of that trait (e.g. `<T
+                // as Iterator>::Item::default`)
+                let remaining_segments_for_ty = &remaining_segments[..remaining_segments.len() - 1];
+                let ty = Ty::from_partly_resolved_hir_path(
+                    self.db,
+                    &self.resolver,
+                    def,
+                    resolved_segment,
+                    remaining_segments_for_ty,
+                );
+                if let Ty::Unknown = ty {
+                    return None;
+                }
+
+                let ty = self.insert_type_vars(ty);
+                let ty = self.normalize_associated_types_in(ty);
+
+                let segment =
+                    remaining_segments.last().expect("there should be at least one segment here");
+
+                self.resolve_ty_assoc_item(ty, &segment.name, id)
+            }
+        }
+    }
+
+    fn resolve_trait_assoc_item(
+        &mut self,
+        trait_ref: TraitRef,
+        segment: &PathSegment,
+        id: ExprOrPatId,
+    ) -> Option<(ValueNs, Option<Substs>)> {
+        let trait_ = trait_ref.trait_;
+        let item = self
+            .db
+            .trait_data(trait_)
+            .items
+            .iter()
+            .map(|(_name, id)| (*id).into())
+            .find_map(|item| match item {
+                AssocItemId::FunctionId(func) => {
+                    if segment.name == self.db.function_data(func).name {
+                        Some(AssocItemId::FunctionId(func))
+                    } else {
+                        None
+                    }
+                }
+
+                AssocItemId::ConstId(konst) => {
+                    if self.db.const_data(konst).name.as_ref().map_or(false, |n| n == &segment.name)
+                    {
+                        Some(AssocItemId::ConstId(konst))
+                    } else {
+                        None
+                    }
+                }
+                AssocItemId::TypeAliasId(_) => None,
+            })?;
+        let def = match item {
+            AssocItemId::FunctionId(f) => ValueNs::FunctionId(f),
+            AssocItemId::ConstId(c) => ValueNs::ConstId(c),
+            AssocItemId::TypeAliasId(_) => unreachable!(),
+        };
+        let substs = Substs::build_for_def(self.db, item)
+            .use_parent_substs(&trait_ref.substs)
+            .fill_with_params()
+            .build();
+
+        self.write_assoc_resolution(id, item);
+        Some((def, Some(substs)))
+    }
+
+    fn resolve_ty_assoc_item(
+        &mut self,
+        ty: Ty,
+        name: &Name,
+        id: ExprOrPatId,
+    ) -> Option<(ValueNs, Option<Substs>)> {
+        if let Ty::Unknown = ty {
+            return None;
+        }
+
+        let canonical_ty = self.canonicalizer().canonicalize_ty(ty.clone());
+
+        method_resolution::iterate_method_candidates(
+            &canonical_ty.value,
+            self.db,
+            &self.resolver.clone(),
+            Some(name),
+            method_resolution::LookupMode::Path,
+            move |_ty, item| {
+                let (def, container) = match item {
+                    AssocItemId::FunctionId(f) => {
+                        (ValueNs::FunctionId(f), f.lookup(self.db).container)
+                    }
+                    AssocItemId::ConstId(c) => (ValueNs::ConstId(c), c.lookup(self.db).container),
+                    AssocItemId::TypeAliasId(_) => unreachable!(),
+                };
+                let substs = match container {
+                    ContainerId::ImplId(_) => self.find_self_types(&def, ty.clone()),
+                    ContainerId::TraitId(trait_) => {
+                        // we're picking this method
+                        let trait_substs = Substs::build_for_def(self.db, trait_)
+                            .push(ty.clone())
+                            .fill(std::iter::repeat_with(|| self.new_type_var()))
+                            .build();
+                        let substs = Substs::build_for_def(self.db, item)
+                            .use_parent_substs(&trait_substs)
+                            .fill_with_params()
+                            .build();
+                        self.obligations.push(super::Obligation::Trait(TraitRef {
+                            trait_,
+                            substs: trait_substs,
+                        }));
+                        Some(substs)
+                    }
+                    ContainerId::ModuleId(_) => None,
+                };
+
+                self.write_assoc_resolution(id, item.into());
+                Some((def, substs))
+            },
+        )
+    }
+
+    fn find_self_types(&self, def: &ValueNs, actual_def_ty: Ty) -> Option<Substs> {
+        if let ValueNs::FunctionId(func) = *def {
+            // We only do the infer if parent has generic params
+            let gen = self.db.generic_params(func.into());
+            if gen.count_parent_params() == 0 {
+                return None;
+            }
+
+            let impl_id = match func.lookup(self.db).container {
+                ContainerId::ImplId(it) => it,
+                _ => return None,
+            };
+            let self_ty = self.db.impl_ty(impl_id).self_type().clone();
+            let self_ty_substs = self_ty.substs()?;
+            let actual_substs = actual_def_ty.substs()?;
+
+            let mut new_substs = vec![Ty::Unknown; gen.count_parent_params()];
+
+            // The following code *link up* the function actual parma type
+            // and impl_block type param index
+            self_ty_substs.iter().zip(actual_substs.iter()).for_each(|(param, pty)| {
+                if let Ty::Param { idx, .. } = param {
+                    if let Some(s) = new_substs.get_mut(*idx as usize) {
+                        *s = pty.clone();
+                    }
+                }
+            });
+
+            Some(Substs(new_substs.into()))
+        } else {
+            None
+        }
+    }
+}
diff --git a/crates/ra_hir_ty/src/infer/unify.rs b/crates/ra_hir_ty/src/infer/unify.rs
new file mode 100644
index 000000000..f3a875678
--- /dev/null
+++ b/crates/ra_hir_ty/src/infer/unify.rs
@@ -0,0 +1,162 @@
+//! Unification and canonicalization logic.
+
+use super::{InferenceContext, Obligation};
+use crate::{
+    db::HirDatabase, utils::make_mut_slice, Canonical, InEnvironment, InferTy, ProjectionPredicate,
+    ProjectionTy, Substs, TraitRef, Ty, TypeWalk,
+};
+
+impl<'a, D: HirDatabase> InferenceContext<'a, D> {
+    pub(super) fn canonicalizer<'b>(&'b mut self) -> Canonicalizer<'a, 'b, D>
+    where
+        'a: 'b,
+    {
+        Canonicalizer { ctx: self, free_vars: Vec::new(), var_stack: Vec::new() }
+    }
+}
+
+pub(super) struct Canonicalizer<'a, 'b, D: HirDatabase>
+where
+    'a: 'b,
+{
+    ctx: &'b mut InferenceContext<'a, D>,
+    free_vars: Vec<InferTy>,
+    /// A stack of type variables that is used to detect recursive types (which
+    /// are an error, but we need to protect against them to avoid stack
+    /// overflows).
+    var_stack: Vec<super::TypeVarId>,
+}
+
+pub(super) struct Canonicalized<T> {
+    pub value: Canonical<T>,
+    free_vars: Vec<InferTy>,
+}
+
+impl<'a, 'b, D: HirDatabase> Canonicalizer<'a, 'b, D>
+where
+    'a: 'b,
+{
+    fn add(&mut self, free_var: InferTy) -> usize {
+        self.free_vars.iter().position(|&v| v == free_var).unwrap_or_else(|| {
+            let next_index = self.free_vars.len();
+            self.free_vars.push(free_var);
+            next_index
+        })
+    }
+
+    fn do_canonicalize_ty(&mut self, ty: Ty) -> Ty {
+        ty.fold(&mut |ty| match ty {
+            Ty::Infer(tv) => {
+                let inner = tv.to_inner();
+                if self.var_stack.contains(&inner) {
+                    // recursive type
+                    return tv.fallback_value();
+                }
+                if let Some(known_ty) =
+                    self.ctx.var_unification_table.inlined_probe_value(inner).known()
+                {
+                    self.var_stack.push(inner);
+                    let result = self.do_canonicalize_ty(known_ty.clone());
+                    self.var_stack.pop();
+                    result
+                } else {
+                    let root = self.ctx.var_unification_table.find(inner);
+                    let free_var = match tv {
+                        InferTy::TypeVar(_) => InferTy::TypeVar(root),
+                        InferTy::IntVar(_) => InferTy::IntVar(root),
+                        InferTy::FloatVar(_) => InferTy::FloatVar(root),
+                        InferTy::MaybeNeverTypeVar(_) => InferTy::MaybeNeverTypeVar(root),
+                    };
+                    let position = self.add(free_var);
+                    Ty::Bound(position as u32)
+                }
+            }
+            _ => ty,
+        })
+    }
+
+    fn do_canonicalize_trait_ref(&mut self, mut trait_ref: TraitRef) -> TraitRef {
+        for ty in make_mut_slice(&mut trait_ref.substs.0) {
+            *ty = self.do_canonicalize_ty(ty.clone());
+        }
+        trait_ref
+    }
+
+    fn into_canonicalized<T>(self, result: T) -> Canonicalized<T> {
+        Canonicalized {
+            value: Canonical { value: result, num_vars: self.free_vars.len() },
+            free_vars: self.free_vars,
+        }
+    }
+
+    fn do_canonicalize_projection_ty(&mut self, mut projection_ty: ProjectionTy) -> ProjectionTy {
+        for ty in make_mut_slice(&mut projection_ty.parameters.0) {
+            *ty = self.do_canonicalize_ty(ty.clone());
+        }
+        projection_ty
+    }
+
+    fn do_canonicalize_projection_predicate(
+        &mut self,
+        projection: ProjectionPredicate,
+    ) -> ProjectionPredicate {
+        let ty = self.do_canonicalize_ty(projection.ty);
+        let projection_ty = self.do_canonicalize_projection_ty(projection.projection_ty);
+
+        ProjectionPredicate { ty, projection_ty }
+    }
+
+    // FIXME: add some point, we need to introduce a `Fold` trait that abstracts
+    // over all the things that can be canonicalized (like Chalk and rustc have)
+
+    pub(crate) fn canonicalize_ty(mut self, ty: Ty) -> Canonicalized<Ty> {
+        let result = self.do_canonicalize_ty(ty);
+        self.into_canonicalized(result)
+    }
+
+    pub(crate) fn canonicalize_obligation(
+        mut self,
+        obligation: InEnvironment<Obligation>,
+    ) -> Canonicalized<InEnvironment<Obligation>> {
+        let result = match obligation.value {
+            Obligation::Trait(tr) => Obligation::Trait(self.do_canonicalize_trait_ref(tr)),
+            Obligation::Projection(pr) => {
+                Obligation::Projection(self.do_canonicalize_projection_predicate(pr))
+            }
+        };
+        self.into_canonicalized(InEnvironment {
+            value: result,
+            environment: obligation.environment,
+        })
+    }
+}
+
+impl<T> Canonicalized<T> {
+    pub fn decanonicalize_ty(&self, mut ty: Ty) -> Ty {
+        ty.walk_mut_binders(
+            &mut |ty, binders| match ty {
+                &mut Ty::Bound(idx) => {
+                    if idx as usize >= binders && (idx as usize - binders) < self.free_vars.len() {
+                        *ty = Ty::Infer(self.free_vars[idx as usize - binders]);
+                    }
+                }
+                _ => {}
+            },
+            0,
+        );
+        ty
+    }
+
+    pub fn apply_solution(
+        &self,
+        ctx: &mut InferenceContext<'_, impl HirDatabase>,
+        solution: Canonical<Vec<Ty>>,
+    ) {
+        // the solution may contain new variables, which we need to convert to new inference vars
+        let new_vars = Substs((0..solution.num_vars).map(|_| ctx.new_type_var()).collect());
+        for (i, ty) in solution.value.into_iter().enumerate() {
+            let var = self.free_vars[i];
+            ctx.unify(&Ty::Infer(var), &ty.subst_bound_vars(&new_vars));
+        }
+    }
+}
diff --git a/crates/ra_hir_ty/src/lib.rs b/crates/ra_hir_ty/src/lib.rs
new file mode 100644
index 000000000..b45c8f82f
--- /dev/null
+++ b/crates/ra_hir_ty/src/lib.rs
@@ -0,0 +1,1138 @@
+//! The type system. We currently use this to infer types for completion, hover
+//! information and various assists.
+
+macro_rules! impl_froms {
+    ($e:ident: $($v:ident $(($($sv:ident),*))?),*) => {
+        $(
+            impl From<$v> for $e {
+                fn from(it: $v) -> $e {
+                    $e::$v(it)
+                }
+            }
+            $($(
+                impl From<$sv> for $e {
+                    fn from(it: $sv) -> $e {
+                        $e::$v($v::$sv(it))
+                    }
+                }
+            )*)?
+        )*
+    }
+}
+
+mod autoderef;
+pub mod primitive;
+pub mod traits;
+pub mod method_resolution;
+mod op;
+mod lower;
+mod infer;
+pub mod display;
+pub(crate) mod utils;
+pub mod db;
+pub mod diagnostics;
+pub mod expr;
+
+#[cfg(test)]
+mod tests;
+#[cfg(test)]
+mod test_db;
+mod marks;
+
+use std::ops::Deref;
+use std::sync::Arc;
+use std::{fmt, iter, mem};
+
+use hir_def::{
+    expr::ExprId, generics::GenericParams, type_ref::Mutability, AdtId, ContainerId, DefWithBodyId,
+    GenericDefId, HasModule, Lookup, TraitId, TypeAliasId,
+};
+use hir_expand::name::Name;
+use ra_db::{impl_intern_key, salsa, CrateId};
+
+use crate::{
+    db::HirDatabase,
+    primitive::{FloatTy, IntTy, Uncertain},
+    utils::make_mut_slice,
+};
+use display::{HirDisplay, HirFormatter};
+
+pub use autoderef::autoderef;
+pub use infer::{infer_query, InferTy, InferenceResult};
+pub use lower::CallableDef;
+pub use lower::{callable_item_sig, TyDefId, ValueTyDefId};
+pub use traits::{InEnvironment, Obligation, ProjectionPredicate, TraitEnvironment};
+
+/// A type constructor or type name: this might be something like the primitive
+/// type `bool`, a struct like `Vec`, or things like function pointers or
+/// tuples.
+#[derive(Copy, Clone, PartialEq, Eq, Debug, Hash)]
+pub enum TypeCtor {
+    /// The primitive boolean type. Written as `bool`.
+    Bool,
+
+    /// The primitive character type; holds a Unicode scalar value
+    /// (a non-surrogate code point). Written as `char`.
+    Char,
+
+    /// A primitive integer type. For example, `i32`.
+    Int(Uncertain<IntTy>),
+
+    /// A primitive floating-point type. For example, `f64`.
+    Float(Uncertain<FloatTy>),
+
+    /// Structures, enumerations and unions.
+    Adt(AdtId),
+
+    /// The pointee of a string slice. Written as `str`.
+    Str,
+
+    /// The pointee of an array slice.  Written as `[T]`.
+    Slice,
+
+    /// An array with the given length. Written as `[T; n]`.
+    Array,
+
+    /// A raw pointer. Written as `*mut T` or `*const T`
+    RawPtr(Mutability),
+
+    /// A reference; a pointer with an associated lifetime. Written as
+    /// `&'a mut T` or `&'a T`.
+    Ref(Mutability),
+
+    /// The anonymous type of a function declaration/definition. Each
+    /// function has a unique type, which is output (for a function
+    /// named `foo` returning an `i32`) as `fn() -> i32 {foo}`.
+    ///
+    /// This includes tuple struct / enum variant constructors as well.
+    ///
+    /// For example the type of `bar` here:
+    ///
+    /// ```
+    /// fn foo() -> i32 { 1 }
+    /// let bar = foo; // bar: fn() -> i32 {foo}
+    /// ```
+    FnDef(CallableDef),
+
+    /// A pointer to a function.  Written as `fn() -> i32`.
+    ///
+    /// For example the type of `bar` here:
+    ///
+    /// ```
+    /// fn foo() -> i32 { 1 }
+    /// let bar: fn() -> i32 = foo;
+    /// ```
+    FnPtr { num_args: u16 },
+
+    /// The never type `!`.
+    Never,
+
+    /// A tuple type.  For example, `(i32, bool)`.
+    Tuple { cardinality: u16 },
+
+    /// Represents an associated item like `Iterator::Item`.  This is used
+    /// when we have tried to normalize a projection like `T::Item` but
+    /// couldn't find a better representation.  In that case, we generate
+    /// an **application type** like `(Iterator::Item)<T>`.
+    AssociatedType(TypeAliasId),
+
+    /// The type of a specific closure.
+    ///
+    /// The closure signature is stored in a `FnPtr` type in the first type
+    /// parameter.
+    Closure { def: DefWithBodyId, expr: ExprId },
+}
+
+/// This exists just for Chalk, because Chalk just has a single `StructId` where
+/// we have different kinds of ADTs, primitive types and special type
+/// constructors like tuples and function pointers.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct TypeCtorId(salsa::InternId);
+impl_intern_key!(TypeCtorId);
+
+impl TypeCtor {
+    pub fn num_ty_params(self, db: &impl HirDatabase) -> usize {
+        match self {
+            TypeCtor::Bool
+            | TypeCtor::Char
+            | TypeCtor::Int(_)
+            | TypeCtor::Float(_)
+            | TypeCtor::Str
+            | TypeCtor::Never => 0,
+            TypeCtor::Slice
+            | TypeCtor::Array
+            | TypeCtor::RawPtr(_)
+            | TypeCtor::Ref(_)
+            | TypeCtor::Closure { .. } // 1 param representing the signature of the closure
+            => 1,
+            TypeCtor::Adt(adt) => {
+                let generic_params = db.generic_params(AdtId::from(adt).into());
+                generic_params.count_params_including_parent()
+            }
+            TypeCtor::FnDef(callable) => {
+                let generic_params = db.generic_params(callable.into());
+                generic_params.count_params_including_parent()
+            }
+            TypeCtor::AssociatedType(type_alias) => {
+                let generic_params = db.generic_params(type_alias.into());
+                generic_params.count_params_including_parent()
+            }
+            TypeCtor::FnPtr { num_args } => num_args as usize + 1,
+            TypeCtor::Tuple { cardinality } => cardinality as usize,
+        }
+    }
+
+    pub fn krate(self, db: &impl HirDatabase) -> Option<CrateId> {
+        match self {
+            TypeCtor::Bool
+            | TypeCtor::Char
+            | TypeCtor::Int(_)
+            | TypeCtor::Float(_)
+            | TypeCtor::Str
+            | TypeCtor::Never
+            | TypeCtor::Slice
+            | TypeCtor::Array
+            | TypeCtor::RawPtr(_)
+            | TypeCtor::Ref(_)
+            | TypeCtor::FnPtr { .. }
+            | TypeCtor::Tuple { .. } => None,
+            // Closure's krate is irrelevant for coherence I would think?
+            TypeCtor::Closure { .. } => None,
+            TypeCtor::Adt(adt) => Some(adt.module(db).krate),
+            TypeCtor::FnDef(callable) => Some(callable.krate(db)),
+            TypeCtor::AssociatedType(type_alias) => Some(type_alias.lookup(db).module(db).krate),
+        }
+    }
+
+    pub fn as_generic_def(self) -> Option<GenericDefId> {
+        match self {
+            TypeCtor::Bool
+            | TypeCtor::Char
+            | TypeCtor::Int(_)
+            | TypeCtor::Float(_)
+            | TypeCtor::Str
+            | TypeCtor::Never
+            | TypeCtor::Slice
+            | TypeCtor::Array
+            | TypeCtor::RawPtr(_)
+            | TypeCtor::Ref(_)
+            | TypeCtor::FnPtr { .. }
+            | TypeCtor::Tuple { .. }
+            | TypeCtor::Closure { .. } => None,
+            TypeCtor::Adt(adt) => Some(adt.into()),
+            TypeCtor::FnDef(callable) => Some(callable.into()),
+            TypeCtor::AssociatedType(type_alias) => Some(type_alias.into()),
+        }
+    }
+}
+
+/// A nominal type with (maybe 0) type parameters. This might be a primitive
+/// type like `bool`, a struct, tuple, function pointer, reference or
+/// several other things.
+#[derive(Clone, PartialEq, Eq, Debug, Hash)]
+pub struct ApplicationTy {
+    pub ctor: TypeCtor,
+    pub parameters: Substs,
+}
+
+/// A "projection" type corresponds to an (unnormalized)
+/// projection like `<P0 as Trait<P1..Pn>>::Foo`. Note that the
+/// trait and all its parameters are fully known.
+#[derive(Clone, PartialEq, Eq, Debug, Hash)]
+pub struct ProjectionTy {
+    pub associated_ty: TypeAliasId,
+    pub parameters: Substs,
+}
+
+impl ProjectionTy {
+    pub fn trait_ref(&self, db: &impl HirDatabase) -> TraitRef {
+        TraitRef { trait_: self.trait_(db).into(), substs: self.parameters.clone() }
+    }
+
+    fn trait_(&self, db: &impl HirDatabase) -> TraitId {
+        match self.associated_ty.lookup(db).container {
+            ContainerId::TraitId(it) => it,
+            _ => panic!("projection ty without parent trait"),
+        }
+    }
+}
+
+impl TypeWalk for ProjectionTy {
+    fn walk(&self, f: &mut impl FnMut(&Ty)) {
+        self.parameters.walk(f);
+    }
+
+    fn walk_mut_binders(&mut self, f: &mut impl FnMut(&mut Ty, usize), binders: usize) {
+        self.parameters.walk_mut_binders(f, binders);
+    }
+}
+
+/// A type.
+///
+/// See also the `TyKind` enum in rustc (librustc/ty/sty.rs), which represents
+/// the same thing (but in a different way).
+///
+/// This should be cheap to clone.
+#[derive(Clone, PartialEq, Eq, Debug, Hash)]
+pub enum Ty {
+    /// A nominal type with (maybe 0) type parameters. This might be a primitive
+    /// type like `bool`, a struct, tuple, function pointer, reference or
+    /// several other things.
+    Apply(ApplicationTy),
+
+    /// A "projection" type corresponds to an (unnormalized)
+    /// projection like `<P0 as Trait<P1..Pn>>::Foo`. Note that the
+    /// trait and all its parameters are fully known.
+    Projection(ProjectionTy),
+
+    /// A type parameter; for example, `T` in `fn f<T>(x: T) {}
+    Param {
+        /// The index of the parameter (starting with parameters from the
+        /// surrounding impl, then the current function).
+        idx: u32,
+        /// The name of the parameter, for displaying.
+        // FIXME get rid of this
+        name: Name,
+    },
+
+    /// A bound type variable. Used during trait resolution to represent Chalk
+    /// variables, and in `Dyn` and `Opaque` bounds to represent the `Self` type.
+    Bound(u32),
+
+    /// A type variable used during type checking. Not to be confused with a
+    /// type parameter.
+    Infer(InferTy),
+
+    /// A trait object (`dyn Trait` or bare `Trait` in pre-2018 Rust).
+    ///
+    /// The predicates are quantified over the `Self` type, i.e. `Ty::Bound(0)`
+    /// represents the `Self` type inside the bounds. This is currently
+    /// implicit; Chalk has the `Binders` struct to make it explicit, but it
+    /// didn't seem worth the overhead yet.
+    Dyn(Arc<[GenericPredicate]>),
+
+    /// An opaque type (`impl Trait`).
+    ///
+    /// The predicates are quantified over the `Self` type; see `Ty::Dyn` for
+    /// more.
+    Opaque(Arc<[GenericPredicate]>),
+
+    /// A placeholder for a type which could not be computed; this is propagated
+    /// to avoid useless error messages. Doubles as a placeholder where type
+    /// variables are inserted before type checking, since we want to try to
+    /// infer a better type here anyway -- for the IDE use case, we want to try
+    /// to infer as much as possible even in the presence of type errors.
+    Unknown,
+}
+
+/// A list of substitutions for generic parameters.
+#[derive(Clone, PartialEq, Eq, Debug, Hash)]
+pub struct Substs(Arc<[Ty]>);
+
+impl TypeWalk for Substs {
+    fn walk(&self, f: &mut impl FnMut(&Ty)) {
+        for t in self.0.iter() {
+            t.walk(f);
+        }
+    }
+
+    fn walk_mut_binders(&mut self, f: &mut impl FnMut(&mut Ty, usize), binders: usize) {
+        for t in make_mut_slice(&mut self.0) {
+            t.walk_mut_binders(f, binders);
+        }
+    }
+}
+
+impl Substs {
+    pub fn empty() -> Substs {
+        Substs(Arc::new([]))
+    }
+
+    pub fn single(ty: Ty) -> Substs {
+        Substs(Arc::new([ty]))
+    }
+
+    pub fn prefix(&self, n: usize) -> Substs {
+        Substs(self.0[..std::cmp::min(self.0.len(), n)].into())
+    }
+
+    pub fn as_single(&self) -> &Ty {
+        if self.0.len() != 1 {
+            panic!("expected substs of len 1, got {:?}", self);
+        }
+        &self.0[0]
+    }
+
+    /// Return Substs that replace each parameter by itself (i.e. `Ty::Param`).
+    pub fn identity(generic_params: &GenericParams) -> Substs {
+        Substs(
+            generic_params
+                .params_including_parent()
+                .into_iter()
+                .map(|p| Ty::Param { idx: p.idx, name: p.name.clone() })
+                .collect(),
+        )
+    }
+
+    /// Return Substs that replace each parameter by a bound variable.
+    pub fn bound_vars(generic_params: &GenericParams) -> Substs {
+        Substs(
+            generic_params
+                .params_including_parent()
+                .into_iter()
+                .map(|p| Ty::Bound(p.idx))
+                .collect(),
+        )
+    }
+
+    pub fn build_for_def(db: &impl HirDatabase, def: impl Into<GenericDefId>) -> SubstsBuilder {
+        let def = def.into();
+        let params = db.generic_params(def);
+        let param_count = params.count_params_including_parent();
+        Substs::builder(param_count)
+    }
+
+    pub fn build_for_generics(generic_params: &GenericParams) -> SubstsBuilder {
+        Substs::builder(generic_params.count_params_including_parent())
+    }
+
+    pub fn build_for_type_ctor(db: &impl HirDatabase, type_ctor: TypeCtor) -> SubstsBuilder {
+        Substs::builder(type_ctor.num_ty_params(db))
+    }
+
+    fn builder(param_count: usize) -> SubstsBuilder {
+        SubstsBuilder { vec: Vec::with_capacity(param_count), param_count }
+    }
+}
+
+#[derive(Debug, Clone)]
+pub struct SubstsBuilder {
+    vec: Vec<Ty>,
+    param_count: usize,
+}
+
+impl SubstsBuilder {
+    pub fn build(self) -> Substs {
+        assert_eq!(self.vec.len(), self.param_count);
+        Substs(self.vec.into())
+    }
+
+    pub fn push(mut self, ty: Ty) -> Self {
+        self.vec.push(ty);
+        self
+    }
+
+    fn remaining(&self) -> usize {
+        self.param_count - self.vec.len()
+    }
+
+    pub fn fill_with_bound_vars(self, starting_from: u32) -> Self {
+        self.fill((starting_from..).map(Ty::Bound))
+    }
+
+    pub fn fill_with_params(self) -> Self {
+        let start = self.vec.len() as u32;
+        self.fill((start..).map(|idx| Ty::Param { idx, name: Name::missing() }))
+    }
+
+    pub fn fill_with_unknown(self) -> Self {
+        self.fill(iter::repeat(Ty::Unknown))
+    }
+
+    pub fn fill(mut self, filler: impl Iterator<Item = Ty>) -> Self {
+        self.vec.extend(filler.take(self.remaining()));
+        assert_eq!(self.remaining(), 0);
+        self
+    }
+
+    pub fn use_parent_substs(mut self, parent_substs: &Substs) -> Self {
+        assert!(self.vec.is_empty());
+        assert!(parent_substs.len() <= self.param_count);
+        self.vec.extend(parent_substs.iter().cloned());
+        self
+    }
+}
+
+impl Deref for Substs {
+    type Target = [Ty];
+
+    fn deref(&self) -> &[Ty] {
+        &self.0
+    }
+}
+
+/// A trait with type parameters. This includes the `Self`, so this represents a concrete type implementing the trait.
+/// Name to be bikeshedded: TraitBound? TraitImplements?
+#[derive(Clone, PartialEq, Eq, Debug, Hash)]
+pub struct TraitRef {
+    /// FIXME name?
+    pub trait_: TraitId,
+    pub substs: Substs,
+}
+
+impl TraitRef {
+    pub fn self_ty(&self) -> &Ty {
+        &self.substs[0]
+    }
+}
+
+impl TypeWalk for TraitRef {
+    fn walk(&self, f: &mut impl FnMut(&Ty)) {
+        self.substs.walk(f);
+    }
+
+    fn walk_mut_binders(&mut self, f: &mut impl FnMut(&mut Ty, usize), binders: usize) {
+        self.substs.walk_mut_binders(f, binders);
+    }
+}
+
+#[derive(Clone, PartialEq, Eq, Debug)]
+pub enum ImplTy {
+    Inherent(Ty),
+    TraitRef(TraitRef),
+}
+
+impl ImplTy {
+    pub(crate) fn self_type(&self) -> &Ty {
+        match self {
+            ImplTy::Inherent(it) => it,
+            ImplTy::TraitRef(tr) => &tr.substs[0],
+        }
+    }
+}
+
+/// Like `generics::WherePredicate`, but with resolved types: A condition on the
+/// parameters of a generic item.
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub enum GenericPredicate {
+    /// The given trait needs to be implemented for its type parameters.
+    Implemented(TraitRef),
+    /// An associated type bindings like in `Iterator<Item = T>`.
+    Projection(ProjectionPredicate),
+    /// We couldn't resolve the trait reference. (If some type parameters can't
+    /// be resolved, they will just be Unknown).
+    Error,
+}
+
+impl GenericPredicate {
+    pub fn is_error(&self) -> bool {
+        match self {
+            GenericPredicate::Error => true,
+            _ => false,
+        }
+    }
+
+    pub fn is_implemented(&self) -> bool {
+        match self {
+            GenericPredicate::Implemented(_) => true,
+            _ => false,
+        }
+    }
+
+    pub fn trait_ref(&self, db: &impl HirDatabase) -> Option<TraitRef> {
+        match self {
+            GenericPredicate::Implemented(tr) => Some(tr.clone()),
+            GenericPredicate::Projection(proj) => Some(proj.projection_ty.trait_ref(db)),
+            GenericPredicate::Error => None,
+        }
+    }
+}
+
+impl TypeWalk for GenericPredicate {
+    fn walk(&self, f: &mut impl FnMut(&Ty)) {
+        match self {
+            GenericPredicate::Implemented(trait_ref) => trait_ref.walk(f),
+            GenericPredicate::Projection(projection_pred) => projection_pred.walk(f),
+            GenericPredicate::Error => {}
+        }
+    }
+
+    fn walk_mut_binders(&mut self, f: &mut impl FnMut(&mut Ty, usize), binders: usize) {
+        match self {
+            GenericPredicate::Implemented(trait_ref) => trait_ref.walk_mut_binders(f, binders),
+            GenericPredicate::Projection(projection_pred) => {
+                projection_pred.walk_mut_binders(f, binders)
+            }
+            GenericPredicate::Error => {}
+        }
+    }
+}
+
+/// Basically a claim (currently not validated / checked) that the contained
+/// type / trait ref contains no inference variables; any inference variables it
+/// contained have been replaced by bound variables, and `num_vars` tells us how
+/// many there are. This is used to erase irrelevant differences between types
+/// before using them in queries.
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub struct Canonical<T> {
+    pub value: T,
+    pub num_vars: usize,
+}
+
+/// A function signature as seen by type inference: Several parameter types and
+/// one return type.
+#[derive(Clone, PartialEq, Eq, Debug)]
+pub struct FnSig {
+    params_and_return: Arc<[Ty]>,
+}
+
+impl FnSig {
+    pub fn from_params_and_return(mut params: Vec<Ty>, ret: Ty) -> FnSig {
+        params.push(ret);
+        FnSig { params_and_return: params.into() }
+    }
+
+    pub fn from_fn_ptr_substs(substs: &Substs) -> FnSig {
+        FnSig { params_and_return: Arc::clone(&substs.0) }
+    }
+
+    pub fn params(&self) -> &[Ty] {
+        &self.params_and_return[0..self.params_and_return.len() - 1]
+    }
+
+    pub fn ret(&self) -> &Ty {
+        &self.params_and_return[self.params_and_return.len() - 1]
+    }
+}
+
+impl TypeWalk for FnSig {
+    fn walk(&self, f: &mut impl FnMut(&Ty)) {
+        for t in self.params_and_return.iter() {
+            t.walk(f);
+        }
+    }
+
+    fn walk_mut_binders(&mut self, f: &mut impl FnMut(&mut Ty, usize), binders: usize) {
+        for t in make_mut_slice(&mut self.params_and_return) {
+            t.walk_mut_binders(f, binders);
+        }
+    }
+}
+
+impl Ty {
+    pub fn simple(ctor: TypeCtor) -> Ty {
+        Ty::Apply(ApplicationTy { ctor, parameters: Substs::empty() })
+    }
+    pub fn apply_one(ctor: TypeCtor, param: Ty) -> Ty {
+        Ty::Apply(ApplicationTy { ctor, parameters: Substs::single(param) })
+    }
+    pub fn apply(ctor: TypeCtor, parameters: Substs) -> Ty {
+        Ty::Apply(ApplicationTy { ctor, parameters })
+    }
+    pub fn unit() -> Self {
+        Ty::apply(TypeCtor::Tuple { cardinality: 0 }, Substs::empty())
+    }
+
+    pub fn as_reference(&self) -> Option<(&Ty, Mutability)> {
+        match self {
+            Ty::Apply(ApplicationTy { ctor: TypeCtor::Ref(mutability), parameters }) => {
+                Some((parameters.as_single(), *mutability))
+            }
+            _ => None,
+        }
+    }
+
+    pub fn as_adt(&self) -> Option<(AdtId, &Substs)> {
+        match self {
+            Ty::Apply(ApplicationTy { ctor: TypeCtor::Adt(adt_def), parameters }) => {
+                Some((*adt_def, parameters))
+            }
+            _ => None,
+        }
+    }
+
+    pub fn as_tuple(&self) -> Option<&Substs> {
+        match self {
+            Ty::Apply(ApplicationTy { ctor: TypeCtor::Tuple { .. }, parameters }) => {
+                Some(parameters)
+            }
+            _ => None,
+        }
+    }
+
+    pub fn as_callable(&self) -> Option<(CallableDef, &Substs)> {
+        match self {
+            Ty::Apply(ApplicationTy { ctor: TypeCtor::FnDef(callable_def), parameters }) => {
+                Some((*callable_def, parameters))
+            }
+            _ => None,
+        }
+    }
+
+    fn builtin_deref(&self) -> Option<Ty> {
+        match self {
+            Ty::Apply(a_ty) => match a_ty.ctor {
+                TypeCtor::Ref(..) => Some(Ty::clone(a_ty.parameters.as_single())),
+                TypeCtor::RawPtr(..) => Some(Ty::clone(a_ty.parameters.as_single())),
+                _ => None,
+            },
+            _ => None,
+        }
+    }
+
+    fn callable_sig(&self, db: &impl HirDatabase) -> Option<FnSig> {
+        match self {
+            Ty::Apply(a_ty) => match a_ty.ctor {
+                TypeCtor::FnPtr { .. } => Some(FnSig::from_fn_ptr_substs(&a_ty.parameters)),
+                TypeCtor::FnDef(def) => {
+                    let sig = db.callable_item_signature(def);
+                    Some(sig.subst(&a_ty.parameters))
+                }
+                TypeCtor::Closure { .. } => {
+                    let sig_param = &a_ty.parameters[0];
+                    sig_param.callable_sig(db)
+                }
+                _ => None,
+            },
+            _ => None,
+        }
+    }
+
+    /// If this is a type with type parameters (an ADT or function), replaces
+    /// the `Substs` for these type parameters with the given ones. (So e.g. if
+    /// `self` is `Option<_>` and the substs contain `u32`, we'll have
+    /// `Option<u32>` afterwards.)
+    pub fn apply_substs(self, substs: Substs) -> Ty {
+        match self {
+            Ty::Apply(ApplicationTy { ctor, parameters: previous_substs }) => {
+                assert_eq!(previous_substs.len(), substs.len());
+                Ty::Apply(ApplicationTy { ctor, parameters: substs })
+            }
+            _ => self,
+        }
+    }
+
+    /// Returns the type parameters of this type if it has some (i.e. is an ADT
+    /// or function); so if `self` is `Option<u32>`, this returns the `u32`.
+    pub fn substs(&self) -> Option<Substs> {
+        match self {
+            Ty::Apply(ApplicationTy { parameters, .. }) => Some(parameters.clone()),
+            _ => None,
+        }
+    }
+
+    /// If this is an `impl Trait` or `dyn Trait`, returns that trait.
+    pub fn inherent_trait(&self) -> Option<TraitId> {
+        match self {
+            Ty::Dyn(predicates) | Ty::Opaque(predicates) => {
+                predicates.iter().find_map(|pred| match pred {
+                    GenericPredicate::Implemented(tr) => Some(tr.trait_),
+                    _ => None,
+                })
+            }
+            _ => None,
+        }
+    }
+}
+
+/// This allows walking structures that contain types to do something with those
+/// types, similar to Chalk's `Fold` trait.
+pub trait TypeWalk {
+    fn walk(&self, f: &mut impl FnMut(&Ty));
+    fn walk_mut(&mut self, f: &mut impl FnMut(&mut Ty)) {
+        self.walk_mut_binders(&mut |ty, _binders| f(ty), 0);
+    }
+    /// Walk the type, counting entered binders.
+    ///
+    /// `Ty::Bound` variables use DeBruijn indexing, which means that 0 refers
+    /// to the innermost binder, 1 to the next, etc.. So when we want to
+    /// substitute a certain bound variable, we can't just walk the whole type
+    /// and blindly replace each instance of a certain index; when we 'enter'
+    /// things that introduce new bound variables, we have to keep track of
+    /// that. Currently, the only thing that introduces bound variables on our
+    /// side are `Ty::Dyn` and `Ty::Opaque`, which each introduce a bound
+    /// variable for the self type.
+    fn walk_mut_binders(&mut self, f: &mut impl FnMut(&mut Ty, usize), binders: usize);
+
+    fn fold(mut self, f: &mut impl FnMut(Ty) -> Ty) -> Self
+    where
+        Self: Sized,
+    {
+        self.walk_mut(&mut |ty_mut| {
+            let ty = mem::replace(ty_mut, Ty::Unknown);
+            *ty_mut = f(ty);
+        });
+        self
+    }
+
+    /// Replaces type parameters in this type using the given `Substs`. (So e.g.
+    /// if `self` is `&[T]`, where type parameter T has index 0, and the
+    /// `Substs` contain `u32` at index 0, we'll have `&[u32]` afterwards.)
+    fn subst(self, substs: &Substs) -> Self
+    where
+        Self: Sized,
+    {
+        self.fold(&mut |ty| match ty {
+            Ty::Param { idx, name } => {
+                substs.get(idx as usize).cloned().unwrap_or(Ty::Param { idx, name })
+            }
+            ty => ty,
+        })
+    }
+
+    /// Substitutes `Ty::Bound` vars (as opposed to type parameters).
+    fn subst_bound_vars(mut self, substs: &Substs) -> Self
+    where
+        Self: Sized,
+    {
+        self.walk_mut_binders(
+            &mut |ty, binders| match ty {
+                &mut Ty::Bound(idx) => {
+                    if idx as usize >= binders && (idx as usize - binders) < substs.len() {
+                        *ty = substs.0[idx as usize - binders].clone();
+                    }
+                }
+                _ => {}
+            },
+            0,
+        );
+        self
+    }
+
+    /// Shifts up `Ty::Bound` vars by `n`.
+    fn shift_bound_vars(self, n: i32) -> Self
+    where
+        Self: Sized,
+    {
+        self.fold(&mut |ty| match ty {
+            Ty::Bound(idx) => {
+                assert!(idx as i32 >= -n);
+                Ty::Bound((idx as i32 + n) as u32)
+            }
+            ty => ty,
+        })
+    }
+}
+
+impl TypeWalk for Ty {
+    fn walk(&self, f: &mut impl FnMut(&Ty)) {
+        match self {
+            Ty::Apply(a_ty) => {
+                for t in a_ty.parameters.iter() {
+                    t.walk(f);
+                }
+            }
+            Ty::Projection(p_ty) => {
+                for t in p_ty.parameters.iter() {
+                    t.walk(f);
+                }
+            }
+            Ty::Dyn(predicates) | Ty::Opaque(predicates) => {
+                for p in predicates.iter() {
+                    p.walk(f);
+                }
+            }
+            Ty::Param { .. } | Ty::Bound(_) | Ty::Infer(_) | Ty::Unknown => {}
+        }
+        f(self);
+    }
+
+    fn walk_mut_binders(&mut self, f: &mut impl FnMut(&mut Ty, usize), binders: usize) {
+        match self {
+            Ty::Apply(a_ty) => {
+                a_ty.parameters.walk_mut_binders(f, binders);
+            }
+            Ty::Projection(p_ty) => {
+                p_ty.parameters.walk_mut_binders(f, binders);
+            }
+            Ty::Dyn(predicates) | Ty::Opaque(predicates) => {
+                for p in make_mut_slice(predicates) {
+                    p.walk_mut_binders(f, binders + 1);
+                }
+            }
+            Ty::Param { .. } | Ty::Bound(_) | Ty::Infer(_) | Ty::Unknown => {}
+        }
+        f(self, binders);
+    }
+}
+
+impl HirDisplay for &Ty {
+    fn hir_fmt(&self, f: &mut HirFormatter<impl HirDatabase>) -> fmt::Result {
+        HirDisplay::hir_fmt(*self, f)
+    }
+}
+
+impl HirDisplay for ApplicationTy {
+    fn hir_fmt(&self, f: &mut HirFormatter<impl HirDatabase>) -> fmt::Result {
+        if f.should_truncate() {
+            return write!(f, "…");
+        }
+
+        match self.ctor {
+            TypeCtor::Bool => write!(f, "bool")?,
+            TypeCtor::Char => write!(f, "char")?,
+            TypeCtor::Int(t) => write!(f, "{}", t)?,
+            TypeCtor::Float(t) => write!(f, "{}", t)?,
+            TypeCtor::Str => write!(f, "str")?,
+            TypeCtor::Slice => {
+                let t = self.parameters.as_single();
+                write!(f, "[{}]", t.display(f.db))?;
+            }
+            TypeCtor::Array => {
+                let t = self.parameters.as_single();
+                write!(f, "[{};_]", t.display(f.db))?;
+            }
+            TypeCtor::RawPtr(m) => {
+                let t = self.parameters.as_single();
+                write!(f, "*{}{}", m.as_keyword_for_ptr(), t.display(f.db))?;
+            }
+            TypeCtor::Ref(m) => {
+                let t = self.parameters.as_single();
+                write!(f, "&{}{}", m.as_keyword_for_ref(), t.display(f.db))?;
+            }
+            TypeCtor::Never => write!(f, "!")?,
+            TypeCtor::Tuple { .. } => {
+                let ts = &self.parameters;
+                if ts.len() == 1 {
+                    write!(f, "({},)", ts[0].display(f.db))?;
+                } else {
+                    write!(f, "(")?;
+                    f.write_joined(&*ts.0, ", ")?;
+                    write!(f, ")")?;
+                }
+            }
+            TypeCtor::FnPtr { .. } => {
+                let sig = FnSig::from_fn_ptr_substs(&self.parameters);
+                write!(f, "fn(")?;
+                f.write_joined(sig.params(), ", ")?;
+                write!(f, ") -> {}", sig.ret().display(f.db))?;
+            }
+            TypeCtor::FnDef(def) => {
+                let sig = f.db.callable_item_signature(def);
+                let name = match def {
+                    CallableDef::FunctionId(ff) => f.db.function_data(ff).name.clone(),
+                    CallableDef::StructId(s) => f.db.struct_data(s).name.clone(),
+                    CallableDef::EnumVariantId(e) => {
+                        let enum_data = f.db.enum_data(e.parent);
+                        enum_data.variants[e.local_id].name.clone()
+                    }
+                };
+                match def {
+                    CallableDef::FunctionId(_) => write!(f, "fn {}", name)?,
+                    CallableDef::StructId(_) | CallableDef::EnumVariantId(_) => {
+                        write!(f, "{}", name)?
+                    }
+                }
+                if self.parameters.len() > 0 {
+                    write!(f, "<")?;
+                    f.write_joined(&*self.parameters.0, ", ")?;
+                    write!(f, ">")?;
+                }
+                write!(f, "(")?;
+                f.write_joined(sig.params(), ", ")?;
+                write!(f, ") -> {}", sig.ret().display(f.db))?;
+            }
+            TypeCtor::Adt(def_id) => {
+                let name = match def_id {
+                    AdtId::StructId(it) => f.db.struct_data(it).name.clone(),
+                    AdtId::UnionId(it) => f.db.union_data(it).name.clone(),
+                    AdtId::EnumId(it) => f.db.enum_data(it).name.clone(),
+                };
+                write!(f, "{}", name)?;
+                if self.parameters.len() > 0 {
+                    write!(f, "<")?;
+                    f.write_joined(&*self.parameters.0, ", ")?;
+                    write!(f, ">")?;
+                }
+            }
+            TypeCtor::AssociatedType(type_alias) => {
+                let trait_ = match type_alias.lookup(f.db).container {
+                    ContainerId::TraitId(it) => it,
+                    _ => panic!("not an associated type"),
+                };
+                let trait_name = f.db.trait_data(trait_).name.clone();
+                let name = f.db.type_alias_data(type_alias).name.clone();
+                write!(f, "{}::{}", trait_name, name)?;
+                if self.parameters.len() > 0 {
+                    write!(f, "<")?;
+                    f.write_joined(&*self.parameters.0, ", ")?;
+                    write!(f, ">")?;
+                }
+            }
+            TypeCtor::Closure { .. } => {
+                let sig = self.parameters[0]
+                    .callable_sig(f.db)
+                    .expect("first closure parameter should contain signature");
+                write!(f, "|")?;
+                f.write_joined(sig.params(), ", ")?;
+                write!(f, "| -> {}", sig.ret().display(f.db))?;
+            }
+        }
+        Ok(())
+    }
+}
+
+impl HirDisplay for ProjectionTy {
+    fn hir_fmt(&self, f: &mut HirFormatter<impl HirDatabase>) -> fmt::Result {
+        if f.should_truncate() {
+            return write!(f, "…");
+        }
+
+        let trait_name = f.db.trait_data(self.trait_(f.db)).name.clone();
+        write!(f, "<{} as {}", self.parameters[0].display(f.db), trait_name,)?;
+        if self.parameters.len() > 1 {
+            write!(f, "<")?;
+            f.write_joined(&self.parameters[1..], ", ")?;
+            write!(f, ">")?;
+        }
+        write!(f, ">::{}", f.db.type_alias_data(self.associated_ty).name)?;
+        Ok(())
+    }
+}
+
+impl HirDisplay for Ty {
+    fn hir_fmt(&self, f: &mut HirFormatter<impl HirDatabase>) -> fmt::Result {
+        if f.should_truncate() {
+            return write!(f, "…");
+        }
+
+        match self {
+            Ty::Apply(a_ty) => a_ty.hir_fmt(f)?,
+            Ty::Projection(p_ty) => p_ty.hir_fmt(f)?,
+            Ty::Param { name, .. } => write!(f, "{}", name)?,
+            Ty::Bound(idx) => write!(f, "?{}", idx)?,
+            Ty::Dyn(predicates) | Ty::Opaque(predicates) => {
+                match self {
+                    Ty::Dyn(_) => write!(f, "dyn ")?,
+                    Ty::Opaque(_) => write!(f, "impl ")?,
+                    _ => unreachable!(),
+                };
+                // Note: This code is written to produce nice results (i.e.
+                // corresponding to surface Rust) for types that can occur in
+                // actual Rust. It will have weird results if the predicates
+                // aren't as expected (i.e. self types = $0, projection
+                // predicates for a certain trait come after the Implemented
+                // predicate for that trait).
+                let mut first = true;
+                let mut angle_open = false;
+                for p in predicates.iter() {
+                    match p {
+                        GenericPredicate::Implemented(trait_ref) => {
+                            if angle_open {
+                                write!(f, ">")?;
+                            }
+                            if !first {
+                                write!(f, " + ")?;
+                            }
+                            // We assume that the self type is $0 (i.e. the
+                            // existential) here, which is the only thing that's
+                            // possible in actual Rust, and hence don't print it
+                            write!(f, "{}", f.db.trait_data(trait_ref.trait_).name.clone())?;
+                            if trait_ref.substs.len() > 1 {
+                                write!(f, "<")?;
+                                f.write_joined(&trait_ref.substs[1..], ", ")?;
+                                // there might be assoc type bindings, so we leave the angle brackets open
+                                angle_open = true;
+                            }
+                        }
+                        GenericPredicate::Projection(projection_pred) => {
+                            // in types in actual Rust, these will always come
+                            // after the corresponding Implemented predicate
+                            if angle_open {
+                                write!(f, ", ")?;
+                            } else {
+                                write!(f, "<")?;
+                                angle_open = true;
+                            }
+                            let name =
+                                f.db.type_alias_data(projection_pred.projection_ty.associated_ty)
+                                    .name
+                                    .clone();
+                            write!(f, "{} = ", name)?;
+                            projection_pred.ty.hir_fmt(f)?;
+                        }
+                        GenericPredicate::Error => {
+                            if angle_open {
+                                // impl Trait<X, {error}>
+                                write!(f, ", ")?;
+                            } else if !first {
+                                // impl Trait + {error}
+                                write!(f, " + ")?;
+                            }
+                            p.hir_fmt(f)?;
+                        }
+                    }
+                    first = false;
+                }
+                if angle_open {
+                    write!(f, ">")?;
+                }
+            }
+            Ty::Unknown => write!(f, "{{unknown}}")?,
+            Ty::Infer(..) => write!(f, "_")?,
+        }
+        Ok(())
+    }
+}
+
+impl TraitRef {
+    fn hir_fmt_ext(&self, f: &mut HirFormatter<impl HirDatabase>, use_as: bool) -> fmt::Result {
+        if f.should_truncate() {
+            return write!(f, "…");
+        }
+
+        self.substs[0].hir_fmt(f)?;
+        if use_as {
+            write!(f, " as ")?;
+        } else {
+            write!(f, ": ")?;
+        }
+        write!(f, "{}", f.db.trait_data(self.trait_).name.clone())?;
+        if self.substs.len() > 1 {
+            write!(f, "<")?;
+            f.write_joined(&self.substs[1..], ", ")?;
+            write!(f, ">")?;
+        }
+        Ok(())
+    }
+}
+
+impl HirDisplay for TraitRef {
+    fn hir_fmt(&self, f: &mut HirFormatter<impl HirDatabase>) -> fmt::Result {
+        self.hir_fmt_ext(f, false)
+    }
+}
+
+impl HirDisplay for &GenericPredicate {
+    fn hir_fmt(&self, f: &mut HirFormatter<impl HirDatabase>) -> fmt::Result {
+        HirDisplay::hir_fmt(*self, f)
+    }
+}
+
+impl HirDisplay for GenericPredicate {
+    fn hir_fmt(&self, f: &mut HirFormatter<impl HirDatabase>) -> fmt::Result {
+        if f.should_truncate() {
+            return write!(f, "…");
+        }
+
+        match self {
+            GenericPredicate::Implemented(trait_ref) => trait_ref.hir_fmt(f)?,
+            GenericPredicate::Projection(projection_pred) => {
+                write!(f, "<")?;
+                projection_pred.projection_ty.trait_ref(f.db).hir_fmt_ext(f, true)?;
+                write!(
+                    f,
+                    ">::{} = {}",
+                    f.db.type_alias_data(projection_pred.projection_ty.associated_ty).name,
+                    projection_pred.ty.display(f.db)
+                )?;
+            }
+            GenericPredicate::Error => write!(f, "{{error}}")?,
+        }
+        Ok(())
+    }
+}
+
+impl HirDisplay for Obligation {
+    fn hir_fmt(&self, f: &mut HirFormatter<impl HirDatabase>) -> fmt::Result {
+        match self {
+            Obligation::Trait(tr) => write!(f, "Implements({})", tr.display(f.db)),
+            Obligation::Projection(proj) => write!(
+                f,
+                "Normalize({} => {})",
+                proj.projection_ty.display(f.db),
+                proj.ty.display(f.db)
+            ),
+        }
+    }
+}
diff --git a/crates/ra_hir_ty/src/lower.rs b/crates/ra_hir_ty/src/lower.rs
new file mode 100644
index 000000000..091c60f4f
--- /dev/null
+++ b/crates/ra_hir_ty/src/lower.rs
@@ -0,0 +1,759 @@
+//! Methods for lowering the HIR to types. There are two main cases here:
+//!
+//!  - Lowering a type reference like `&usize` or `Option<foo::bar::Baz>` to a
+//!    type: The entry point for this is `Ty::from_hir`.
+//!  - Building the type for an item: This happens through the `type_for_def` query.
+//!
+//! This usually involves resolving names, collecting generic arguments etc.
+use std::iter;
+use std::sync::Arc;
+
+use hir_def::{
+    builtin_type::BuiltinType,
+    generics::WherePredicate,
+    path::{GenericArg, Path, PathKind, PathSegment},
+    resolver::{HasResolver, Resolver, TypeNs},
+    type_ref::{TypeBound, TypeRef},
+    AdtId, AstItemDef, ConstId, EnumId, EnumVariantId, FunctionId, GenericDefId, HasModule, ImplId,
+    LocalStructFieldId, Lookup, StaticId, StructId, TraitId, TypeAliasId, UnionId, VariantId,
+};
+use ra_arena::map::ArenaMap;
+use ra_db::CrateId;
+
+use crate::{
+    db::HirDatabase,
+    primitive::{FloatTy, IntTy},
+    utils::{
+        all_super_traits, associated_type_by_name_including_super_traits, make_mut_slice,
+        variant_data,
+    },
+    FnSig, GenericPredicate, ImplTy, ProjectionPredicate, ProjectionTy, Substs, TraitEnvironment,
+    TraitRef, Ty, TypeCtor, TypeWalk,
+};
+
+impl Ty {
+    pub fn from_hir(db: &impl HirDatabase, resolver: &Resolver, type_ref: &TypeRef) -> Self {
+        match type_ref {
+            TypeRef::Never => Ty::simple(TypeCtor::Never),
+            TypeRef::Tuple(inner) => {
+                let inner_tys: Arc<[Ty]> =
+                    inner.iter().map(|tr| Ty::from_hir(db, resolver, tr)).collect();
+                Ty::apply(
+                    TypeCtor::Tuple { cardinality: inner_tys.len() as u16 },
+                    Substs(inner_tys),
+                )
+            }
+            TypeRef::Path(path) => Ty::from_hir_path(db, resolver, path),
+            TypeRef::RawPtr(inner, mutability) => {
+                let inner_ty = Ty::from_hir(db, resolver, inner);
+                Ty::apply_one(TypeCtor::RawPtr(*mutability), inner_ty)
+            }
+            TypeRef::Array(inner) => {
+                let inner_ty = Ty::from_hir(db, resolver, inner);
+                Ty::apply_one(TypeCtor::Array, inner_ty)
+            }
+            TypeRef::Slice(inner) => {
+                let inner_ty = Ty::from_hir(db, resolver, inner);
+                Ty::apply_one(TypeCtor::Slice, inner_ty)
+            }
+            TypeRef::Reference(inner, mutability) => {
+                let inner_ty = Ty::from_hir(db, resolver, inner);
+                Ty::apply_one(TypeCtor::Ref(*mutability), inner_ty)
+            }
+            TypeRef::Placeholder => Ty::Unknown,
+            TypeRef::Fn(params) => {
+                let sig = Substs(params.iter().map(|tr| Ty::from_hir(db, resolver, tr)).collect());
+                Ty::apply(TypeCtor::FnPtr { num_args: sig.len() as u16 - 1 }, sig)
+            }
+            TypeRef::DynTrait(bounds) => {
+                let self_ty = Ty::Bound(0);
+                let predicates = bounds
+                    .iter()
+                    .flat_map(|b| {
+                        GenericPredicate::from_type_bound(db, resolver, b, self_ty.clone())
+                    })
+                    .collect();
+                Ty::Dyn(predicates)
+            }
+            TypeRef::ImplTrait(bounds) => {
+                let self_ty = Ty::Bound(0);
+                let predicates = bounds
+                    .iter()
+                    .flat_map(|b| {
+                        GenericPredicate::from_type_bound(db, resolver, b, self_ty.clone())
+                    })
+                    .collect();
+                Ty::Opaque(predicates)
+            }
+            TypeRef::Error => Ty::Unknown,
+        }
+    }
+
+    /// This is only for `generic_predicates_for_param`, where we can't just
+    /// lower the self types of the predicates since that could lead to cycles.
+    /// So we just check here if the `type_ref` resolves to a generic param, and which.
+    fn from_hir_only_param(
+        db: &impl HirDatabase,
+        resolver: &Resolver,
+        type_ref: &TypeRef,
+    ) -> Option<u32> {
+        let path = match type_ref {
+            TypeRef::Path(path) => path,
+            _ => return None,
+        };
+        if let PathKind::Type(_) = &path.kind {
+            return None;
+        }
+        if path.segments.len() > 1 {
+            return None;
+        }
+        let resolution = match resolver.resolve_path_in_type_ns(db, path) {
+            Some((it, None)) => it,
+            _ => return None,
+        };
+        if let TypeNs::GenericParam(idx) = resolution {
+            Some(idx)
+        } else {
+            None
+        }
+    }
+
+    pub(crate) fn from_type_relative_path(
+        db: &impl HirDatabase,
+        resolver: &Resolver,
+        ty: Ty,
+        remaining_segments: &[PathSegment],
+    ) -> Ty {
+        if remaining_segments.len() == 1 {
+            // resolve unselected assoc types
+            let segment = &remaining_segments[0];
+            Ty::select_associated_type(db, resolver, ty, segment)
+        } else if remaining_segments.len() > 1 {
+            // FIXME report error (ambiguous associated type)
+            Ty::Unknown
+        } else {
+            ty
+        }
+    }
+
+    pub(crate) fn from_partly_resolved_hir_path(
+        db: &impl HirDatabase,
+        resolver: &Resolver,
+        resolution: TypeNs,
+        resolved_segment: &PathSegment,
+        remaining_segments: &[PathSegment],
+    ) -> Ty {
+        let ty = match resolution {
+            TypeNs::TraitId(trait_) => {
+                let trait_ref =
+                    TraitRef::from_resolved_path(db, resolver, trait_, resolved_segment, None);
+                return if remaining_segments.len() == 1 {
+                    let segment = &remaining_segments[0];
+                    let associated_ty = associated_type_by_name_including_super_traits(
+                        db,
+                        trait_ref.trait_,
+                        &segment.name,
+                    );
+                    match associated_ty {
+                        Some(associated_ty) => {
+                            // FIXME handle type parameters on the segment
+                            Ty::Projection(ProjectionTy {
+                                associated_ty,
+                                parameters: trait_ref.substs,
+                            })
+                        }
+                        None => {
+                            // FIXME: report error (associated type not found)
+                            Ty::Unknown
+                        }
+                    }
+                } else if remaining_segments.len() > 1 {
+                    // FIXME report error (ambiguous associated type)
+                    Ty::Unknown
+                } else {
+                    Ty::Dyn(Arc::new([GenericPredicate::Implemented(trait_ref)]))
+                };
+            }
+            TypeNs::GenericParam(idx) => {
+                // FIXME: maybe return name in resolution?
+                let name = resolved_segment.name.clone();
+                Ty::Param { idx, name }
+            }
+            TypeNs::SelfType(impl_id) => db.impl_ty(impl_id).self_type().clone(),
+            TypeNs::AdtSelfType(adt) => db.ty(adt.into()),
+
+            TypeNs::AdtId(it) => Ty::from_hir_path_inner(db, resolver, resolved_segment, it.into()),
+            TypeNs::BuiltinType(it) => {
+                Ty::from_hir_path_inner(db, resolver, resolved_segment, it.into())
+            }
+            TypeNs::TypeAliasId(it) => {
+                Ty::from_hir_path_inner(db, resolver, resolved_segment, it.into())
+            }
+            // FIXME: report error
+            TypeNs::EnumVariantId(_) => return Ty::Unknown,
+        };
+
+        Ty::from_type_relative_path(db, resolver, ty, remaining_segments)
+    }
+
+    pub(crate) fn from_hir_path(db: &impl HirDatabase, resolver: &Resolver, path: &Path) -> Ty {
+        // Resolve the path (in type namespace)
+        if let PathKind::Type(type_ref) = &path.kind {
+            let ty = Ty::from_hir(db, resolver, &type_ref);
+            let remaining_segments = &path.segments[..];
+            return Ty::from_type_relative_path(db, resolver, ty, remaining_segments);
+        }
+        let (resolution, remaining_index) = match resolver.resolve_path_in_type_ns(db, path) {
+            Some(it) => it,
+            None => return Ty::Unknown,
+        };
+        let (resolved_segment, remaining_segments) = match remaining_index {
+            None => (
+                path.segments.last().expect("resolved path has at least one element"),
+                &[] as &[PathSegment],
+            ),
+            Some(i) => (&path.segments[i - 1], &path.segments[i..]),
+        };
+        Ty::from_partly_resolved_hir_path(
+            db,
+            resolver,
+            resolution,
+            resolved_segment,
+            remaining_segments,
+        )
+    }
+
+    fn select_associated_type(
+        db: &impl HirDatabase,
+        resolver: &Resolver,
+        self_ty: Ty,
+        segment: &PathSegment,
+    ) -> Ty {
+        let param_idx = match self_ty {
+            Ty::Param { idx, .. } => idx,
+            _ => return Ty::Unknown, // Error: Ambiguous associated type
+        };
+        let def = match resolver.generic_def() {
+            Some(def) => def,
+            None => return Ty::Unknown, // this can't actually happen
+        };
+        let predicates = db.generic_predicates_for_param(def.into(), param_idx);
+        let traits_from_env = predicates.iter().filter_map(|pred| match pred {
+            GenericPredicate::Implemented(tr) if tr.self_ty() == &self_ty => Some(tr.trait_),
+            _ => None,
+        });
+        let traits = traits_from_env.flat_map(|t| all_super_traits(db, t));
+        for t in traits {
+            if let Some(associated_ty) = db.trait_data(t).associated_type_by_name(&segment.name) {
+                let substs =
+                    Substs::build_for_def(db, t).push(self_ty.clone()).fill_with_unknown().build();
+                // FIXME handle type parameters on the segment
+                return Ty::Projection(ProjectionTy { associated_ty, parameters: substs });
+            }
+        }
+        Ty::Unknown
+    }
+
+    fn from_hir_path_inner(
+        db: &impl HirDatabase,
+        resolver: &Resolver,
+        segment: &PathSegment,
+        typable: TyDefId,
+    ) -> Ty {
+        let generic_def = match typable {
+            TyDefId::BuiltinType(_) => None,
+            TyDefId::AdtId(it) => Some(it.into()),
+            TyDefId::TypeAliasId(it) => Some(it.into()),
+        };
+        let substs = substs_from_path_segment(db, resolver, segment, generic_def, false);
+        db.ty(typable).subst(&substs)
+    }
+
+    /// Collect generic arguments from a path into a `Substs`. See also
+    /// `create_substs_for_ast_path` and `def_to_ty` in rustc.
+    pub(super) fn substs_from_path(
+        db: &impl HirDatabase,
+        resolver: &Resolver,
+        path: &Path,
+        // Note that we don't call `db.value_type(resolved)` here,
+        // `ValueTyDefId` is just a convenient way to pass generics and
+        // special-case enum variants
+        resolved: ValueTyDefId,
+    ) -> Substs {
+        let last = path.segments.last().expect("path should have at least one segment");
+        let (segment, generic_def) = match resolved {
+            ValueTyDefId::FunctionId(it) => (last, Some(it.into())),
+            ValueTyDefId::StructId(it) => (last, Some(it.into())),
+            ValueTyDefId::ConstId(it) => (last, Some(it.into())),
+            ValueTyDefId::StaticId(_) => (last, None),
+            ValueTyDefId::EnumVariantId(var) => {
+                // the generic args for an enum variant may be either specified
+                // on the segment referring to the enum, or on the segment
+                // referring to the variant. So `Option::<T>::None` and
+                // `Option::None::<T>` are both allowed (though the former is
+                // preferred). See also `def_ids_for_path_segments` in rustc.
+                let len = path.segments.len();
+                let segment = if len >= 2 && path.segments[len - 2].args_and_bindings.is_some() {
+                    // Option::<T>::None
+                    &path.segments[len - 2]
+                } else {
+                    // Option::None::<T>
+                    last
+                };
+                (segment, Some(var.parent.into()))
+            }
+        };
+        substs_from_path_segment(db, resolver, segment, generic_def, false)
+    }
+}
+
+pub(super) fn substs_from_path_segment(
+    db: &impl HirDatabase,
+    resolver: &Resolver,
+    segment: &PathSegment,
+    def_generic: Option<GenericDefId>,
+    add_self_param: bool,
+) -> Substs {
+    let mut substs = Vec::new();
+    let def_generics = def_generic.map(|def| db.generic_params(def.into()));
+
+    let (parent_param_count, param_count) =
+        def_generics.map_or((0, 0), |g| (g.count_parent_params(), g.params.len()));
+    substs.extend(iter::repeat(Ty::Unknown).take(parent_param_count));
+    if add_self_param {
+        // FIXME this add_self_param argument is kind of a hack: Traits have the
+        // Self type as an implicit first type parameter, but it can't be
+        // actually provided in the type arguments
+        // (well, actually sometimes it can, in the form of type-relative paths: `<Foo as Default>::default()`)
+        substs.push(Ty::Unknown);
+    }
+    if let Some(generic_args) = &segment.args_and_bindings {
+        // if args are provided, it should be all of them, but we can't rely on that
+        let self_param_correction = if add_self_param { 1 } else { 0 };
+        let param_count = param_count - self_param_correction;
+        for arg in generic_args.args.iter().take(param_count) {
+            match arg {
+                GenericArg::Type(type_ref) => {
+                    let ty = Ty::from_hir(db, resolver, type_ref);
+                    substs.push(ty);
+                }
+            }
+        }
+    }
+    // add placeholders for args that were not provided
+    let supplied_params = substs.len();
+    for _ in supplied_params..parent_param_count + param_count {
+        substs.push(Ty::Unknown);
+    }
+    assert_eq!(substs.len(), parent_param_count + param_count);
+
+    // handle defaults
+    if let Some(def_generic) = def_generic {
+        let default_substs = db.generic_defaults(def_generic.into());
+        assert_eq!(substs.len(), default_substs.len());
+
+        for (i, default_ty) in default_substs.iter().enumerate() {
+            if substs[i] == Ty::Unknown {
+                substs[i] = default_ty.clone();
+            }
+        }
+    }
+
+    Substs(substs.into())
+}
+
+impl TraitRef {
+    fn from_path(
+        db: &impl HirDatabase,
+        resolver: &Resolver,
+        path: &Path,
+        explicit_self_ty: Option<Ty>,
+    ) -> Option<Self> {
+        let resolved = match resolver.resolve_path_in_type_ns_fully(db, &path)? {
+            TypeNs::TraitId(tr) => tr,
+            _ => return None,
+        };
+        let segment = path.segments.last().expect("path should have at least one segment");
+        Some(TraitRef::from_resolved_path(db, resolver, resolved.into(), segment, explicit_self_ty))
+    }
+
+    pub(crate) fn from_resolved_path(
+        db: &impl HirDatabase,
+        resolver: &Resolver,
+        resolved: TraitId,
+        segment: &PathSegment,
+        explicit_self_ty: Option<Ty>,
+    ) -> Self {
+        let mut substs = TraitRef::substs_from_path(db, resolver, segment, resolved);
+        if let Some(self_ty) = explicit_self_ty {
+            make_mut_slice(&mut substs.0)[0] = self_ty;
+        }
+        TraitRef { trait_: resolved, substs }
+    }
+
+    fn from_hir(
+        db: &impl HirDatabase,
+        resolver: &Resolver,
+        type_ref: &TypeRef,
+        explicit_self_ty: Option<Ty>,
+    ) -> Option<Self> {
+        let path = match type_ref {
+            TypeRef::Path(path) => path,
+            _ => return None,
+        };
+        TraitRef::from_path(db, resolver, path, explicit_self_ty)
+    }
+
+    fn substs_from_path(
+        db: &impl HirDatabase,
+        resolver: &Resolver,
+        segment: &PathSegment,
+        resolved: TraitId,
+    ) -> Substs {
+        let has_self_param =
+            segment.args_and_bindings.as_ref().map(|a| a.has_self_type).unwrap_or(false);
+        substs_from_path_segment(db, resolver, segment, Some(resolved.into()), !has_self_param)
+    }
+
+    pub(crate) fn from_type_bound(
+        db: &impl HirDatabase,
+        resolver: &Resolver,
+        bound: &TypeBound,
+        self_ty: Ty,
+    ) -> Option<TraitRef> {
+        match bound {
+            TypeBound::Path(path) => TraitRef::from_path(db, resolver, path, Some(self_ty)),
+            TypeBound::Error => None,
+        }
+    }
+}
+
+impl GenericPredicate {
+    pub(crate) fn from_where_predicate<'a>(
+        db: &'a impl HirDatabase,
+        resolver: &'a Resolver,
+        where_predicate: &'a WherePredicate,
+    ) -> impl Iterator<Item = GenericPredicate> + 'a {
+        let self_ty = Ty::from_hir(db, resolver, &where_predicate.type_ref);
+        GenericPredicate::from_type_bound(db, resolver, &where_predicate.bound, self_ty)
+    }
+
+    pub(crate) fn from_type_bound<'a>(
+        db: &'a impl HirDatabase,
+        resolver: &'a Resolver,
+        bound: &'a TypeBound,
+        self_ty: Ty,
+    ) -> impl Iterator<Item = GenericPredicate> + 'a {
+        let trait_ref = TraitRef::from_type_bound(db, &resolver, bound, self_ty);
+        iter::once(trait_ref.clone().map_or(GenericPredicate::Error, GenericPredicate::Implemented))
+            .chain(
+                trait_ref.into_iter().flat_map(move |tr| {
+                    assoc_type_bindings_from_type_bound(db, resolver, bound, tr)
+                }),
+            )
+    }
+}
+
+fn assoc_type_bindings_from_type_bound<'a>(
+    db: &'a impl HirDatabase,
+    resolver: &'a Resolver,
+    bound: &'a TypeBound,
+    trait_ref: TraitRef,
+) -> impl Iterator<Item = GenericPredicate> + 'a {
+    let last_segment = match bound {
+        TypeBound::Path(path) => path.segments.last(),
+        TypeBound::Error => None,
+    };
+    last_segment
+        .into_iter()
+        .flat_map(|segment| segment.args_and_bindings.iter())
+        .flat_map(|args_and_bindings| args_and_bindings.bindings.iter())
+        .map(move |(name, type_ref)| {
+            let associated_ty =
+                associated_type_by_name_including_super_traits(db, trait_ref.trait_, &name);
+            let associated_ty = match associated_ty {
+                None => return GenericPredicate::Error,
+                Some(t) => t,
+            };
+            let projection_ty =
+                ProjectionTy { associated_ty, parameters: trait_ref.substs.clone() };
+            let ty = Ty::from_hir(db, resolver, type_ref);
+            let projection_predicate = ProjectionPredicate { projection_ty, ty };
+            GenericPredicate::Projection(projection_predicate)
+        })
+}
+
+/// Build the signature of a callable item (function, struct or enum variant).
+pub fn callable_item_sig(db: &impl HirDatabase, def: CallableDef) -> FnSig {
+    match def {
+        CallableDef::FunctionId(f) => fn_sig_for_fn(db, f),
+        CallableDef::StructId(s) => fn_sig_for_struct_constructor(db, s),
+        CallableDef::EnumVariantId(e) => fn_sig_for_enum_variant_constructor(db, e),
+    }
+}
+
+/// Build the type of all specific fields of a struct or enum variant.
+pub(crate) fn field_types_query(
+    db: &impl HirDatabase,
+    variant_id: VariantId,
+) -> Arc<ArenaMap<LocalStructFieldId, Ty>> {
+    let var_data = variant_data(db, variant_id);
+    let resolver = match variant_id {
+        VariantId::StructId(it) => it.resolver(db),
+        VariantId::UnionId(it) => it.resolver(db),
+        VariantId::EnumVariantId(it) => it.parent.resolver(db),
+    };
+    let mut res = ArenaMap::default();
+    for (field_id, field_data) in var_data.fields().iter() {
+        res.insert(field_id, Ty::from_hir(db, &resolver, &field_data.type_ref))
+    }
+    Arc::new(res)
+}
+
+/// This query exists only to be used when resolving short-hand associated types
+/// like `T::Item`.
+///
+/// See the analogous query in rustc and its comment:
+/// https://github.com/rust-lang/rust/blob/9150f844e2624eb013ec78ca08c1d416e6644026/src/librustc_typeck/astconv.rs#L46
+/// This is a query mostly to handle cycles somewhat gracefully; e.g. the
+/// following bounds are disallowed: `T: Foo<U::Item>, U: Foo<T::Item>`, but
+/// these are fine: `T: Foo<U::Item>, U: Foo<()>`.
+pub(crate) fn generic_predicates_for_param_query(
+    db: &impl HirDatabase,
+    def: GenericDefId,
+    param_idx: u32,
+) -> Arc<[GenericPredicate]> {
+    let resolver = def.resolver(db);
+    resolver
+        .where_predicates_in_scope()
+        // we have to filter out all other predicates *first*, before attempting to lower them
+        .filter(|pred| Ty::from_hir_only_param(db, &resolver, &pred.type_ref) == Some(param_idx))
+        .flat_map(|pred| GenericPredicate::from_where_predicate(db, &resolver, pred))
+        .collect()
+}
+
+impl TraitEnvironment {
+    pub fn lower(db: &impl HirDatabase, resolver: &Resolver) -> Arc<TraitEnvironment> {
+        let predicates = resolver
+            .where_predicates_in_scope()
+            .flat_map(|pred| GenericPredicate::from_where_predicate(db, &resolver, pred))
+            .collect::<Vec<_>>();
+
+        Arc::new(TraitEnvironment { predicates })
+    }
+}
+
+/// Resolve the where clause(s) of an item with generics.
+pub(crate) fn generic_predicates_query(
+    db: &impl HirDatabase,
+    def: GenericDefId,
+) -> Arc<[GenericPredicate]> {
+    let resolver = def.resolver(db);
+    resolver
+        .where_predicates_in_scope()
+        .flat_map(|pred| GenericPredicate::from_where_predicate(db, &resolver, pred))
+        .collect()
+}
+
+/// Resolve the default type params from generics
+pub(crate) fn generic_defaults_query(db: &impl HirDatabase, def: GenericDefId) -> Substs {
+    let resolver = def.resolver(db);
+    let generic_params = db.generic_params(def.into());
+
+    let defaults = generic_params
+        .params_including_parent()
+        .into_iter()
+        .map(|p| p.default.as_ref().map_or(Ty::Unknown, |t| Ty::from_hir(db, &resolver, t)))
+        .collect();
+
+    Substs(defaults)
+}
+
+fn fn_sig_for_fn(db: &impl HirDatabase, def: FunctionId) -> FnSig {
+    let data = db.function_data(def);
+    let resolver = def.resolver(db);
+    let params = data.params.iter().map(|tr| Ty::from_hir(db, &resolver, tr)).collect::<Vec<_>>();
+    let ret = Ty::from_hir(db, &resolver, &data.ret_type);
+    FnSig::from_params_and_return(params, ret)
+}
+
+/// Build the declared type of a function. This should not need to look at the
+/// function body.
+fn type_for_fn(db: &impl HirDatabase, def: FunctionId) -> Ty {
+    let generics = db.generic_params(def.into());
+    let substs = Substs::identity(&generics);
+    Ty::apply(TypeCtor::FnDef(def.into()), substs)
+}
+
+/// Build the declared type of a const.
+fn type_for_const(db: &impl HirDatabase, def: ConstId) -> Ty {
+    let data = db.const_data(def);
+    let resolver = def.resolver(db);
+
+    Ty::from_hir(db, &resolver, &data.type_ref)
+}
+
+/// Build the declared type of a static.
+fn type_for_static(db: &impl HirDatabase, def: StaticId) -> Ty {
+    let data = db.static_data(def);
+    let resolver = def.resolver(db);
+
+    Ty::from_hir(db, &resolver, &data.type_ref)
+}
+
+/// Build the declared type of a static.
+fn type_for_builtin(def: BuiltinType) -> Ty {
+    Ty::simple(match def {
+        BuiltinType::Char => TypeCtor::Char,
+        BuiltinType::Bool => TypeCtor::Bool,
+        BuiltinType::Str => TypeCtor::Str,
+        BuiltinType::Int(t) => TypeCtor::Int(IntTy::from(t).into()),
+        BuiltinType::Float(t) => TypeCtor::Float(FloatTy::from(t).into()),
+    })
+}
+
+fn fn_sig_for_struct_constructor(db: &impl HirDatabase, def: StructId) -> FnSig {
+    let struct_data = db.struct_data(def.into());
+    let fields = struct_data.variant_data.fields();
+    let resolver = def.resolver(db);
+    let params = fields
+        .iter()
+        .map(|(_, field)| Ty::from_hir(db, &resolver, &field.type_ref))
+        .collect::<Vec<_>>();
+    let ret = type_for_adt(db, def.into());
+    FnSig::from_params_and_return(params, ret)
+}
+
+/// Build the type of a tuple struct constructor.
+fn type_for_struct_constructor(db: &impl HirDatabase, def: StructId) -> Ty {
+    let struct_data = db.struct_data(def.into());
+    if struct_data.variant_data.is_unit() {
+        return type_for_adt(db, def.into()); // Unit struct
+    }
+    let generics = db.generic_params(def.into());
+    let substs = Substs::identity(&generics);
+    Ty::apply(TypeCtor::FnDef(def.into()), substs)
+}
+
+fn fn_sig_for_enum_variant_constructor(db: &impl HirDatabase, def: EnumVariantId) -> FnSig {
+    let enum_data = db.enum_data(def.parent);
+    let var_data = &enum_data.variants[def.local_id];
+    let fields = var_data.variant_data.fields();
+    let resolver = def.parent.resolver(db);
+    let params = fields
+        .iter()
+        .map(|(_, field)| Ty::from_hir(db, &resolver, &field.type_ref))
+        .collect::<Vec<_>>();
+    let generics = db.generic_params(def.parent.into());
+    let substs = Substs::identity(&generics);
+    let ret = type_for_adt(db, def.parent.into()).subst(&substs);
+    FnSig::from_params_and_return(params, ret)
+}
+
+/// Build the type of a tuple enum variant constructor.
+fn type_for_enum_variant_constructor(db: &impl HirDatabase, def: EnumVariantId) -> Ty {
+    let enum_data = db.enum_data(def.parent);
+    let var_data = &enum_data.variants[def.local_id].variant_data;
+    if var_data.is_unit() {
+        return type_for_adt(db, def.parent.into()); // Unit variant
+    }
+    let generics = db.generic_params(def.parent.into());
+    let substs = Substs::identity(&generics);
+    Ty::apply(TypeCtor::FnDef(EnumVariantId::from(def).into()), substs)
+}
+
+fn type_for_adt(db: &impl HirDatabase, adt: AdtId) -> Ty {
+    let generics = db.generic_params(adt.into());
+    Ty::apply(TypeCtor::Adt(adt), Substs::identity(&generics))
+}
+
+fn type_for_type_alias(db: &impl HirDatabase, t: TypeAliasId) -> Ty {
+    let generics = db.generic_params(t.into());
+    let resolver = t.resolver(db);
+    let type_ref = &db.type_alias_data(t).type_ref;
+    let substs = Substs::identity(&generics);
+    let inner = Ty::from_hir(db, &resolver, type_ref.as_ref().unwrap_or(&TypeRef::Error));
+    inner.subst(&substs)
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+pub enum CallableDef {
+    FunctionId(FunctionId),
+    StructId(StructId),
+    EnumVariantId(EnumVariantId),
+}
+impl_froms!(CallableDef: FunctionId, StructId, EnumVariantId);
+
+impl CallableDef {
+    pub fn krate(self, db: &impl HirDatabase) -> CrateId {
+        match self {
+            CallableDef::FunctionId(f) => f.lookup(db).module(db).krate,
+            CallableDef::StructId(s) => s.module(db).krate,
+            CallableDef::EnumVariantId(e) => e.parent.module(db).krate,
+        }
+    }
+}
+
+impl From<CallableDef> for GenericDefId {
+    fn from(def: CallableDef) -> GenericDefId {
+        match def {
+            CallableDef::FunctionId(f) => f.into(),
+            CallableDef::StructId(s) => s.into(),
+            CallableDef::EnumVariantId(e) => e.into(),
+        }
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub enum TyDefId {
+    BuiltinType(BuiltinType),
+    AdtId(AdtId),
+    TypeAliasId(TypeAliasId),
+}
+impl_froms!(TyDefId: BuiltinType, AdtId(StructId, EnumId, UnionId), TypeAliasId);
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub enum ValueTyDefId {
+    FunctionId(FunctionId),
+    StructId(StructId),
+    EnumVariantId(EnumVariantId),
+    ConstId(ConstId),
+    StaticId(StaticId),
+}
+impl_froms!(ValueTyDefId: FunctionId, StructId, EnumVariantId, ConstId, StaticId);
+
+/// Build the declared type of an item. This depends on the namespace; e.g. for
+/// `struct Foo(usize)`, we have two types: The type of the struct itself, and
+/// the constructor function `(usize) -> Foo` which lives in the values
+/// namespace.
+pub(crate) fn ty_query(db: &impl HirDatabase, def: TyDefId) -> Ty {
+    match def {
+        TyDefId::BuiltinType(it) => type_for_builtin(it),
+        TyDefId::AdtId(it) => type_for_adt(db, it),
+        TyDefId::TypeAliasId(it) => type_for_type_alias(db, it),
+    }
+}
+pub(crate) fn value_ty_query(db: &impl HirDatabase, def: ValueTyDefId) -> Ty {
+    match def {
+        ValueTyDefId::FunctionId(it) => type_for_fn(db, it),
+        ValueTyDefId::StructId(it) => type_for_struct_constructor(db, it),
+        ValueTyDefId::EnumVariantId(it) => type_for_enum_variant_constructor(db, it),
+        ValueTyDefId::ConstId(it) => type_for_const(db, it),
+        ValueTyDefId::StaticId(it) => type_for_static(db, it),
+    }
+}
+
+pub(crate) fn impl_ty_query(db: &impl HirDatabase, impl_id: ImplId) -> ImplTy {
+    let impl_data = db.impl_data(impl_id);
+    let resolver = impl_id.resolver(db);
+    let self_ty = Ty::from_hir(db, &resolver, &impl_data.target_type);
+    match impl_data.target_trait.as_ref() {
+        Some(trait_ref) => {
+            match TraitRef::from_hir(db, &resolver, trait_ref, Some(self_ty.clone())) {
+                Some(it) => ImplTy::TraitRef(it),
+                None => ImplTy::Inherent(self_ty),
+            }
+        }
+        None => ImplTy::Inherent(self_ty),
+    }
+}
diff --git a/crates/ra_hir_ty/src/marks.rs b/crates/ra_hir_ty/src/marks.rs
new file mode 100644
index 000000000..0f754eb9c
--- /dev/null
+++ b/crates/ra_hir_ty/src/marks.rs
@@ -0,0 +1,9 @@
+//! See test_utils/src/marks.rs
+
+test_utils::marks!(
+    type_var_cycles_resolve_completely
+    type_var_cycles_resolve_as_possible
+    type_var_resolves_to_int_var
+    match_ergonomics_ref
+    coerce_merge_fail_fallback
+);
diff --git a/crates/ra_hir_ty/src/method_resolution.rs b/crates/ra_hir_ty/src/method_resolution.rs
new file mode 100644
index 000000000..ee1936b0e
--- /dev/null
+++ b/crates/ra_hir_ty/src/method_resolution.rs
@@ -0,0 +1,353 @@
+//! This module is concerned with finding methods that a given type provides.
+//! For details about how this works in rustc, see the method lookup page in the
+//! [rustc guide](https://rust-lang.github.io/rustc-guide/method-lookup.html)
+//! and the corresponding code mostly in librustc_typeck/check/method/probe.rs.
+use std::sync::Arc;
+
+use arrayvec::ArrayVec;
+use hir_def::{
+    lang_item::LangItemTarget, resolver::Resolver, type_ref::Mutability, AssocItemId, AstItemDef,
+    FunctionId, HasModule, ImplId, TraitId,
+};
+use hir_expand::name::Name;
+use ra_db::CrateId;
+use ra_prof::profile;
+use rustc_hash::FxHashMap;
+
+use crate::{
+    autoderef,
+    db::HirDatabase,
+    primitive::{FloatBitness, Uncertain},
+    utils::all_super_traits,
+    Canonical, ImplTy, InEnvironment, TraitEnvironment, TraitRef, Ty, TypeCtor,
+};
+
+/// This is used as a key for indexing impls.
+#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
+pub enum TyFingerprint {
+    Apply(TypeCtor),
+}
+
+impl TyFingerprint {
+    /// Creates a TyFingerprint for looking up an impl. Only certain types can
+    /// have impls: if we have some `struct S`, we can have an `impl S`, but not
+    /// `impl &S`. Hence, this will return `None` for reference types and such.
+    fn for_impl(ty: &Ty) -> Option<TyFingerprint> {
+        match ty {
+            Ty::Apply(a_ty) => Some(TyFingerprint::Apply(a_ty.ctor)),
+            _ => None,
+        }
+    }
+}
+
+#[derive(Debug, PartialEq, Eq)]
+pub struct CrateImplBlocks {
+    impls: FxHashMap<TyFingerprint, Vec<ImplId>>,
+    impls_by_trait: FxHashMap<TraitId, Vec<ImplId>>,
+}
+
+impl CrateImplBlocks {
+    pub(crate) fn impls_in_crate_query(
+        db: &impl HirDatabase,
+        krate: CrateId,
+    ) -> Arc<CrateImplBlocks> {
+        let _p = profile("impls_in_crate_query");
+        let mut res =
+            CrateImplBlocks { impls: FxHashMap::default(), impls_by_trait: FxHashMap::default() };
+
+        let crate_def_map = db.crate_def_map(krate);
+        for (_module_id, module_data) in crate_def_map.modules.iter() {
+            for &impl_id in module_data.impls.iter() {
+                match db.impl_ty(impl_id) {
+                    ImplTy::TraitRef(tr) => {
+                        res.impls_by_trait.entry(tr.trait_).or_default().push(impl_id);
+                    }
+                    ImplTy::Inherent(self_ty) => {
+                        if let Some(self_ty_fp) = TyFingerprint::for_impl(&self_ty) {
+                            res.impls.entry(self_ty_fp).or_default().push(impl_id);
+                        }
+                    }
+                }
+            }
+        }
+
+        Arc::new(res)
+    }
+    pub fn lookup_impl_blocks(&self, ty: &Ty) -> impl Iterator<Item = ImplId> + '_ {
+        let fingerprint = TyFingerprint::for_impl(ty);
+        fingerprint.and_then(|f| self.impls.get(&f)).into_iter().flatten().copied()
+    }
+
+    pub fn lookup_impl_blocks_for_trait(&self, tr: TraitId) -> impl Iterator<Item = ImplId> + '_ {
+        self.impls_by_trait.get(&tr).into_iter().flatten().copied()
+    }
+
+    pub fn all_impls<'a>(&'a self) -> impl Iterator<Item = ImplId> + 'a {
+        self.impls.values().chain(self.impls_by_trait.values()).flatten().copied()
+    }
+}
+
+impl Ty {
+    pub fn def_crates(
+        &self,
+        db: &impl HirDatabase,
+        cur_crate: CrateId,
+    ) -> Option<ArrayVec<[CrateId; 2]>> {
+        // Types like slice can have inherent impls in several crates, (core and alloc).
+        // The corresponding impls are marked with lang items, so we can use them to find the required crates.
+        macro_rules! lang_item_crate {
+        ($($name:expr),+ $(,)?) => {{
+            let mut v = ArrayVec::<[LangItemTarget; 2]>::new();
+            $(
+                v.extend(db.lang_item(cur_crate, $name.into()));
+            )+
+            v
+        }};
+    }
+
+        let lang_item_targets = match self {
+            Ty::Apply(a_ty) => match a_ty.ctor {
+                TypeCtor::Adt(def_id) => {
+                    return Some(std::iter::once(def_id.module(db).krate).collect())
+                }
+                TypeCtor::Bool => lang_item_crate!("bool"),
+                TypeCtor::Char => lang_item_crate!("char"),
+                TypeCtor::Float(Uncertain::Known(f)) => match f.bitness {
+                    // There are two lang items: one in libcore (fXX) and one in libstd (fXX_runtime)
+                    FloatBitness::X32 => lang_item_crate!("f32", "f32_runtime"),
+                    FloatBitness::X64 => lang_item_crate!("f64", "f64_runtime"),
+                },
+                TypeCtor::Int(Uncertain::Known(i)) => lang_item_crate!(i.ty_to_string()),
+                TypeCtor::Str => lang_item_crate!("str_alloc", "str"),
+                TypeCtor::Slice => lang_item_crate!("slice_alloc", "slice"),
+                TypeCtor::RawPtr(Mutability::Shared) => lang_item_crate!("const_ptr"),
+                TypeCtor::RawPtr(Mutability::Mut) => lang_item_crate!("mut_ptr"),
+                _ => return None,
+            },
+            _ => return None,
+        };
+        let res = lang_item_targets
+            .into_iter()
+            .filter_map(|it| match it {
+                LangItemTarget::ImplBlockId(it) => Some(it),
+                _ => None,
+            })
+            .map(|it| it.module(db).krate)
+            .collect();
+        Some(res)
+    }
+}
+/// Look up the method with the given name, returning the actual autoderefed
+/// receiver type (but without autoref applied yet).
+pub(crate) fn lookup_method(
+    ty: &Canonical<Ty>,
+    db: &impl HirDatabase,
+    name: &Name,
+    resolver: &Resolver,
+) -> Option<(Ty, FunctionId)> {
+    iterate_method_candidates(ty, db, resolver, Some(name), LookupMode::MethodCall, |ty, f| match f
+    {
+        AssocItemId::FunctionId(f) => Some((ty.clone(), f)),
+        _ => None,
+    })
+}
+
+/// Whether we're looking up a dotted method call (like `v.len()`) or a path
+/// (like `Vec::new`).
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
+pub enum LookupMode {
+    /// Looking up a method call like `v.len()`: We only consider candidates
+    /// that have a `self` parameter, and do autoderef.
+    MethodCall,
+    /// Looking up a path like `Vec::new` or `Vec::default`: We consider all
+    /// candidates including associated constants, but don't do autoderef.
+    Path,
+}
+
+// This would be nicer if it just returned an iterator, but that runs into
+// lifetime problems, because we need to borrow temp `CrateImplBlocks`.
+// FIXME add a context type here?
+pub fn iterate_method_candidates<T>(
+    ty: &Canonical<Ty>,
+    db: &impl HirDatabase,
+    resolver: &Resolver,
+    name: Option<&Name>,
+    mode: LookupMode,
+    mut callback: impl FnMut(&Ty, AssocItemId) -> Option<T>,
+) -> Option<T> {
+    let krate = resolver.krate()?;
+    match mode {
+        LookupMode::MethodCall => {
+            // For method calls, rust first does any number of autoderef, and then one
+            // autoref (i.e. when the method takes &self or &mut self). We just ignore
+            // the autoref currently -- when we find a method matching the given name,
+            // we assume it fits.
+
+            // Also note that when we've got a receiver like &S, even if the method we
+            // find in the end takes &self, we still do the autoderef step (just as
+            // rustc does an autoderef and then autoref again).
+            let environment = TraitEnvironment::lower(db, resolver);
+            let ty = InEnvironment { value: ty.clone(), environment };
+            for derefed_ty in autoderef::autoderef(db, resolver.krate(), ty) {
+                if let Some(result) =
+                    iterate_inherent_methods(&derefed_ty, db, name, mode, krate, &mut callback)
+                {
+                    return Some(result);
+                }
+                if let Some(result) = iterate_trait_method_candidates(
+                    &derefed_ty,
+                    db,
+                    resolver,
+                    name,
+                    mode,
+                    &mut callback,
+                ) {
+                    return Some(result);
+                }
+            }
+        }
+        LookupMode::Path => {
+            // No autoderef for path lookups
+            if let Some(result) =
+                iterate_inherent_methods(&ty, db, name, mode, krate.into(), &mut callback)
+            {
+                return Some(result);
+            }
+            if let Some(result) =
+                iterate_trait_method_candidates(&ty, db, resolver, name, mode, &mut callback)
+            {
+                return Some(result);
+            }
+        }
+    }
+    None
+}
+
+fn iterate_trait_method_candidates<T>(
+    ty: &Canonical<Ty>,
+    db: &impl HirDatabase,
+    resolver: &Resolver,
+    name: Option<&Name>,
+    mode: LookupMode,
+    mut callback: impl FnMut(&Ty, AssocItemId) -> Option<T>,
+) -> Option<T> {
+    let krate = resolver.krate()?;
+    // FIXME: maybe put the trait_env behind a query (need to figure out good input parameters for that)
+    let env = TraitEnvironment::lower(db, resolver);
+    // if ty is `impl Trait` or `dyn Trait`, the trait doesn't need to be in scope
+    let inherent_trait = ty.value.inherent_trait().into_iter();
+    // if we have `T: Trait` in the param env, the trait doesn't need to be in scope
+    let traits_from_env = env
+        .trait_predicates_for_self_ty(&ty.value)
+        .map(|tr| tr.trait_)
+        .flat_map(|t| all_super_traits(db, t));
+    let traits =
+        inherent_trait.chain(traits_from_env).chain(resolver.traits_in_scope(db).into_iter());
+    'traits: for t in traits {
+        let data = db.trait_data(t);
+
+        // we'll be lazy about checking whether the type implements the
+        // trait, but if we find out it doesn't, we'll skip the rest of the
+        // iteration
+        let mut known_implemented = false;
+        for (_name, item) in data.items.iter() {
+            if !is_valid_candidate(db, name, mode, (*item).into()) {
+                continue;
+            }
+            if !known_implemented {
+                let goal = generic_implements_goal(db, env.clone(), t, ty.clone());
+                if db.trait_solve(krate.into(), goal).is_none() {
+                    continue 'traits;
+                }
+            }
+            known_implemented = true;
+            if let Some(result) = callback(&ty.value, (*item).into()) {
+                return Some(result);
+            }
+        }
+    }
+    None
+}
+
+fn iterate_inherent_methods<T>(
+    ty: &Canonical<Ty>,
+    db: &impl HirDatabase,
+    name: Option<&Name>,
+    mode: LookupMode,
+    krate: CrateId,
+    mut callback: impl FnMut(&Ty, AssocItemId) -> Option<T>,
+) -> Option<T> {
+    for krate in ty.value.def_crates(db, krate)? {
+        let impls = db.impls_in_crate(krate);
+
+        for impl_block in impls.lookup_impl_blocks(&ty.value) {
+            for &item in db.impl_data(impl_block).items.iter() {
+                if !is_valid_candidate(db, name, mode, item) {
+                    continue;
+                }
+                if let Some(result) = callback(&ty.value, item.into()) {
+                    return Some(result);
+                }
+            }
+        }
+    }
+    None
+}
+
+fn is_valid_candidate(
+    db: &impl HirDatabase,
+    name: Option<&Name>,
+    mode: LookupMode,
+    item: AssocItemId,
+) -> bool {
+    match item {
+        AssocItemId::FunctionId(m) => {
+            let data = db.function_data(m);
+            name.map_or(true, |name| &data.name == name)
+                && (data.has_self_param || mode == LookupMode::Path)
+        }
+        AssocItemId::ConstId(c) => {
+            let data = db.const_data(c);
+            name.map_or(true, |name| data.name.as_ref() == Some(name)) && (mode == LookupMode::Path)
+        }
+        _ => false,
+    }
+}
+
+pub fn implements_trait(
+    ty: &Canonical<Ty>,
+    db: &impl HirDatabase,
+    resolver: &Resolver,
+    krate: CrateId,
+    trait_: TraitId,
+) -> bool {
+    if ty.value.inherent_trait() == Some(trait_) {
+        // FIXME this is a bit of a hack, since Chalk should say the same thing
+        // anyway, but currently Chalk doesn't implement `dyn/impl Trait` yet
+        return true;
+    }
+    let env = TraitEnvironment::lower(db, resolver);
+    let goal = generic_implements_goal(db, env, trait_, ty.clone());
+    let solution = db.trait_solve(krate.into(), goal);
+
+    solution.is_some()
+}
+
+/// This creates Substs for a trait with the given Self type and type variables
+/// for all other parameters, to query Chalk with it.
+fn generic_implements_goal(
+    db: &impl HirDatabase,
+    env: Arc<TraitEnvironment>,
+    trait_: TraitId,
+    self_ty: Canonical<Ty>,
+) -> Canonical<InEnvironment<super::Obligation>> {
+    let num_vars = self_ty.num_vars;
+    let substs = super::Substs::build_for_def(db, trait_)
+        .push(self_ty.value)
+        .fill_with_bound_vars(num_vars as u32)
+        .build();
+    let num_vars = substs.len() - 1 + self_ty.num_vars;
+    let trait_ref = TraitRef { trait_, substs };
+    let obligation = super::Obligation::Trait(trait_ref);
+    Canonical { num_vars, value: InEnvironment::new(env, obligation) }
+}
diff --git a/crates/ra_hir_ty/src/op.rs b/crates/ra_hir_ty/src/op.rs
new file mode 100644
index 000000000..09c47a76d
--- /dev/null
+++ b/crates/ra_hir_ty/src/op.rs
@@ -0,0 +1,50 @@
+//! FIXME: write short doc here
+use hir_def::expr::{BinaryOp, CmpOp};
+
+use super::{InferTy, Ty, TypeCtor};
+use crate::ApplicationTy;
+
+pub(super) fn binary_op_return_ty(op: BinaryOp, rhs_ty: Ty) -> Ty {
+    match op {
+        BinaryOp::LogicOp(_) | BinaryOp::CmpOp(_) => Ty::simple(TypeCtor::Bool),
+        BinaryOp::Assignment { .. } => Ty::unit(),
+        BinaryOp::ArithOp(_) => match rhs_ty {
+            Ty::Apply(ApplicationTy { ctor, .. }) => match ctor {
+                TypeCtor::Int(..) | TypeCtor::Float(..) => rhs_ty,
+                _ => Ty::Unknown,
+            },
+            Ty::Infer(InferTy::IntVar(..)) | Ty::Infer(InferTy::FloatVar(..)) => rhs_ty,
+            _ => Ty::Unknown,
+        },
+    }
+}
+
+pub(super) fn binary_op_rhs_expectation(op: BinaryOp, lhs_ty: Ty) -> Ty {
+    match op {
+        BinaryOp::LogicOp(..) => Ty::simple(TypeCtor::Bool),
+        BinaryOp::Assignment { op: None } | BinaryOp::CmpOp(CmpOp::Eq { negated: _ }) => {
+            match lhs_ty {
+                Ty::Apply(ApplicationTy { ctor, .. }) => match ctor {
+                    TypeCtor::Int(..)
+                    | TypeCtor::Float(..)
+                    | TypeCtor::Str
+                    | TypeCtor::Char
+                    | TypeCtor::Bool => lhs_ty,
+                    _ => Ty::Unknown,
+                },
+                Ty::Infer(InferTy::IntVar(..)) | Ty::Infer(InferTy::FloatVar(..)) => lhs_ty,
+                _ => Ty::Unknown,
+            }
+        }
+        BinaryOp::CmpOp(CmpOp::Ord { .. })
+        | BinaryOp::Assignment { op: Some(_) }
+        | BinaryOp::ArithOp(_) => match lhs_ty {
+            Ty::Apply(ApplicationTy { ctor, .. }) => match ctor {
+                TypeCtor::Int(..) | TypeCtor::Float(..) => lhs_ty,
+                _ => Ty::Unknown,
+            },
+            Ty::Infer(InferTy::IntVar(..)) | Ty::Infer(InferTy::FloatVar(..)) => lhs_ty,
+            _ => Ty::Unknown,
+        },
+    }
+}
diff --git a/crates/ra_hir_ty/src/primitive.rs b/crates/ra_hir_ty/src/primitive.rs
new file mode 100644
index 000000000..02a8179d9
--- /dev/null
+++ b/crates/ra_hir_ty/src/primitive.rs
@@ -0,0 +1,193 @@
+//! Defines primitive types, which have a couple of peculiarities:
+//!
+//! * during type inference, they can be uncertain (ie, `let x = 92;`)
+//! * they don't belong to any particular crate.
+
+use std::fmt;
+
+pub use hir_def::builtin_type::{BuiltinFloat, BuiltinInt, FloatBitness, IntBitness, Signedness};
+
+#[derive(Clone, Copy, Eq, PartialEq, Hash, Debug)]
+pub enum Uncertain<T> {
+    Unknown,
+    Known(T),
+}
+
+impl From<IntTy> for Uncertain<IntTy> {
+    fn from(ty: IntTy) -> Self {
+        Uncertain::Known(ty)
+    }
+}
+
+impl fmt::Display for Uncertain<IntTy> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match *self {
+            Uncertain::Unknown => write!(f, "{{integer}}"),
+            Uncertain::Known(ty) => write!(f, "{}", ty),
+        }
+    }
+}
+
+impl From<FloatTy> for Uncertain<FloatTy> {
+    fn from(ty: FloatTy) -> Self {
+        Uncertain::Known(ty)
+    }
+}
+
+impl fmt::Display for Uncertain<FloatTy> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match *self {
+            Uncertain::Unknown => write!(f, "{{float}}"),
+            Uncertain::Known(ty) => write!(f, "{}", ty),
+        }
+    }
+}
+
+#[derive(Copy, Clone, Eq, PartialEq, Hash)]
+pub struct IntTy {
+    pub signedness: Signedness,
+    pub bitness: IntBitness,
+}
+
+impl fmt::Debug for IntTy {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        fmt::Display::fmt(self, f)
+    }
+}
+
+impl fmt::Display for IntTy {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "{}", self.ty_to_string())
+    }
+}
+
+impl IntTy {
+    pub fn isize() -> IntTy {
+        IntTy { signedness: Signedness::Signed, bitness: IntBitness::Xsize }
+    }
+
+    pub fn i8() -> IntTy {
+        IntTy { signedness: Signedness::Signed, bitness: IntBitness::X8 }
+    }
+
+    pub fn i16() -> IntTy {
+        IntTy { signedness: Signedness::Signed, bitness: IntBitness::X16 }
+    }
+
+    pub fn i32() -> IntTy {
+        IntTy { signedness: Signedness::Signed, bitness: IntBitness::X32 }
+    }
+
+    pub fn i64() -> IntTy {
+        IntTy { signedness: Signedness::Signed, bitness: IntBitness::X64 }
+    }
+
+    pub fn i128() -> IntTy {
+        IntTy { signedness: Signedness::Signed, bitness: IntBitness::X128 }
+    }
+
+    pub fn usize() -> IntTy {
+        IntTy { signedness: Signedness::Unsigned, bitness: IntBitness::Xsize }
+    }
+
+    pub fn u8() -> IntTy {
+        IntTy { signedness: Signedness::Unsigned, bitness: IntBitness::X8 }
+    }
+
+    pub fn u16() -> IntTy {
+        IntTy { signedness: Signedness::Unsigned, bitness: IntBitness::X16 }
+    }
+
+    pub fn u32() -> IntTy {
+        IntTy { signedness: Signedness::Unsigned, bitness: IntBitness::X32 }
+    }
+
+    pub fn u64() -> IntTy {
+        IntTy { signedness: Signedness::Unsigned, bitness: IntBitness::X64 }
+    }
+
+    pub fn u128() -> IntTy {
+        IntTy { signedness: Signedness::Unsigned, bitness: IntBitness::X128 }
+    }
+
+    pub fn ty_to_string(self) -> &'static str {
+        match (self.signedness, self.bitness) {
+            (Signedness::Signed, IntBitness::Xsize) => "isize",
+            (Signedness::Signed, IntBitness::X8) => "i8",
+            (Signedness::Signed, IntBitness::X16) => "i16",
+            (Signedness::Signed, IntBitness::X32) => "i32",
+            (Signedness::Signed, IntBitness::X64) => "i64",
+            (Signedness::Signed, IntBitness::X128) => "i128",
+            (Signedness::Unsigned, IntBitness::Xsize) => "usize",
+            (Signedness::Unsigned, IntBitness::X8) => "u8",
+            (Signedness::Unsigned, IntBitness::X16) => "u16",
+            (Signedness::Unsigned, IntBitness::X32) => "u32",
+            (Signedness::Unsigned, IntBitness::X64) => "u64",
+            (Signedness::Unsigned, IntBitness::X128) => "u128",
+        }
+    }
+}
+
+#[derive(Copy, Clone, PartialEq, Eq, Hash)]
+pub struct FloatTy {
+    pub bitness: FloatBitness,
+}
+
+impl fmt::Debug for FloatTy {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        fmt::Display::fmt(self, f)
+    }
+}
+
+impl fmt::Display for FloatTy {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "{}", self.ty_to_string())
+    }
+}
+
+impl FloatTy {
+    pub fn f32() -> FloatTy {
+        FloatTy { bitness: FloatBitness::X32 }
+    }
+
+    pub fn f64() -> FloatTy {
+        FloatTy { bitness: FloatBitness::X64 }
+    }
+
+    pub fn ty_to_string(self) -> &'static str {
+        match self.bitness {
+            FloatBitness::X32 => "f32",
+            FloatBitness::X64 => "f64",
+        }
+    }
+}
+
+impl From<BuiltinInt> for IntTy {
+    fn from(t: BuiltinInt) -> Self {
+        IntTy { signedness: t.signedness, bitness: t.bitness }
+    }
+}
+
+impl From<BuiltinFloat> for FloatTy {
+    fn from(t: BuiltinFloat) -> Self {
+        FloatTy { bitness: t.bitness }
+    }
+}
+
+impl From<Option<BuiltinInt>> for Uncertain<IntTy> {
+    fn from(t: Option<BuiltinInt>) -> Self {
+        match t {
+            None => Uncertain::Unknown,
+            Some(t) => Uncertain::Known(t.into()),
+        }
+    }
+}
+
+impl From<Option<BuiltinFloat>> for Uncertain<FloatTy> {
+    fn from(t: Option<BuiltinFloat>) -> Self {
+        match t {
+            None => Uncertain::Unknown,
+            Some(t) => Uncertain::Known(t.into()),
+        }
+    }
+}
diff --git a/crates/ra_hir_ty/src/test_db.rs b/crates/ra_hir_ty/src/test_db.rs
new file mode 100644
index 000000000..1dc9793f9
--- /dev/null
+++ b/crates/ra_hir_ty/src/test_db.rs
@@ -0,0 +1,146 @@
+//! Database used for testing `hir`.
+
+use std::{
+    panic,
+    sync::{Arc, Mutex},
+};
+
+use hir_def::{db::DefDatabase, AssocItemId, ModuleDefId, ModuleId};
+use hir_expand::diagnostics::DiagnosticSink;
+use ra_db::{salsa, CrateId, FileId, FileLoader, FileLoaderDelegate, RelativePath, SourceDatabase};
+
+use crate::{db::HirDatabase, expr::ExprValidator};
+
+#[salsa::database(
+    ra_db::SourceDatabaseExtStorage,
+    ra_db::SourceDatabaseStorage,
+    hir_expand::db::AstDatabaseStorage,
+    hir_def::db::InternDatabaseStorage,
+    hir_def::db::DefDatabaseStorage,
+    crate::db::HirDatabaseStorage
+)]
+#[derive(Debug, Default)]
+pub struct TestDB {
+    events: Mutex<Option<Vec<salsa::Event<TestDB>>>>,
+    runtime: salsa::Runtime<TestDB>,
+}
+
+impl salsa::Database for TestDB {
+    fn salsa_runtime(&self) -> &salsa::Runtime<TestDB> {
+        &self.runtime
+    }
+
+    fn salsa_runtime_mut(&mut self) -> &mut salsa::Runtime<Self> {
+        &mut self.runtime
+    }
+
+    fn salsa_event(&self, event: impl Fn() -> salsa::Event<TestDB>) {
+        let mut events = self.events.lock().unwrap();
+        if let Some(events) = &mut *events {
+            events.push(event());
+        }
+    }
+}
+
+impl salsa::ParallelDatabase for TestDB {
+    fn snapshot(&self) -> salsa::Snapshot<TestDB> {
+        salsa::Snapshot::new(TestDB {
+            events: Default::default(),
+            runtime: self.runtime.snapshot(self),
+        })
+    }
+}
+
+impl panic::RefUnwindSafe for TestDB {}
+
+impl FileLoader for TestDB {
+    fn file_text(&self, file_id: FileId) -> Arc<String> {
+        FileLoaderDelegate(self).file_text(file_id)
+    }
+    fn resolve_relative_path(
+        &self,
+        anchor: FileId,
+        relative_path: &RelativePath,
+    ) -> Option<FileId> {
+        FileLoaderDelegate(self).resolve_relative_path(anchor, relative_path)
+    }
+    fn relevant_crates(&self, file_id: FileId) -> Arc<Vec<CrateId>> {
+        FileLoaderDelegate(self).relevant_crates(file_id)
+    }
+}
+
+impl TestDB {
+    pub fn module_for_file(&self, file_id: FileId) -> ModuleId {
+        for &krate in self.relevant_crates(file_id).iter() {
+            let crate_def_map = self.crate_def_map(krate);
+            for (local_id, data) in crate_def_map.modules.iter() {
+                if data.definition == Some(file_id) {
+                    return ModuleId { krate, local_id };
+                }
+            }
+        }
+        panic!("Can't find module for file")
+    }
+
+    // FIXME: don't duplicate this
+    pub fn diagnostics(&self) -> String {
+        let mut buf = String::new();
+        let crate_graph = self.crate_graph();
+        for krate in crate_graph.iter().next() {
+            let crate_def_map = self.crate_def_map(krate);
+
+            let mut fns = Vec::new();
+            for (module_id, _) in crate_def_map.modules.iter() {
+                for decl in crate_def_map[module_id].scope.declarations() {
+                    match decl {
+                        ModuleDefId::FunctionId(f) => fns.push(f),
+                        _ => (),
+                    }
+                }
+
+                for &impl_id in crate_def_map[module_id].impls.iter() {
+                    let impl_data = self.impl_data(impl_id);
+                    for item in impl_data.items.iter() {
+                        if let AssocItemId::FunctionId(f) = item {
+                            fns.push(*f)
+                        }
+                    }
+                }
+            }
+
+            for f in fns {
+                let infer = self.infer(f.into());
+                let mut sink = DiagnosticSink::new(|d| {
+                    buf += &format!("{:?}: {}\n", d.syntax_node(self).text(), d.message());
+                });
+                infer.add_diagnostics(self, f, &mut sink);
+                let mut validator = ExprValidator::new(f, infer, &mut sink);
+                validator.validate_body(self);
+            }
+        }
+        buf
+    }
+}
+
+impl TestDB {
+    pub fn log(&self, f: impl FnOnce()) -> Vec<salsa::Event<TestDB>> {
+        *self.events.lock().unwrap() = Some(Vec::new());
+        f();
+        self.events.lock().unwrap().take().unwrap()
+    }
+
+    pub fn log_executed(&self, f: impl FnOnce()) -> Vec<String> {
+        let events = self.log(f);
+        events
+            .into_iter()
+            .filter_map(|e| match e.kind {
+                // This pretty horrible, but `Debug` is the only way to inspect
+                // QueryDescriptor at the moment.
+                salsa::EventKind::WillExecute { database_key } => {
+                    Some(format!("{:?}", database_key))
+                }
+                _ => None,
+            })
+            .collect()
+    }
+}
diff --git a/crates/ra_hir_ty/src/tests.rs b/crates/ra_hir_ty/src/tests.rs
new file mode 100644
index 000000000..c8461b447
--- /dev/null
+++ b/crates/ra_hir_ty/src/tests.rs
@@ -0,0 +1,4958 @@
+mod never_type;
+mod coercion;
+
+use std::fmt::Write;
+use std::sync::Arc;
+
+use hir_def::{
+    body::BodySourceMap, db::DefDatabase, nameres::CrateDefMap, AssocItemId, DefWithBodyId,
+    LocalModuleId, Lookup, ModuleDefId,
+};
+use hir_expand::Source;
+use insta::assert_snapshot;
+use ra_db::{fixture::WithFixture, salsa::Database, FilePosition, SourceDatabase};
+use ra_syntax::{
+    algo,
+    ast::{self, AstNode},
+};
+use test_utils::covers;
+
+use crate::{db::HirDatabase, display::HirDisplay, test_db::TestDB, InferenceResult};
+
+// These tests compare the inference results for all expressions in a file
+// against snapshots of the expected results using insta. Use cargo-insta to
+// update the snapshots.
+
+#[test]
+fn cfg_impl_block() {
+    let (db, pos) = TestDB::with_position(
+        r#"
+//- /main.rs crate:main deps:foo cfg:test
+use foo::S as T;
+struct S;
+
+#[cfg(test)]
+impl S {
+    fn foo1(&self) -> i32 { 0 }
+}
+
+#[cfg(not(test))]
+impl S {
+    fn foo2(&self) -> i32 { 0 }
+}
+
+fn test() {
+    let t = (S.foo1(), S.foo2(), T.foo3(), T.foo4());
+    t<|>;
+}
+
+//- /foo.rs crate:foo
+struct S;
+
+#[cfg(not(test))]
+impl S {
+    fn foo3(&self) -> i32 { 0 }
+}
+
+#[cfg(test)]
+impl S {
+    fn foo4(&self) -> i32 { 0 }
+}
+"#,
+    );
+    assert_eq!("(i32, {unknown}, i32, {unknown})", type_at_pos(&db, pos));
+}
+
+#[test]
+fn infer_await() {
+    let (db, pos) = TestDB::with_position(
+        r#"
+//- /main.rs crate:main deps:std
+
+struct IntFuture;
+
+impl Future for IntFuture {
+    type Output = u64;
+}
+
+fn test() {
+    let r = IntFuture;
+    let v = r.await;
+    v<|>;
+}
+
+//- /std.rs crate:std
+#[prelude_import] use future::*;
+mod future {
+    trait Future {
+        type Output;
+    }
+}
+
+"#,
+    );
+    assert_eq!("u64", type_at_pos(&db, pos));
+}
+
+#[test]
+fn infer_box() {
+    let (db, pos) = TestDB::with_position(
+        r#"
+//- /main.rs crate:main deps:std
+
+fn test() {
+    let x = box 1;
+    let t = (x, box x, box &1, box [1]);
+    t<|>;
+}
+
+//- /std.rs crate:std
+#[prelude_import] use prelude::*;
+mod prelude {}
+
+mod boxed {
+    pub struct Box<T: ?Sized> {
+        inner: *mut T,
+    }
+}
+
+"#,
+    );
+    assert_eq!("(Box<i32>, Box<Box<i32>>, Box<&i32>, Box<[i32;_]>)", type_at_pos(&db, pos));
+}
+
+#[test]
+fn infer_adt_self() {
+    let (db, pos) = TestDB::with_position(
+        r#"
+//- /main.rs
+enum Nat { Succ(Self), Demo(Nat), Zero }
+
+fn test() {
+    let foo: Nat = Nat::Zero;
+    if let Nat::Succ(x) = foo {
+        x<|>
+    }
+}
+
+"#,
+    );
+    assert_eq!("Nat", type_at_pos(&db, pos));
+}
+
+#[test]
+fn infer_try() {
+    let (db, pos) = TestDB::with_position(
+        r#"
+//- /main.rs crate:main deps:std
+
+fn test() {
+    let r: Result<i32, u64> = Result::Ok(1);
+    let v = r?;
+    v<|>;
+}
+
+//- /std.rs crate:std
+
+#[prelude_import] use ops::*;
+mod ops {
+    trait Try {
+        type Ok;
+        type Error;
+    }
+}
+
+#[prelude_import] use result::*;
+mod result {
+    enum Result<O, E> {
+        Ok(O),
+        Err(E)
+    }
+
+    impl<O, E> crate::ops::Try for Result<O, E> {
+        type Ok = O;
+        type Error = E;
+    }
+}
+
+"#,
+    );
+    assert_eq!("i32", type_at_pos(&db, pos));
+}
+
+#[test]
+fn infer_for_loop() {
+    let (db, pos) = TestDB::with_position(
+        r#"
+//- /main.rs crate:main deps:std
+
+use std::collections::Vec;
+
+fn test() {
+    let v = Vec::new();
+    v.push("foo");
+    for x in v {
+        x<|>;
+    }
+}
+
+//- /std.rs crate:std
+
+#[prelude_import] use iter::*;
+mod iter {
+    trait IntoIterator {
+        type Item;
+    }
+}
+
+mod collections {
+    struct Vec<T> {}
+    impl<T> Vec<T> {
+        fn new() -> Self { Vec {} }
+        fn push(&mut self, t: T) { }
+    }
+
+    impl<T> crate::iter::IntoIterator for Vec<T> {
+        type Item=T;
+    }
+}
+"#,
+    );
+    assert_eq!("&str", type_at_pos(&db, pos));
+}
+
+#[test]
+fn infer_while_let() {
+    let (db, pos) = TestDB::with_position(
+        r#"
+//- /main.rs
+enum Option<T> { Some(T), None }
+
+fn test() {
+    let foo: Option<f32> = None;
+    while let Option::Some(x) = foo {
+        <|>x
+    }
+}
+
+"#,
+    );
+    assert_eq!("f32", type_at_pos(&db, pos));
+}
+
+#[test]
+fn infer_basics() {
+    assert_snapshot!(
+        infer(r#"
+fn test(a: u32, b: isize, c: !, d: &str) {
+    a;
+    b;
+    c;
+    d;
+    1usize;
+    1isize;
+    "test";
+    1.0f32;
+}"#),
+        @r###"
+    [9; 10) 'a': u32
+    [17; 18) 'b': isize
+    [27; 28) 'c': !
+    [33; 34) 'd': &str
+    [42; 121) '{     ...f32; }': !
+    [48; 49) 'a': u32
+    [55; 56) 'b': isize
+    [62; 63) 'c': !
+    [69; 70) 'd': &str
+    [76; 82) '1usize': usize
+    [88; 94) '1isize': isize
+    [100; 106) '"test"': &str
+    [112; 118) '1.0f32': f32
+    "###
+    );
+}
+
+#[test]
+fn infer_let() {
+    assert_snapshot!(
+        infer(r#"
+fn test() {
+    let a = 1isize;
+    let b: usize = 1;
+    let c = b;
+    let d: u32;
+    let e;
+    let f: i32 = e;
+}
+"#),
+        @r###"
+    [11; 118) '{     ...= e; }': ()
+    [21; 22) 'a': isize
+    [25; 31) '1isize': isize
+    [41; 42) 'b': usize
+    [52; 53) '1': usize
+    [63; 64) 'c': usize
+    [67; 68) 'b': usize
+    [78; 79) 'd': u32
+    [94; 95) 'e': i32
+    [105; 106) 'f': i32
+    [114; 115) 'e': i32
+    "###
+    );
+}
+
+#[test]
+fn infer_paths() {
+    assert_snapshot!(
+        infer(r#"
+fn a() -> u32 { 1 }
+
+mod b {
+    fn c() -> u32 { 1 }
+}
+
+fn test() {
+    a();
+    b::c();
+}
+"#),
+        @r###"
+    [15; 20) '{ 1 }': u32
+    [17; 18) '1': u32
+    [48; 53) '{ 1 }': u32
+    [50; 51) '1': u32
+    [67; 91) '{     ...c(); }': ()
+    [73; 74) 'a': fn a() -> u32
+    [73; 76) 'a()': u32
+    [82; 86) 'b::c': fn c() -> u32
+    [82; 88) 'b::c()': u32
+    "###
+    );
+}
+
+#[test]
+fn infer_path_type() {
+    assert_snapshot!(
+        infer(r#"
+struct S;
+
+impl S {
+    fn foo() -> i32 { 1 }
+}
+
+fn test() {
+    S::foo();
+    <S>::foo();
+}
+"#),
+        @r###"
+    [41; 46) '{ 1 }': i32
+    [43; 44) '1': i32
+    [60; 93) '{     ...o(); }': ()
+    [66; 72) 'S::foo': fn foo() -> i32
+    [66; 74) 'S::foo()': i32
+    [80; 88) '<S>::foo': fn foo() -> i32
+    [80; 90) '<S>::foo()': i32
+    "###
+    );
+}
+
+#[test]
+fn infer_slice_method() {
+    assert_snapshot!(
+        infer(r#"
+#[lang = "slice"]
+impl<T> [T] {
+    fn foo(&self) -> T {
+        loop {}
+    }
+}
+
+#[lang = "slice_alloc"]
+impl<T> [T] {}
+
+fn test() {
+    <[_]>::foo(b"foo");
+}
+"#),
+        @r###"
+    [45; 49) 'self': &[T]
+    [56; 79) '{     ...     }': T
+    [66; 73) 'loop {}': !
+    [71; 73) '{}': ()
+    [133; 160) '{     ...o"); }': ()
+    [139; 149) '<[_]>::foo': fn foo<u8>(&[T]) -> T
+    [139; 157) '<[_]>:..."foo")': u8
+    [150; 156) 'b"foo"': &[u8]
+    "###
+    );
+}
+
+#[test]
+fn infer_struct() {
+    assert_snapshot!(
+        infer(r#"
+struct A {
+    b: B,
+    c: C,
+}
+struct B;
+struct C(usize);
+
+fn test() {
+    let c = C(1);
+    B;
+    let a: A = A { b: B, c: C(1) };
+    a.b;
+    a.c;
+}
+"#),
+        @r###"
+    [72; 154) '{     ...a.c; }': ()
+    [82; 83) 'c': C
+    [86; 87) 'C': C(usize) -> C
+    [86; 90) 'C(1)': C
+    [88; 89) '1': usize
+    [96; 97) 'B': B
+    [107; 108) 'a': A
+    [114; 133) 'A { b:...C(1) }': A
+    [121; 122) 'B': B
+    [127; 128) 'C': C(usize) -> C
+    [127; 131) 'C(1)': C
+    [129; 130) '1': usize
+    [139; 140) 'a': A
+    [139; 142) 'a.b': B
+    [148; 149) 'a': A
+    [148; 151) 'a.c': C
+    "###
+    );
+}
+
+#[test]
+fn infer_enum() {
+    assert_snapshot!(
+        infer(r#"
+enum E {
+  V1 { field: u32 },
+  V2
+}
+fn test() {
+  E::V1 { field: 1 };
+  E::V2;
+}"#),
+        @r###"
+    [48; 82) '{   E:...:V2; }': ()
+    [52; 70) 'E::V1 ...d: 1 }': E
+    [67; 68) '1': u32
+    [74; 79) 'E::V2': E
+    "###
+    );
+}
+
+#[test]
+fn infer_refs() {
+    assert_snapshot!(
+        infer(r#"
+fn test(a: &u32, b: &mut u32, c: *const u32, d: *mut u32) {
+    a;
+    *a;
+    &a;
+    &mut a;
+    b;
+    *b;
+    &b;
+    c;
+    *c;
+    d;
+    *d;
+}
+"#),
+        @r###"
+    [9; 10) 'a': &u32
+    [18; 19) 'b': &mut u32
+    [31; 32) 'c': *const u32
+    [46; 47) 'd': *mut u32
+    [59; 150) '{     ... *d; }': ()
+    [65; 66) 'a': &u32
+    [72; 74) '*a': u32
+    [73; 74) 'a': &u32
+    [80; 82) '&a': &&u32
+    [81; 82) 'a': &u32
+    [88; 94) '&mut a': &mut &u32
+    [93; 94) 'a': &u32
+    [100; 101) 'b': &mut u32
+    [107; 109) '*b': u32
+    [108; 109) 'b': &mut u32
+    [115; 117) '&b': &&mut u32
+    [116; 117) 'b': &mut u32
+    [123; 124) 'c': *const u32
+    [130; 132) '*c': u32
+    [131; 132) 'c': *const u32
+    [138; 139) 'd': *mut u32
+    [145; 147) '*d': u32
+    [146; 147) 'd': *mut u32
+    "###
+    );
+}
+
+#[test]
+fn infer_literals() {
+    assert_snapshot!(
+        infer(r##"
+fn test() {
+    5i32;
+    5f32;
+    5f64;
+    "hello";
+    b"bytes";
+    'c';
+    b'b';
+    3.14;
+    5000;
+    false;
+    true;
+    r#"
+        //! doc
+        // non-doc
+        mod foo {}
+        "#;
+    br#"yolo"#;
+}
+"##),
+        @r###"
+    [11; 221) '{     ...o"#; }': ()
+    [17; 21) '5i32': i32
+    [27; 31) '5f32': f32
+    [37; 41) '5f64': f64
+    [47; 54) '"hello"': &str
+    [60; 68) 'b"bytes"': &[u8]
+    [74; 77) ''c'': char
+    [83; 87) 'b'b'': u8
+    [93; 97) '3.14': f64
+    [103; 107) '5000': i32
+    [113; 118) 'false': bool
+    [124; 128) 'true': bool
+    [134; 202) 'r#"   ...    "#': &str
+    [208; 218) 'br#"yolo"#': &[u8]
+    "###
+    );
+}
+
+#[test]
+fn infer_unary_op() {
+    assert_snapshot!(
+        infer(r#"
+enum SomeType {}
+
+fn test(x: SomeType) {
+    let b = false;
+    let c = !b;
+    let a = 100;
+    let d: i128 = -a;
+    let e = -100;
+    let f = !!!true;
+    let g = !42;
+    let h = !10u32;
+    let j = !a;
+    -3.14;
+    !3;
+    -x;
+    !x;
+    -"hello";
+    !"hello";
+}
+"#),
+        @r###"
+    [27; 28) 'x': SomeType
+    [40; 272) '{     ...lo"; }': ()
+    [50; 51) 'b': bool
+    [54; 59) 'false': bool
+    [69; 70) 'c': bool
+    [73; 75) '!b': bool
+    [74; 75) 'b': bool
+    [85; 86) 'a': i128
+    [89; 92) '100': i128
+    [102; 103) 'd': i128
+    [112; 114) '-a': i128
+    [113; 114) 'a': i128
+    [124; 125) 'e': i32
+    [128; 132) '-100': i32
+    [129; 132) '100': i32
+    [142; 143) 'f': bool
+    [146; 153) '!!!true': bool
+    [147; 153) '!!true': bool
+    [148; 153) '!true': bool
+    [149; 153) 'true': bool
+    [163; 164) 'g': i32
+    [167; 170) '!42': i32
+    [168; 170) '42': i32
+    [180; 181) 'h': u32
+    [184; 190) '!10u32': u32
+    [185; 190) '10u32': u32
+    [200; 201) 'j': i128
+    [204; 206) '!a': i128
+    [205; 206) 'a': i128
+    [212; 217) '-3.14': f64
+    [213; 217) '3.14': f64
+    [223; 225) '!3': i32
+    [224; 225) '3': i32
+    [231; 233) '-x': {unknown}
+    [232; 233) 'x': SomeType
+    [239; 241) '!x': {unknown}
+    [240; 241) 'x': SomeType
+    [247; 255) '-"hello"': {unknown}
+    [248; 255) '"hello"': &str
+    [261; 269) '!"hello"': {unknown}
+    [262; 269) '"hello"': &str
+    "###
+    );
+}
+
+#[test]
+fn infer_backwards() {
+    assert_snapshot!(
+        infer(r#"
+fn takes_u32(x: u32) {}
+
+struct S { i32_field: i32 }
+
+fn test() -> &mut &f64 {
+    let a = unknown_function();
+    takes_u32(a);
+    let b = unknown_function();
+    S { i32_field: b };
+    let c = unknown_function();
+    &mut &c
+}
+"#),
+        @r###"
+    [14; 15) 'x': u32
+    [22; 24) '{}': ()
+    [78; 231) '{     ...t &c }': &mut &f64
+    [88; 89) 'a': u32
+    [92; 108) 'unknow...nction': {unknown}
+    [92; 110) 'unknow...tion()': u32
+    [116; 125) 'takes_u32': fn takes_u32(u32) -> ()
+    [116; 128) 'takes_u32(a)': ()
+    [126; 127) 'a': u32
+    [138; 139) 'b': i32
+    [142; 158) 'unknow...nction': {unknown}
+    [142; 160) 'unknow...tion()': i32
+    [166; 184) 'S { i3...d: b }': S
+    [181; 182) 'b': i32
+    [194; 195) 'c': f64
+    [198; 214) 'unknow...nction': {unknown}
+    [198; 216) 'unknow...tion()': f64
+    [222; 229) '&mut &c': &mut &f64
+    [227; 229) '&c': &f64
+    [228; 229) 'c': f64
+    "###
+    );
+}
+
+#[test]
+fn infer_self() {
+    assert_snapshot!(
+        infer(r#"
+struct S;
+
+impl S {
+    fn test(&self) {
+        self;
+    }
+    fn test2(self: &Self) {
+        self;
+    }
+    fn test3() -> Self {
+        S {}
+    }
+    fn test4() -> Self {
+        Self {}
+    }
+}
+"#),
+        @r###"
+    [34; 38) 'self': &S
+    [40; 61) '{     ...     }': ()
+    [50; 54) 'self': &S
+    [75; 79) 'self': &S
+    [88; 109) '{     ...     }': ()
+    [98; 102) 'self': &S
+    [133; 153) '{     ...     }': S
+    [143; 147) 'S {}': S
+    [177; 200) '{     ...     }': S
+    [187; 194) 'Self {}': S
+    "###
+    );
+}
+
+#[test]
+fn infer_binary_op() {
+    assert_snapshot!(
+        infer(r#"
+fn f(x: bool) -> i32 {
+    0i32
+}
+
+fn test() -> bool {
+    let x = a && b;
+    let y = true || false;
+    let z = x == y;
+    let t = x != y;
+    let minus_forty: isize = -40isize;
+    let h = minus_forty <= CONST_2;
+    let c = f(z || y) + 5;
+    let d = b;
+    let g = minus_forty ^= i;
+    let ten: usize = 10;
+    let ten_is_eleven = ten == some_num;
+
+    ten < 3
+}
+"#),
+        @r###"
+    [6; 7) 'x': bool
+    [22; 34) '{     0i32 }': i32
+    [28; 32) '0i32': i32
+    [54; 370) '{     ... < 3 }': bool
+    [64; 65) 'x': bool
+    [68; 69) 'a': bool
+    [68; 74) 'a && b': bool
+    [73; 74) 'b': bool
+    [84; 85) 'y': bool
+    [88; 92) 'true': bool
+    [88; 101) 'true || false': bool
+    [96; 101) 'false': bool
+    [111; 112) 'z': bool
+    [115; 116) 'x': bool
+    [115; 121) 'x == y': bool
+    [120; 121) 'y': bool
+    [131; 132) 't': bool
+    [135; 136) 'x': bool
+    [135; 141) 'x != y': bool
+    [140; 141) 'y': bool
+    [151; 162) 'minus_forty': isize
+    [172; 180) '-40isize': isize
+    [173; 180) '40isize': isize
+    [190; 191) 'h': bool
+    [194; 205) 'minus_forty': isize
+    [194; 216) 'minus_...ONST_2': bool
+    [209; 216) 'CONST_2': isize
+    [226; 227) 'c': i32
+    [230; 231) 'f': fn f(bool) -> i32
+    [230; 239) 'f(z || y)': i32
+    [230; 243) 'f(z || y) + 5': i32
+    [232; 233) 'z': bool
+    [232; 238) 'z || y': bool
+    [237; 238) 'y': bool
+    [242; 243) '5': i32
+    [253; 254) 'd': {unknown}
+    [257; 258) 'b': {unknown}
+    [268; 269) 'g': ()
+    [272; 283) 'minus_forty': isize
+    [272; 288) 'minus_...y ^= i': ()
+    [287; 288) 'i': isize
+    [298; 301) 'ten': usize
+    [311; 313) '10': usize
+    [323; 336) 'ten_is_eleven': bool
+    [339; 342) 'ten': usize
+    [339; 354) 'ten == some_num': bool
+    [346; 354) 'some_num': usize
+    [361; 364) 'ten': usize
+    [361; 368) 'ten < 3': bool
+    [367; 368) '3': usize
+    "###
+    );
+}
+
+#[test]
+fn infer_field_autoderef() {
+    assert_snapshot!(
+        infer(r#"
+struct A {
+    b: B,
+}
+struct B;
+
+fn test1(a: A) {
+    let a1 = a;
+    a1.b;
+    let a2 = &a;
+    a2.b;
+    let a3 = &mut a;
+    a3.b;
+    let a4 = &&&&&&&a;
+    a4.b;
+    let a5 = &mut &&mut &&mut a;
+    a5.b;
+}
+
+fn test2(a1: *const A, a2: *mut A) {
+    a1.b;
+    a2.b;
+}
+"#),
+        @r###"
+    [44; 45) 'a': A
+    [50; 213) '{     ...5.b; }': ()
+    [60; 62) 'a1': A
+    [65; 66) 'a': A
+    [72; 74) 'a1': A
+    [72; 76) 'a1.b': B
+    [86; 88) 'a2': &A
+    [91; 93) '&a': &A
+    [92; 93) 'a': A
+    [99; 101) 'a2': &A
+    [99; 103) 'a2.b': B
+    [113; 115) 'a3': &mut A
+    [118; 124) '&mut a': &mut A
+    [123; 124) 'a': A
+    [130; 132) 'a3': &mut A
+    [130; 134) 'a3.b': B
+    [144; 146) 'a4': &&&&&&&A
+    [149; 157) '&&&&&&&a': &&&&&&&A
+    [150; 157) '&&&&&&a': &&&&&&A
+    [151; 157) '&&&&&a': &&&&&A
+    [152; 157) '&&&&a': &&&&A
+    [153; 157) '&&&a': &&&A
+    [154; 157) '&&a': &&A
+    [155; 157) '&a': &A
+    [156; 157) 'a': A
+    [163; 165) 'a4': &&&&&&&A
+    [163; 167) 'a4.b': B
+    [177; 179) 'a5': &mut &&mut &&mut A
+    [182; 200) '&mut &...&mut a': &mut &&mut &&mut A
+    [187; 200) '&&mut &&mut a': &&mut &&mut A
+    [188; 200) '&mut &&mut a': &mut &&mut A
+    [193; 200) '&&mut a': &&mut A
+    [194; 200) '&mut a': &mut A
+    [199; 200) 'a': A
+    [206; 208) 'a5': &mut &&mut &&mut A
+    [206; 210) 'a5.b': B
+    [224; 226) 'a1': *const A
+    [238; 240) 'a2': *mut A
+    [250; 273) '{     ...2.b; }': ()
+    [256; 258) 'a1': *const A
+    [256; 260) 'a1.b': B
+    [266; 268) 'a2': *mut A
+    [266; 270) 'a2.b': B
+    "###
+    );
+}
+
+#[test]
+fn infer_argument_autoderef() {
+    assert_snapshot!(
+        infer(r#"
+#[lang = "deref"]
+pub trait Deref {
+    type Target;
+    fn deref(&self) -> &Self::Target;
+}
+
+struct A<T>(T);
+
+impl<T> A<T> {
+    fn foo(&self) -> &T {
+        &self.0
+    }
+}
+
+struct B<T>(T);
+
+impl<T> Deref for B<T> {
+    type Target = T;
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+fn test() {
+    let t = A::foo(&&B(B(A(42))));
+}
+"#),
+        @r###"
+    [68; 72) 'self': &Self
+    [139; 143) 'self': &A<T>
+    [151; 174) '{     ...     }': &T
+    [161; 168) '&self.0': &T
+    [162; 166) 'self': &A<T>
+    [162; 168) 'self.0': T
+    [255; 259) 'self': &B<T>
+    [278; 301) '{     ...     }': &T
+    [288; 295) '&self.0': &T
+    [289; 293) 'self': &B<T>
+    [289; 295) 'self.0': T
+    [315; 353) '{     ...))); }': ()
+    [325; 326) 't': &i32
+    [329; 335) 'A::foo': fn foo<i32>(&A<T>) -> &T
+    [329; 350) 'A::foo...42))))': &i32
+    [336; 349) '&&B(B(A(42)))': &&B<B<A<i32>>>
+    [337; 349) '&B(B(A(42)))': &B<B<A<i32>>>
+    [338; 339) 'B': B<B<A<i32>>>(T) -> B<T>
+    [338; 349) 'B(B(A(42)))': B<B<A<i32>>>
+    [340; 341) 'B': B<A<i32>>(T) -> B<T>
+    [340; 348) 'B(A(42))': B<A<i32>>
+    [342; 343) 'A': A<i32>(T) -> A<T>
+    [342; 347) 'A(42)': A<i32>
+    [344; 346) '42': i32
+    "###
+    );
+}
+
+#[test]
+fn infer_method_argument_autoderef() {
+    assert_snapshot!(
+        infer(r#"
+#[lang = "deref"]
+pub trait Deref {
+    type Target;
+    fn deref(&self) -> &Self::Target;
+}
+
+struct A<T>(*mut T);
+
+impl<T> A<T> {
+    fn foo(&self, x: &A<T>) -> &T {
+        &*x.0
+    }
+}
+
+struct B<T>(T);
+
+impl<T> Deref for B<T> {
+    type Target = T;
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+fn test(a: A<i32>) {
+    let t = A(0 as *mut _).foo(&&B(B(a)));
+}
+"#),
+        @r###"
+    [68; 72) 'self': &Self
+    [144; 148) 'self': &A<T>
+    [150; 151) 'x': &A<T>
+    [166; 187) '{     ...     }': &T
+    [176; 181) '&*x.0': &T
+    [177; 181) '*x.0': T
+    [178; 179) 'x': &A<T>
+    [178; 181) 'x.0': *mut T
+    [268; 272) 'self': &B<T>
+    [291; 314) '{     ...     }': &T
+    [301; 308) '&self.0': &T
+    [302; 306) 'self': &B<T>
+    [302; 308) 'self.0': T
+    [326; 327) 'a': A<i32>
+    [337; 383) '{     ...))); }': ()
+    [347; 348) 't': &i32
+    [351; 352) 'A': A<i32>(*mut T) -> A<T>
+    [351; 365) 'A(0 as *mut _)': A<i32>
+    [351; 380) 'A(0 as...B(a)))': &i32
+    [353; 354) '0': i32
+    [353; 364) '0 as *mut _': *mut i32
+    [370; 379) '&&B(B(a))': &&B<B<A<i32>>>
+    [371; 379) '&B(B(a))': &B<B<A<i32>>>
+    [372; 373) 'B': B<B<A<i32>>>(T) -> B<T>
+    [372; 379) 'B(B(a))': B<B<A<i32>>>
+    [374; 375) 'B': B<A<i32>>(T) -> B<T>
+    [374; 378) 'B(a)': B<A<i32>>
+    [376; 377) 'a': A<i32>
+    "###
+    );
+}
+
+#[test]
+fn bug_484() {
+    assert_snapshot!(
+        infer(r#"
+fn test() {
+   let x = if true {};
+}
+"#),
+        @r###"
+    [11; 37) '{    l... {}; }': ()
+    [20; 21) 'x': ()
+    [24; 34) 'if true {}': ()
+    [27; 31) 'true': bool
+    [32; 34) '{}': ()
+    "###
+    );
+}
+
+#[test]
+fn infer_in_elseif() {
+    assert_snapshot!(
+        infer(r#"
+struct Foo { field: i32 }
+fn main(foo: Foo) {
+    if true {
+
+    } else if false {
+        foo.field
+    }
+}
+"#),
+        @r###"
+    [35; 38) 'foo': Foo
+    [45; 109) '{     ...   } }': ()
+    [51; 107) 'if tru...     }': ()
+    [54; 58) 'true': bool
+    [59; 67) '{      }': ()
+    [73; 107) 'if fal...     }': ()
+    [76; 81) 'false': bool
+    [82; 107) '{     ...     }': i32
+    [92; 95) 'foo': Foo
+    [92; 101) 'foo.field': i32
+    "###
+    )
+}
+
+#[test]
+fn infer_if_match_with_return() {
+    assert_snapshot!(
+        infer(r#"
+fn foo() {
+    let _x1 = if true {
+        1
+    } else {
+        return;
+    };
+    let _x2 = if true {
+        2
+    } else {
+        return
+    };
+    let _x3 = match true {
+        true => 3,
+        _ => {
+            return;
+        }
+    };
+    let _x4 = match true {
+        true => 4,
+        _ => return
+    };
+}"#),
+        @r###"
+    [10; 323) '{     ...  }; }': ()
+    [20; 23) '_x1': i32
+    [26; 80) 'if tru...     }': i32
+    [29; 33) 'true': bool
+    [34; 51) '{     ...     }': i32
+    [44; 45) '1': i32
+    [57; 80) '{     ...     }': !
+    [67; 73) 'return': !
+    [90; 93) '_x2': i32
+    [96; 149) 'if tru...     }': i32
+    [99; 103) 'true': bool
+    [104; 121) '{     ...     }': i32
+    [114; 115) '2': i32
+    [127; 149) '{     ...     }': !
+    [137; 143) 'return': !
+    [159; 162) '_x3': i32
+    [165; 247) 'match ...     }': i32
+    [171; 175) 'true': bool
+    [186; 190) 'true': bool
+    [194; 195) '3': i32
+    [205; 206) '_': bool
+    [210; 241) '{     ...     }': !
+    [224; 230) 'return': !
+    [257; 260) '_x4': i32
+    [263; 320) 'match ...     }': i32
+    [269; 273) 'true': bool
+    [284; 288) 'true': bool
+    [292; 293) '4': i32
+    [303; 304) '_': bool
+    [308; 314) 'return': !
+    "###
+    )
+}
+
+#[test]
+fn infer_inherent_method() {
+    assert_snapshot!(
+        infer(r#"
+struct A;
+
+impl A {
+    fn foo(self, x: u32) -> i32 {}
+}
+
+mod b {
+    impl super::A {
+        fn bar(&self, x: u64) -> i64 {}
+    }
+}
+
+fn test(a: A) {
+    a.foo(1);
+    (&a).bar(1);
+    a.bar(1);
+}
+"#),
+        @r###"
+    [32; 36) 'self': A
+    [38; 39) 'x': u32
+    [53; 55) '{}': ()
+    [103; 107) 'self': &A
+    [109; 110) 'x': u64
+    [124; 126) '{}': ()
+    [144; 145) 'a': A
+    [150; 198) '{     ...(1); }': ()
+    [156; 157) 'a': A
+    [156; 164) 'a.foo(1)': i32
+    [162; 163) '1': u32
+    [170; 181) '(&a).bar(1)': i64
+    [171; 173) '&a': &A
+    [172; 173) 'a': A
+    [179; 180) '1': u64
+    [187; 188) 'a': A
+    [187; 195) 'a.bar(1)': i64
+    [193; 194) '1': u64
+    "###
+    );
+}
+
+#[test]
+fn infer_inherent_method_str() {
+    assert_snapshot!(
+        infer(r#"
+#[lang = "str"]
+impl str {
+    fn foo(&self) -> i32 {}
+}
+
+fn test() {
+    "foo".foo();
+}
+"#),
+        @r###"
+    [40; 44) 'self': &str
+    [53; 55) '{}': ()
+    [69; 89) '{     ...o(); }': ()
+    [75; 80) '"foo"': &str
+    [75; 86) '"foo".foo()': i32
+    "###
+    );
+}
+
+#[test]
+fn infer_tuple() {
+    assert_snapshot!(
+        infer(r#"
+fn test(x: &str, y: isize) {
+    let a: (u32, &str) = (1, "a");
+    let b = (a, x);
+    let c = (y, x);
+    let d = (c, x);
+    let e = (1, "e");
+    let f = (e, "d");
+}
+"#),
+        @r###"
+    [9; 10) 'x': &str
+    [18; 19) 'y': isize
+    [28; 170) '{     ...d"); }': ()
+    [38; 39) 'a': (u32, &str)
+    [55; 63) '(1, "a")': (u32, &str)
+    [56; 57) '1': u32
+    [59; 62) '"a"': &str
+    [73; 74) 'b': ((u32, &str), &str)
+    [77; 83) '(a, x)': ((u32, &str), &str)
+    [78; 79) 'a': (u32, &str)
+    [81; 82) 'x': &str
+    [93; 94) 'c': (isize, &str)
+    [97; 103) '(y, x)': (isize, &str)
+    [98; 99) 'y': isize
+    [101; 102) 'x': &str
+    [113; 114) 'd': ((isize, &str), &str)
+    [117; 123) '(c, x)': ((isize, &str), &str)
+    [118; 119) 'c': (isize, &str)
+    [121; 122) 'x': &str
+    [133; 134) 'e': (i32, &str)
+    [137; 145) '(1, "e")': (i32, &str)
+    [138; 139) '1': i32
+    [141; 144) '"e"': &str
+    [155; 156) 'f': ((i32, &str), &str)
+    [159; 167) '(e, "d")': ((i32, &str), &str)
+    [160; 161) 'e': (i32, &str)
+    [163; 166) '"d"': &str
+    "###
+    );
+}
+
+#[test]
+fn infer_array() {
+    assert_snapshot!(
+        infer(r#"
+fn test(x: &str, y: isize) {
+    let a = [x];
+    let b = [a, a];
+    let c = [b, b];
+
+    let d = [y, 1, 2, 3];
+    let d = [1, y, 2, 3];
+    let e = [y];
+    let f = [d, d];
+    let g = [e, e];
+
+    let h = [1, 2];
+    let i = ["a", "b"];
+
+    let b = [a, ["b"]];
+    let x: [u8; 0] = [];
+}
+"#),
+        @r###"
+    [9; 10) 'x': &str
+    [18; 19) 'y': isize
+    [28; 293) '{     ... []; }': ()
+    [38; 39) 'a': [&str;_]
+    [42; 45) '[x]': [&str;_]
+    [43; 44) 'x': &str
+    [55; 56) 'b': [[&str;_];_]
+    [59; 65) '[a, a]': [[&str;_];_]
+    [60; 61) 'a': [&str;_]
+    [63; 64) 'a': [&str;_]
+    [75; 76) 'c': [[[&str;_];_];_]
+    [79; 85) '[b, b]': [[[&str;_];_];_]
+    [80; 81) 'b': [[&str;_];_]
+    [83; 84) 'b': [[&str;_];_]
+    [96; 97) 'd': [isize;_]
+    [100; 112) '[y, 1, 2, 3]': [isize;_]
+    [101; 102) 'y': isize
+    [104; 105) '1': isize
+    [107; 108) '2': isize
+    [110; 111) '3': isize
+    [122; 123) 'd': [isize;_]
+    [126; 138) '[1, y, 2, 3]': [isize;_]
+    [127; 128) '1': isize
+    [130; 131) 'y': isize
+    [133; 134) '2': isize
+    [136; 137) '3': isize
+    [148; 149) 'e': [isize;_]
+    [152; 155) '[y]': [isize;_]
+    [153; 154) 'y': isize
+    [165; 166) 'f': [[isize;_];_]
+    [169; 175) '[d, d]': [[isize;_];_]
+    [170; 171) 'd': [isize;_]
+    [173; 174) 'd': [isize;_]
+    [185; 186) 'g': [[isize;_];_]
+    [189; 195) '[e, e]': [[isize;_];_]
+    [190; 191) 'e': [isize;_]
+    [193; 194) 'e': [isize;_]
+    [206; 207) 'h': [i32;_]
+    [210; 216) '[1, 2]': [i32;_]
+    [211; 212) '1': i32
+    [214; 215) '2': i32
+    [226; 227) 'i': [&str;_]
+    [230; 240) '["a", "b"]': [&str;_]
+    [231; 234) '"a"': &str
+    [236; 239) '"b"': &str
+    [251; 252) 'b': [[&str;_];_]
+    [255; 265) '[a, ["b"]]': [[&str;_];_]
+    [256; 257) 'a': [&str;_]
+    [259; 264) '["b"]': [&str;_]
+    [260; 263) '"b"': &str
+    [275; 276) 'x': [u8;_]
+    [288; 290) '[]': [u8;_]
+    "###
+    );
+}
+
+#[test]
+fn infer_pattern() {
+    assert_snapshot!(
+        infer(r#"
+fn test(x: &i32) {
+    let y = x;
+    let &z = x;
+    let a = z;
+    let (c, d) = (1, "hello");
+
+    for (e, f) in some_iter {
+        let g = e;
+    }
+
+    if let [val] = opt {
+        let h = val;
+    }
+
+    let lambda = |a: u64, b, c: i32| { a + b; c };
+
+    let ref ref_to_x = x;
+    let mut mut_x = x;
+    let ref mut mut_ref_to_x = x;
+    let k = mut_ref_to_x;
+}
+"#),
+        @r###"
+    [9; 10) 'x': &i32
+    [18; 369) '{     ...o_x; }': ()
+    [28; 29) 'y': &i32
+    [32; 33) 'x': &i32
+    [43; 45) '&z': &i32
+    [44; 45) 'z': i32
+    [48; 49) 'x': &i32
+    [59; 60) 'a': i32
+    [63; 64) 'z': i32
+    [74; 80) '(c, d)': (i32, &str)
+    [75; 76) 'c': i32
+    [78; 79) 'd': &str
+    [83; 95) '(1, "hello")': (i32, &str)
+    [84; 85) '1': i32
+    [87; 94) '"hello"': &str
+    [102; 152) 'for (e...     }': ()
+    [106; 112) '(e, f)': ({unknown}, {unknown})
+    [107; 108) 'e': {unknown}
+    [110; 111) 'f': {unknown}
+    [116; 125) 'some_iter': {unknown}
+    [126; 152) '{     ...     }': ()
+    [140; 141) 'g': {unknown}
+    [144; 145) 'e': {unknown}
+    [158; 205) 'if let...     }': ()
+    [165; 170) '[val]': {unknown}
+    [173; 176) 'opt': {unknown}
+    [177; 205) '{     ...     }': ()
+    [191; 192) 'h': {unknown}
+    [195; 198) 'val': {unknown}
+    [215; 221) 'lambda': |u64, u64, i32| -> i32
+    [224; 256) '|a: u6...b; c }': |u64, u64, i32| -> i32
+    [225; 226) 'a': u64
+    [233; 234) 'b': u64
+    [236; 237) 'c': i32
+    [244; 256) '{ a + b; c }': i32
+    [246; 247) 'a': u64
+    [246; 251) 'a + b': u64
+    [250; 251) 'b': u64
+    [253; 254) 'c': i32
+    [267; 279) 'ref ref_to_x': &&i32
+    [282; 283) 'x': &i32
+    [293; 302) 'mut mut_x': &i32
+    [305; 306) 'x': &i32
+    [316; 336) 'ref mu...f_to_x': &mut &i32
+    [339; 340) 'x': &i32
+    [350; 351) 'k': &mut &i32
+    [354; 366) 'mut_ref_to_x': &mut &i32
+    "###
+    );
+}
+
+#[test]
+fn infer_pattern_match_ergonomics() {
+    assert_snapshot!(
+        infer(r#"
+struct A<T>(T);
+
+fn test() {
+    let A(n) = &A(1);
+    let A(n) = &mut A(1);
+}
+"#),
+    @r###"
+    [28; 79) '{     ...(1); }': ()
+    [38; 42) 'A(n)': A<i32>
+    [40; 41) 'n': &i32
+    [45; 50) '&A(1)': &A<i32>
+    [46; 47) 'A': A<i32>(T) -> A<T>
+    [46; 50) 'A(1)': A<i32>
+    [48; 49) '1': i32
+    [60; 64) 'A(n)': A<i32>
+    [62; 63) 'n': &mut i32
+    [67; 76) '&mut A(1)': &mut A<i32>
+    [72; 73) 'A': A<i32>(T) -> A<T>
+    [72; 76) 'A(1)': A<i32>
+    [74; 75) '1': i32
+    "###
+    );
+}
+
+#[test]
+fn infer_pattern_match_ergonomics_ref() {
+    covers!(match_ergonomics_ref);
+    assert_snapshot!(
+        infer(r#"
+fn test() {
+    let v = &(1, &2);
+    let (_, &w) = v;
+}
+"#),
+    @r###"
+    [11; 57) '{     ...= v; }': ()
+    [21; 22) 'v': &(i32, &i32)
+    [25; 33) '&(1, &2)': &(i32, &i32)
+    [26; 33) '(1, &2)': (i32, &i32)
+    [27; 28) '1': i32
+    [30; 32) '&2': &i32
+    [31; 32) '2': i32
+    [43; 50) '(_, &w)': (i32, &i32)
+    [44; 45) '_': i32
+    [47; 49) '&w': &i32
+    [48; 49) 'w': i32
+    [53; 54) 'v': &(i32, &i32)
+    "###
+    );
+}
+
+#[test]
+fn infer_adt_pattern() {
+    assert_snapshot!(
+        infer(r#"
+enum E {
+    A { x: usize },
+    B
+}
+
+struct S(u32, E);
+
+fn test() {
+    let e = E::A { x: 3 };
+
+    let S(y, z) = foo;
+    let E::A { x: new_var } = e;
+
+    match e {
+        E::A { x } => x,
+        E::B if foo => 1,
+        E::B => 10,
+    };
+
+    let ref d @ E::A { .. } = e;
+    d;
+}
+"#),
+        @r###"
+    [68; 289) '{     ...  d; }': ()
+    [78; 79) 'e': E
+    [82; 95) 'E::A { x: 3 }': E
+    [92; 93) '3': usize
+    [106; 113) 'S(y, z)': S
+    [108; 109) 'y': u32
+    [111; 112) 'z': E
+    [116; 119) 'foo': S
+    [129; 148) 'E::A {..._var }': E
+    [139; 146) 'new_var': usize
+    [151; 152) 'e': E
+    [159; 245) 'match ...     }': usize
+    [165; 166) 'e': E
+    [177; 187) 'E::A { x }': E
+    [184; 185) 'x': usize
+    [191; 192) 'x': usize
+    [202; 206) 'E::B': E
+    [210; 213) 'foo': bool
+    [217; 218) '1': usize
+    [228; 232) 'E::B': E
+    [236; 238) '10': usize
+    [256; 275) 'ref d ...{ .. }': &E
+    [264; 275) 'E::A { .. }': E
+    [278; 279) 'e': E
+    [285; 286) 'd': &E
+    "###
+    );
+}
+
+#[test]
+fn infer_struct_generics() {
+    assert_snapshot!(
+        infer(r#"
+struct A<T> {
+    x: T,
+}
+
+fn test(a1: A<u32>, i: i32) {
+    a1.x;
+    let a2 = A { x: i };
+    a2.x;
+    let a3 = A::<i128> { x: 1 };
+    a3.x;
+}
+"#),
+        @r###"
+    [36; 38) 'a1': A<u32>
+    [48; 49) 'i': i32
+    [56; 147) '{     ...3.x; }': ()
+    [62; 64) 'a1': A<u32>
+    [62; 66) 'a1.x': u32
+    [76; 78) 'a2': A<i32>
+    [81; 91) 'A { x: i }': A<i32>
+    [88; 89) 'i': i32
+    [97; 99) 'a2': A<i32>
+    [97; 101) 'a2.x': i32
+    [111; 113) 'a3': A<i128>
+    [116; 134) 'A::<i1...x: 1 }': A<i128>
+    [131; 132) '1': i128
+    [140; 142) 'a3': A<i128>
+    [140; 144) 'a3.x': i128
+    "###
+    );
+}
+
+#[test]
+fn infer_tuple_struct_generics() {
+    assert_snapshot!(
+        infer(r#"
+struct A<T>(T);
+enum Option<T> { Some(T), None }
+use Option::*;
+
+fn test() {
+    A(42);
+    A(42u128);
+    Some("x");
+    Option::Some("x");
+    None;
+    let x: Option<i64> = None;
+}
+"#),
+        @r###"
+    [76; 184) '{     ...one; }': ()
+    [82; 83) 'A': A<i32>(T) -> A<T>
+    [82; 87) 'A(42)': A<i32>
+    [84; 86) '42': i32
+    [93; 94) 'A': A<u128>(T) -> A<T>
+    [93; 102) 'A(42u128)': A<u128>
+    [95; 101) '42u128': u128
+    [108; 112) 'Some': Some<&str>(T) -> Option<T>
+    [108; 117) 'Some("x")': Option<&str>
+    [113; 116) '"x"': &str
+    [123; 135) 'Option::Some': Some<&str>(T) -> Option<T>
+    [123; 140) 'Option...e("x")': Option<&str>
+    [136; 139) '"x"': &str
+    [146; 150) 'None': Option<{unknown}>
+    [160; 161) 'x': Option<i64>
+    [177; 181) 'None': Option<i64>
+    "###
+    );
+}
+
+#[test]
+fn infer_generics_in_patterns() {
+    assert_snapshot!(
+        infer(r#"
+struct A<T> {
+    x: T,
+}
+
+enum Option<T> {
+    Some(T),
+    None,
+}
+
+fn test(a1: A<u32>, o: Option<u64>) {
+    let A { x: x2 } = a1;
+    let A::<i64> { x: x3 } = A { x: 1 };
+    match o {
+        Option::Some(t) => t,
+        _ => 1,
+    };
+}
+"#),
+        @r###"
+    [79; 81) 'a1': A<u32>
+    [91; 92) 'o': Option<u64>
+    [107; 244) '{     ...  }; }': ()
+    [117; 128) 'A { x: x2 }': A<u32>
+    [124; 126) 'x2': u32
+    [131; 133) 'a1': A<u32>
+    [143; 161) 'A::<i6...: x3 }': A<i64>
+    [157; 159) 'x3': i64
+    [164; 174) 'A { x: 1 }': A<i64>
+    [171; 172) '1': i64
+    [180; 241) 'match ...     }': u64
+    [186; 187) 'o': Option<u64>
+    [198; 213) 'Option::Some(t)': Option<u64>
+    [211; 212) 't': u64
+    [217; 218) 't': u64
+    [228; 229) '_': Option<u64>
+    [233; 234) '1': u64
+    "###
+    );
+}
+
+#[test]
+fn infer_function_generics() {
+    assert_snapshot!(
+        infer(r#"
+fn id<T>(t: T) -> T { t }
+
+fn test() {
+    id(1u32);
+    id::<i128>(1);
+    let x: u64 = id(1);
+}
+"#),
+        @r###"
+    [10; 11) 't': T
+    [21; 26) '{ t }': T
+    [23; 24) 't': T
+    [38; 98) '{     ...(1); }': ()
+    [44; 46) 'id': fn id<u32>(T) -> T
+    [44; 52) 'id(1u32)': u32
+    [47; 51) '1u32': u32
+    [58; 68) 'id::<i128>': fn id<i128>(T) -> T
+    [58; 71) 'id::<i128>(1)': i128
+    [69; 70) '1': i128
+    [81; 82) 'x': u64
+    [90; 92) 'id': fn id<u64>(T) -> T
+    [90; 95) 'id(1)': u64
+    [93; 94) '1': u64
+    "###
+    );
+}
+
+#[test]
+fn infer_impl_generics() {
+    assert_snapshot!(
+        infer(r#"
+struct A<T1, T2> {
+    x: T1,
+    y: T2,
+}
+impl<Y, X> A<X, Y> {
+    fn x(self) -> X {
+        self.x
+    }
+    fn y(self) -> Y {
+        self.y
+    }
+    fn z<T>(self, t: T) -> (X, Y, T) {
+        (self.x, self.y, t)
+    }
+}
+
+fn test() -> i128 {
+    let a = A { x: 1u64, y: 1i64 };
+    a.x();
+    a.y();
+    a.z(1i128);
+    a.z::<u128>(1);
+}
+"#),
+        @r###"
+    [74; 78) 'self': A<X, Y>
+    [85; 107) '{     ...     }': X
+    [95; 99) 'self': A<X, Y>
+    [95; 101) 'self.x': X
+    [117; 121) 'self': A<X, Y>
+    [128; 150) '{     ...     }': Y
+    [138; 142) 'self': A<X, Y>
+    [138; 144) 'self.y': Y
+    [163; 167) 'self': A<X, Y>
+    [169; 170) 't': T
+    [188; 223) '{     ...     }': (X, Y, T)
+    [198; 217) '(self.....y, t)': (X, Y, T)
+    [199; 203) 'self': A<X, Y>
+    [199; 205) 'self.x': X
+    [207; 211) 'self': A<X, Y>
+    [207; 213) 'self.y': Y
+    [215; 216) 't': T
+    [245; 342) '{     ...(1); }': ()
+    [255; 256) 'a': A<u64, i64>
+    [259; 281) 'A { x:...1i64 }': A<u64, i64>
+    [266; 270) '1u64': u64
+    [275; 279) '1i64': i64
+    [287; 288) 'a': A<u64, i64>
+    [287; 292) 'a.x()': u64
+    [298; 299) 'a': A<u64, i64>
+    [298; 303) 'a.y()': i64
+    [309; 310) 'a': A<u64, i64>
+    [309; 319) 'a.z(1i128)': (u64, i64, i128)
+    [313; 318) '1i128': i128
+    [325; 326) 'a': A<u64, i64>
+    [325; 339) 'a.z::<u128>(1)': (u64, i64, u128)
+    [337; 338) '1': u128
+    "###
+    );
+}
+
+#[test]
+fn infer_impl_generics_with_autoderef() {
+    assert_snapshot!(
+        infer(r#"
+enum Option<T> {
+    Some(T),
+    None,
+}
+impl<T> Option<T> {
+    fn as_ref(&self) -> Option<&T> {}
+}
+fn test(o: Option<u32>) {
+    (&o).as_ref();
+    o.as_ref();
+}
+"#),
+        @r###"
+    [78; 82) 'self': &Option<T>
+    [98; 100) '{}': ()
+    [111; 112) 'o': Option<u32>
+    [127; 165) '{     ...f(); }': ()
+    [133; 146) '(&o).as_ref()': Option<&u32>
+    [134; 136) '&o': &Option<u32>
+    [135; 136) 'o': Option<u32>
+    [152; 153) 'o': Option<u32>
+    [152; 162) 'o.as_ref()': Option<&u32>
+    "###
+    );
+}
+
+#[test]
+fn infer_generic_chain() {
+    assert_snapshot!(
+        infer(r#"
+struct A<T> {
+    x: T,
+}
+impl<T2> A<T2> {
+    fn x(self) -> T2 {
+        self.x
+    }
+}
+fn id<T>(t: T) -> T { t }
+
+fn test() -> i128 {
+     let x = 1;
+     let y = id(x);
+     let a = A { x: id(y) };
+     let z = id(a.x);
+     let b = A { x: z };
+     b.x()
+}
+"#),
+        @r###"
+    [53; 57) 'self': A<T2>
+    [65; 87) '{     ...     }': T2
+    [75; 79) 'self': A<T2>
+    [75; 81) 'self.x': T2
+    [99; 100) 't': T
+    [110; 115) '{ t }': T
+    [112; 113) 't': T
+    [135; 261) '{     ....x() }': i128
+    [146; 147) 'x': i128
+    [150; 151) '1': i128
+    [162; 163) 'y': i128
+    [166; 168) 'id': fn id<i128>(T) -> T
+    [166; 171) 'id(x)': i128
+    [169; 170) 'x': i128
+    [182; 183) 'a': A<i128>
+    [186; 200) 'A { x: id(y) }': A<i128>
+    [193; 195) 'id': fn id<i128>(T) -> T
+    [193; 198) 'id(y)': i128
+    [196; 197) 'y': i128
+    [211; 212) 'z': i128
+    [215; 217) 'id': fn id<i128>(T) -> T
+    [215; 222) 'id(a.x)': i128
+    [218; 219) 'a': A<i128>
+    [218; 221) 'a.x': i128
+    [233; 234) 'b': A<i128>
+    [237; 247) 'A { x: z }': A<i128>
+    [244; 245) 'z': i128
+    [254; 255) 'b': A<i128>
+    [254; 259) 'b.x()': i128
+    "###
+    );
+}
+
+#[test]
+fn infer_associated_const() {
+    assert_snapshot!(
+        infer(r#"
+struct Struct;
+
+impl Struct {
+    const FOO: u32 = 1;
+}
+
+enum Enum {}
+
+impl Enum {
+    const BAR: u32 = 2;
+}
+
+trait Trait {
+    const ID: u32;
+}
+
+struct TraitTest;
+
+impl Trait for TraitTest {
+    const ID: u32 = 5;
+}
+
+fn test() {
+    let x = Struct::FOO;
+    let y = Enum::BAR;
+    let z = TraitTest::ID;
+}
+"#),
+        @r###"
+    [52; 53) '1': u32
+    [105; 106) '2': u32
+    [213; 214) '5': u32
+    [229; 307) '{     ...:ID; }': ()
+    [239; 240) 'x': u32
+    [243; 254) 'Struct::FOO': u32
+    [264; 265) 'y': u32
+    [268; 277) 'Enum::BAR': u32
+    [287; 288) 'z': u32
+    [291; 304) 'TraitTest::ID': u32
+    "###
+    );
+}
+
+#[test]
+fn infer_associated_method_struct() {
+    assert_snapshot!(
+        infer(r#"
+struct A { x: u32 }
+
+impl A {
+    fn new() -> A {
+        A { x: 0 }
+    }
+}
+fn test() {
+    let a = A::new();
+    a.x;
+}
+"#),
+        @r###"
+    [49; 75) '{     ...     }': A
+    [59; 69) 'A { x: 0 }': A
+    [66; 67) '0': u32
+    [88; 122) '{     ...a.x; }': ()
+    [98; 99) 'a': A
+    [102; 108) 'A::new': fn new() -> A
+    [102; 110) 'A::new()': A
+    [116; 117) 'a': A
+    [116; 119) 'a.x': u32
+    "###
+    );
+}
+
+#[test]
+fn infer_associated_method_enum() {
+    assert_snapshot!(
+        infer(r#"
+enum A { B, C }
+
+impl A {
+    pub fn b() -> A {
+        A::B
+    }
+    pub fn c() -> A {
+        A::C
+    }
+}
+fn test() {
+    let a = A::b();
+    a;
+    let c = A::c();
+    c;
+}
+"#),
+        @r###"
+    [47; 67) '{     ...     }': A
+    [57; 61) 'A::B': A
+    [88; 108) '{     ...     }': A
+    [98; 102) 'A::C': A
+    [121; 178) '{     ...  c; }': ()
+    [131; 132) 'a': A
+    [135; 139) 'A::b': fn b() -> A
+    [135; 141) 'A::b()': A
+    [147; 148) 'a': A
+    [158; 159) 'c': A
+    [162; 166) 'A::c': fn c() -> A
+    [162; 168) 'A::c()': A
+    [174; 175) 'c': A
+    "###
+    );
+}
+
+#[test]
+fn infer_associated_method_with_modules() {
+    assert_snapshot!(
+        infer(r#"
+mod a {
+    struct A;
+    impl A { pub fn thing() -> A { A {} }}
+}
+
+mod b {
+    struct B;
+    impl B { pub fn thing() -> u32 { 99 }}
+
+    mod c {
+        struct C;
+        impl C { pub fn thing() -> C { C {} }}
+    }
+}
+use b::c;
+
+fn test() {
+    let x = a::A::thing();
+    let y = b::B::thing();
+    let z = c::C::thing();
+}
+"#),
+        @r###"
+    [56; 64) '{ A {} }': A
+    [58; 62) 'A {}': A
+    [126; 132) '{ 99 }': u32
+    [128; 130) '99': u32
+    [202; 210) '{ C {} }': C
+    [204; 208) 'C {}': C
+    [241; 325) '{     ...g(); }': ()
+    [251; 252) 'x': A
+    [255; 266) 'a::A::thing': fn thing() -> A
+    [255; 268) 'a::A::thing()': A
+    [278; 279) 'y': u32
+    [282; 293) 'b::B::thing': fn thing() -> u32
+    [282; 295) 'b::B::thing()': u32
+    [305; 306) 'z': C
+    [309; 320) 'c::C::thing': fn thing() -> C
+    [309; 322) 'c::C::thing()': C
+    "###
+    );
+}
+
+#[test]
+fn infer_associated_method_generics() {
+    assert_snapshot!(
+        infer(r#"
+struct Gen<T> {
+    val: T
+}
+
+impl<T> Gen<T> {
+    pub fn make(val: T) -> Gen<T> {
+        Gen { val }
+    }
+}
+
+fn test() {
+    let a = Gen::make(0u32);
+}
+"#),
+        @r###"
+    [64; 67) 'val': T
+    [82; 109) '{     ...     }': Gen<T>
+    [92; 103) 'Gen { val }': Gen<T>
+    [98; 101) 'val': T
+    [123; 155) '{     ...32); }': ()
+    [133; 134) 'a': Gen<u32>
+    [137; 146) 'Gen::make': fn make<u32>(T) -> Gen<T>
+    [137; 152) 'Gen::make(0u32)': Gen<u32>
+    [147; 151) '0u32': u32
+    "###
+    );
+}
+
+#[test]
+fn infer_associated_method_generics_with_default_param() {
+    assert_snapshot!(
+        infer(r#"
+struct Gen<T=u32> {
+    val: T
+}
+
+impl<T> Gen<T> {
+    pub fn make() -> Gen<T> {
+        loop { }
+    }
+}
+
+fn test() {
+    let a = Gen::make();
+}
+"#),
+        @r###"
+    [80; 104) '{     ...     }': Gen<T>
+    [90; 98) 'loop { }': !
+    [95; 98) '{ }': ()
+    [118; 146) '{     ...e(); }': ()
+    [128; 129) 'a': Gen<u32>
+    [132; 141) 'Gen::make': fn make<u32>() -> Gen<T>
+    [132; 143) 'Gen::make()': Gen<u32>
+    "###
+    );
+}
+
+#[test]
+fn infer_associated_method_generics_with_default_tuple_param() {
+    let t = type_at(
+        r#"
+//- /main.rs
+struct Gen<T=()> {
+    val: T
+}
+
+impl<T> Gen<T> {
+    pub fn make() -> Gen<T> {
+        loop { }
+    }
+}
+
+fn test() {
+    let a = Gen::make();
+    a.val<|>;
+}
+"#,
+    );
+    assert_eq!(t, "()");
+}
+
+#[test]
+fn infer_associated_method_generics_without_args() {
+    assert_snapshot!(
+        infer(r#"
+struct Gen<T> {
+    val: T
+}
+
+impl<T> Gen<T> {
+    pub fn make() -> Gen<T> {
+        loop { }
+    }
+}
+
+fn test() {
+    let a = Gen::<u32>::make();
+}
+"#),
+        @r###"
+    [76; 100) '{     ...     }': Gen<T>
+    [86; 94) 'loop { }': !
+    [91; 94) '{ }': ()
+    [114; 149) '{     ...e(); }': ()
+    [124; 125) 'a': Gen<u32>
+    [128; 144) 'Gen::<...::make': fn make<u32>() -> Gen<T>
+    [128; 146) 'Gen::<...make()': Gen<u32>
+    "###
+    );
+}
+
+#[test]
+fn infer_associated_method_generics_2_type_params_without_args() {
+    assert_snapshot!(
+        infer(r#"
+struct Gen<T, U> {
+    val: T,
+    val2: U,
+}
+
+impl<T> Gen<u32, T> {
+    pub fn make() -> Gen<u32,T> {
+        loop { }
+    }
+}
+
+fn test() {
+    let a = Gen::<u32, u64>::make();
+}
+"#),
+        @r###"
+    [102; 126) '{     ...     }': Gen<u32, T>
+    [112; 120) 'loop { }': !
+    [117; 120) '{ }': ()
+    [140; 180) '{     ...e(); }': ()
+    [150; 151) 'a': Gen<u32, u64>
+    [154; 175) 'Gen::<...::make': fn make<u64>() -> Gen<u32, T>
+    [154; 177) 'Gen::<...make()': Gen<u32, u64>
+    "###
+    );
+}
+
+#[test]
+fn infer_type_alias() {
+    assert_snapshot!(
+        infer(r#"
+struct A<X, Y> { x: X, y: Y }
+type Foo = A<u32, i128>;
+type Bar<T> = A<T, u128>;
+type Baz<U, V> = A<V, U>;
+fn test(x: Foo, y: Bar<&str>, z: Baz<i8, u8>) {
+    x.x;
+    x.y;
+    y.x;
+    y.y;
+    z.x;
+    z.y;
+}
+"#),
+        @r###"
+    [116; 117) 'x': A<u32, i128>
+    [124; 125) 'y': A<&str, u128>
+    [138; 139) 'z': A<u8, i8>
+    [154; 211) '{     ...z.y; }': ()
+    [160; 161) 'x': A<u32, i128>
+    [160; 163) 'x.x': u32
+    [169; 170) 'x': A<u32, i128>
+    [169; 172) 'x.y': i128
+    [178; 179) 'y': A<&str, u128>
+    [178; 181) 'y.x': &str
+    [187; 188) 'y': A<&str, u128>
+    [187; 190) 'y.y': u128
+    [196; 197) 'z': A<u8, i8>
+    [196; 199) 'z.x': u8
+    [205; 206) 'z': A<u8, i8>
+    [205; 208) 'z.y': i8
+    "###
+    )
+}
+
+#[test]
+#[should_panic] // we currently can't handle this
+fn recursive_type_alias() {
+    assert_snapshot!(
+        infer(r#"
+struct A<X> {}
+type Foo = Foo;
+type Bar = A<Bar>;
+fn test(x: Foo) {}
+"#),
+        @""
+    )
+}
+
+#[test]
+fn no_panic_on_field_of_enum() {
+    assert_snapshot!(
+        infer(r#"
+enum X {}
+
+fn test(x: X) {
+    x.some_field;
+}
+"#),
+        @r###"
+    [20; 21) 'x': X
+    [26; 47) '{     ...eld; }': ()
+    [32; 33) 'x': X
+    [32; 44) 'x.some_field': {unknown}
+    "###
+    );
+}
+
+#[test]
+fn bug_585() {
+    assert_snapshot!(
+        infer(r#"
+fn test() {
+    X {};
+    match x {
+        A::B {} => (),
+        A::Y() => (),
+    }
+}
+"#),
+        @r###"
+    [11; 89) '{     ...   } }': ()
+    [17; 21) 'X {}': {unknown}
+    [27; 87) 'match ...     }': ()
+    [33; 34) 'x': {unknown}
+    [45; 52) 'A::B {}': {unknown}
+    [56; 58) '()': ()
+    [68; 74) 'A::Y()': {unknown}
+    [78; 80) '()': ()
+    "###
+    );
+}
+
+#[test]
+fn bug_651() {
+    assert_snapshot!(
+        infer(r#"
+fn quux() {
+    let y = 92;
+    1 + y;
+}
+"#),
+        @r###"
+    [11; 41) '{     ...+ y; }': ()
+    [21; 22) 'y': i32
+    [25; 27) '92': i32
+    [33; 34) '1': i32
+    [33; 38) '1 + y': i32
+    [37; 38) 'y': i32
+    "###
+    );
+}
+
+#[test]
+fn recursive_vars() {
+    covers!(type_var_cycles_resolve_completely);
+    covers!(type_var_cycles_resolve_as_possible);
+    assert_snapshot!(
+        infer(r#"
+fn test() {
+    let y = unknown;
+    [y, &y];
+}
+"#),
+        @r###"
+    [11; 48) '{     ...&y]; }': ()
+    [21; 22) 'y': &{unknown}
+    [25; 32) 'unknown': &{unknown}
+    [38; 45) '[y, &y]': [&&{unknown};_]
+    [39; 40) 'y': &{unknown}
+    [42; 44) '&y': &&{unknown}
+    [43; 44) 'y': &{unknown}
+    "###
+    );
+}
+
+#[test]
+fn recursive_vars_2() {
+    covers!(type_var_cycles_resolve_completely);
+    covers!(type_var_cycles_resolve_as_possible);
+    assert_snapshot!(
+        infer(r#"
+fn test() {
+    let x = unknown;
+    let y = unknown;
+    [(x, y), (&y, &x)];
+}
+"#),
+        @r###"
+    [11; 80) '{     ...x)]; }': ()
+    [21; 22) 'x': &&{unknown}
+    [25; 32) 'unknown': &&{unknown}
+    [42; 43) 'y': &&{unknown}
+    [46; 53) 'unknown': &&{unknown}
+    [59; 77) '[(x, y..., &x)]': [(&&&{unknown}, &&&{unknown});_]
+    [60; 66) '(x, y)': (&&&{unknown}, &&&{unknown})
+    [61; 62) 'x': &&{unknown}
+    [64; 65) 'y': &&{unknown}
+    [68; 76) '(&y, &x)': (&&&{unknown}, &&&{unknown})
+    [69; 71) '&y': &&&{unknown}
+    [70; 71) 'y': &&{unknown}
+    [73; 75) '&x': &&&{unknown}
+    [74; 75) 'x': &&{unknown}
+    "###
+    );
+}
+
+#[test]
+fn infer_type_param() {
+    assert_snapshot!(
+        infer(r#"
+fn id<T>(x: T) -> T {
+    x
+}
+
+fn clone<T>(x: &T) -> T {
+    *x
+}
+
+fn test() {
+    let y = 10u32;
+    id(y);
+    let x: bool = clone(z);
+    id::<i128>(1);
+}
+"#),
+        @r###"
+    [10; 11) 'x': T
+    [21; 30) '{     x }': T
+    [27; 28) 'x': T
+    [44; 45) 'x': &T
+    [56; 66) '{     *x }': T
+    [62; 64) '*x': T
+    [63; 64) 'x': &T
+    [78; 158) '{     ...(1); }': ()
+    [88; 89) 'y': u32
+    [92; 97) '10u32': u32
+    [103; 105) 'id': fn id<u32>(T) -> T
+    [103; 108) 'id(y)': u32
+    [106; 107) 'y': u32
+    [118; 119) 'x': bool
+    [128; 133) 'clone': fn clone<bool>(&T) -> T
+    [128; 136) 'clone(z)': bool
+    [134; 135) 'z': &bool
+    [142; 152) 'id::<i128>': fn id<i128>(T) -> T
+    [142; 155) 'id::<i128>(1)': i128
+    [153; 154) '1': i128
+    "###
+    );
+}
+
+#[test]
+fn infer_std_crash_1() {
+    // caused stack overflow, taken from std
+    assert_snapshot!(
+        infer(r#"
+enum Maybe<T> {
+    Real(T),
+    Fake,
+}
+
+fn write() {
+    match something_unknown {
+        Maybe::Real(ref mut something) => (),
+    }
+}
+"#),
+        @r###"
+    [54; 139) '{     ...   } }': ()
+    [60; 137) 'match ...     }': ()
+    [66; 83) 'someth...nknown': Maybe<{unknown}>
+    [94; 124) 'Maybe:...thing)': Maybe<{unknown}>
+    [106; 123) 'ref mu...ething': &mut {unknown}
+    [128; 130) '()': ()
+    "###
+    );
+}
+
+#[test]
+fn infer_std_crash_2() {
+    covers!(type_var_resolves_to_int_var);
+    // caused "equating two type variables, ...", taken from std
+    assert_snapshot!(
+        infer(r#"
+fn test_line_buffer() {
+    &[0, b'\n', 1, b'\n'];
+}
+"#),
+        @r###"
+    [23; 53) '{     ...n']; }': ()
+    [29; 50) '&[0, b...b'\n']': &[u8;_]
+    [30; 50) '[0, b'...b'\n']': [u8;_]
+    [31; 32) '0': u8
+    [34; 39) 'b'\n'': u8
+    [41; 42) '1': u8
+    [44; 49) 'b'\n'': u8
+    "###
+    );
+}
+
+#[test]
+fn infer_std_crash_3() {
+    // taken from rustc
+    assert_snapshot!(
+        infer(r#"
+pub fn compute() {
+    match nope!() {
+        SizeSkeleton::Pointer { non_zero: true, tail } => {}
+    }
+}
+"#),
+        @r###"
+    [18; 108) '{     ...   } }': ()
+    [24; 106) 'match ...     }': ()
+    [30; 37) 'nope!()': {unknown}
+    [48; 94) 'SizeSk...tail }': {unknown}
+    [82; 86) 'true': {unknown}
+    [88; 92) 'tail': {unknown}
+    [98; 100) '{}': ()
+    "###
+    );
+}
+
+#[test]
+fn infer_std_crash_4() {
+    // taken from rustc
+    assert_snapshot!(
+        infer(r#"
+pub fn primitive_type() {
+    match *self {
+        BorrowedRef { type_: Primitive(p), ..} => {},
+    }
+}
+"#),
+        @r###"
+    [25; 106) '{     ...   } }': ()
+    [31; 104) 'match ...     }': ()
+    [37; 42) '*self': {unknown}
+    [38; 42) 'self': {unknown}
+    [53; 91) 'Borrow...), ..}': {unknown}
+    [74; 86) 'Primitive(p)': {unknown}
+    [84; 85) 'p': {unknown}
+    [95; 97) '{}': ()
+    "###
+    );
+}
+
+#[test]
+fn infer_std_crash_5() {
+    // taken from rustc
+    assert_snapshot!(
+        infer(r#"
+fn extra_compiler_flags() {
+    for content in doesnt_matter {
+        let name = if doesnt_matter {
+            first
+        } else {
+            &content
+        };
+
+        let content = if ICE_REPORT_COMPILER_FLAGS_STRIP_VALUE.contains(&name) {
+            name
+        } else {
+            content
+        };
+    }
+}
+"#),
+        @r###"
+    [27; 323) '{     ...   } }': ()
+    [33; 321) 'for co...     }': ()
+    [37; 44) 'content': &{unknown}
+    [48; 61) 'doesnt_matter': {unknown}
+    [62; 321) '{     ...     }': ()
+    [76; 80) 'name': &&{unknown}
+    [83; 167) 'if doe...     }': &&{unknown}
+    [86; 99) 'doesnt_matter': bool
+    [100; 129) '{     ...     }': &&{unknown}
+    [114; 119) 'first': &&{unknown}
+    [135; 167) '{     ...     }': &&{unknown}
+    [149; 157) '&content': &&{unknown}
+    [150; 157) 'content': &{unknown}
+    [182; 189) 'content': &{unknown}
+    [192; 314) 'if ICE...     }': &{unknown}
+    [195; 232) 'ICE_RE..._VALUE': {unknown}
+    [195; 248) 'ICE_RE...&name)': bool
+    [242; 247) '&name': &&&{unknown}
+    [243; 247) 'name': &&{unknown}
+    [249; 277) '{     ...     }': &&{unknown}
+    [263; 267) 'name': &&{unknown}
+    [283; 314) '{     ...     }': &{unknown}
+    [297; 304) 'content': &{unknown}
+    "###
+    );
+}
+
+#[test]
+fn infer_nested_generics_crash() {
+    // another crash found typechecking rustc
+    assert_snapshot!(
+        infer(r#"
+struct Canonical<V> {
+    value: V,
+}
+struct QueryResponse<V> {
+    value: V,
+}
+fn test<R>(query_response: Canonical<QueryResponse<R>>) {
+    &query_response.value;
+}
+"#),
+        @r###"
+    [92; 106) 'query_response': Canonical<QueryResponse<R>>
+    [137; 167) '{     ...lue; }': ()
+    [143; 164) '&query....value': &QueryResponse<R>
+    [144; 158) 'query_response': Canonical<QueryResponse<R>>
+    [144; 164) 'query_....value': QueryResponse<R>
+    "###
+    );
+}
+
+#[test]
+fn bug_1030() {
+    assert_snapshot!(infer(r#"
+struct HashSet<T, H>;
+struct FxHasher;
+type FxHashSet<T> = HashSet<T, FxHasher>;
+
+impl<T, H> HashSet<T, H> {
+    fn default() -> HashSet<T, H> {}
+}
+
+pub fn main_loop() {
+    FxHashSet::default();
+}
+"#),
+    @r###"
+    [144; 146) '{}': ()
+    [169; 198) '{     ...t(); }': ()
+    [175; 193) 'FxHash...efault': fn default<{unknown}, FxHasher>() -> HashSet<T, H>
+    [175; 195) 'FxHash...ault()': HashSet<{unknown}, FxHasher>
+    "###
+    );
+}
+
+#[test]
+fn cross_crate_associated_method_call() {
+    let (db, pos) = TestDB::with_position(
+        r#"
+//- /main.rs crate:main deps:other_crate
+fn test() {
+    let x = other_crate::foo::S::thing();
+    x<|>;
+}
+
+//- /lib.rs crate:other_crate
+mod foo {
+    struct S;
+    impl S {
+        fn thing() -> i128 {}
+    }
+}
+"#,
+    );
+    assert_eq!("i128", type_at_pos(&db, pos));
+}
+
+#[test]
+fn infer_const() {
+    assert_snapshot!(
+        infer(r#"
+struct Foo;
+impl Foo { const ASSOC_CONST: u32 = 0; }
+const GLOBAL_CONST: u32 = 101;
+fn test() {
+    const LOCAL_CONST: u32 = 99;
+    let x = LOCAL_CONST;
+    let z = GLOBAL_CONST;
+    let id = Foo::ASSOC_CONST;
+}
+"#),
+        @r###"
+    [49; 50) '0': u32
+    [80; 83) '101': u32
+    [95; 213) '{     ...NST; }': ()
+    [138; 139) 'x': {unknown}
+    [142; 153) 'LOCAL_CONST': {unknown}
+    [163; 164) 'z': u32
+    [167; 179) 'GLOBAL_CONST': u32
+    [189; 191) 'id': u32
+    [194; 210) 'Foo::A..._CONST': u32
+    "###
+    );
+}
+
+#[test]
+fn infer_static() {
+    assert_snapshot!(
+        infer(r#"
+static GLOBAL_STATIC: u32 = 101;
+static mut GLOBAL_STATIC_MUT: u32 = 101;
+fn test() {
+    static LOCAL_STATIC: u32 = 99;
+    static mut LOCAL_STATIC_MUT: u32 = 99;
+    let x = LOCAL_STATIC;
+    let y = LOCAL_STATIC_MUT;
+    let z = GLOBAL_STATIC;
+    let w = GLOBAL_STATIC_MUT;
+}
+"#),
+        @r###"
+    [29; 32) '101': u32
+    [70; 73) '101': u32
+    [85; 280) '{     ...MUT; }': ()
+    [173; 174) 'x': {unknown}
+    [177; 189) 'LOCAL_STATIC': {unknown}
+    [199; 200) 'y': {unknown}
+    [203; 219) 'LOCAL_...IC_MUT': {unknown}
+    [229; 230) 'z': u32
+    [233; 246) 'GLOBAL_STATIC': u32
+    [256; 257) 'w': u32
+    [260; 277) 'GLOBAL...IC_MUT': u32
+    "###
+    );
+}
+
+#[test]
+fn infer_trait_method_simple() {
+    // the trait implementation is intentionally incomplete -- it shouldn't matter
+    assert_snapshot!(
+        infer(r#"
+trait Trait1 {
+    fn method(&self) -> u32;
+}
+struct S1;
+impl Trait1 for S1 {}
+trait Trait2 {
+    fn method(&self) -> i128;
+}
+struct S2;
+impl Trait2 for S2 {}
+fn test() {
+    S1.method(); // -> u32
+    S2.method(); // -> i128
+}
+"#),
+        @r###"
+    [31; 35) 'self': &Self
+    [110; 114) 'self': &Self
+    [170; 228) '{     ...i128 }': ()
+    [176; 178) 'S1': S1
+    [176; 187) 'S1.method()': u32
+    [203; 205) 'S2': S2
+    [203; 214) 'S2.method()': i128
+    "###
+    );
+}
+
+#[test]
+fn infer_trait_method_scoped() {
+    // the trait implementation is intentionally incomplete -- it shouldn't matter
+    assert_snapshot!(
+        infer(r#"
+struct S;
+mod foo {
+    pub trait Trait1 {
+        fn method(&self) -> u32;
+    }
+    impl Trait1 for super::S {}
+}
+mod bar {
+    pub trait Trait2 {
+        fn method(&self) -> i128;
+    }
+    impl Trait2 for super::S {}
+}
+
+mod foo_test {
+    use super::S;
+    use super::foo::Trait1;
+    fn test() {
+        S.method(); // -> u32
+    }
+}
+
+mod bar_test {
+    use super::S;
+    use super::bar::Trait2;
+    fn test() {
+        S.method(); // -> i128
+    }
+}
+"#),
+        @r###"
+    [63; 67) 'self': &Self
+    [169; 173) 'self': &Self
+    [300; 337) '{     ...     }': ()
+    [310; 311) 'S': S
+    [310; 320) 'S.method()': u32
+    [416; 454) '{     ...     }': ()
+    [426; 427) 'S': S
+    [426; 436) 'S.method()': i128
+    "###
+    );
+}
+
+#[test]
+fn infer_trait_method_generic_1() {
+    // the trait implementation is intentionally incomplete -- it shouldn't matter
+    assert_snapshot!(
+        infer(r#"
+trait Trait<T> {
+    fn method(&self) -> T;
+}
+struct S;
+impl Trait<u32> for S {}
+fn test() {
+    S.method();
+}
+"#),
+        @r###"
+    [33; 37) 'self': &Self
+    [92; 111) '{     ...d(); }': ()
+    [98; 99) 'S': S
+    [98; 108) 'S.method()': u32
+    "###
+    );
+}
+
+#[test]
+fn infer_trait_method_generic_more_params() {
+    // the trait implementation is intentionally incomplete -- it shouldn't matter
+    assert_snapshot!(
+        infer(r#"
+trait Trait<T1, T2, T3> {
+    fn method1(&self) -> (T1, T2, T3);
+    fn method2(&self) -> (T3, T2, T1);
+}
+struct S1;
+impl Trait<u8, u16, u32> for S1 {}
+struct S2;
+impl<T> Trait<i8, i16, T> for S2 {}
+fn test() {
+    S1.method1(); // u8, u16, u32
+    S1.method2(); // u32, u16, u8
+    S2.method1(); // i8, i16, {unknown}
+    S2.method2(); // {unknown}, i16, i8
+}
+"#),
+        @r###"
+    [43; 47) 'self': &Self
+    [82; 86) 'self': &Self
+    [210; 361) '{     ..., i8 }': ()
+    [216; 218) 'S1': S1
+    [216; 228) 'S1.method1()': (u8, u16, u32)
+    [250; 252) 'S1': S1
+    [250; 262) 'S1.method2()': (u32, u16, u8)
+    [284; 286) 'S2': S2
+    [284; 296) 'S2.method1()': (i8, i16, {unknown})
+    [324; 326) 'S2': S2
+    [324; 336) 'S2.method2()': ({unknown}, i16, i8)
+    "###
+    );
+}
+
+#[test]
+fn infer_trait_method_generic_2() {
+    // the trait implementation is intentionally incomplete -- it shouldn't matter
+    assert_snapshot!(
+        infer(r#"
+trait Trait<T> {
+    fn method(&self) -> T;
+}
+struct S<T>(T);
+impl<U> Trait<U> for S<U> {}
+fn test() {
+    S(1u32).method();
+}
+"#),
+        @r###"
+    [33; 37) 'self': &Self
+    [102; 127) '{     ...d(); }': ()
+    [108; 109) 'S': S<u32>(T) -> S<T>
+    [108; 115) 'S(1u32)': S<u32>
+    [108; 124) 'S(1u32...thod()': u32
+    [110; 114) '1u32': u32
+    "###
+    );
+}
+
+#[test]
+fn infer_trait_assoc_method() {
+    assert_snapshot!(
+        infer(r#"
+trait Default {
+    fn default() -> Self;
+}
+struct S;
+impl Default for S {}
+fn test() {
+    let s1: S = Default::default();
+    let s2 = S::default();
+    let s3 = <S as Default>::default();
+}
+"#),
+        @r###"
+    [87; 193) '{     ...t(); }': ()
+    [97; 99) 's1': S
+    [105; 121) 'Defaul...efault': fn default<S>() -> Self
+    [105; 123) 'Defaul...ault()': S
+    [133; 135) 's2': S
+    [138; 148) 'S::default': fn default<S>() -> Self
+    [138; 150) 'S::default()': S
+    [160; 162) 's3': S
+    [165; 188) '<S as ...efault': fn default<S>() -> Self
+    [165; 190) '<S as ...ault()': S
+    "###
+    );
+}
+
+#[test]
+fn infer_trait_assoc_method_generics_1() {
+    assert_snapshot!(
+        infer(r#"
+trait Trait<T> {
+    fn make() -> T;
+}
+struct S;
+impl Trait<u32> for S {}
+struct G<T>;
+impl<T> Trait<T> for G<T> {}
+fn test() {
+    let a = S::make();
+    let b = G::<u64>::make();
+    let c: f64 = G::make();
+}
+"#),
+        @r###"
+    [127; 211) '{     ...e(); }': ()
+    [137; 138) 'a': u32
+    [141; 148) 'S::make': fn make<S, u32>() -> T
+    [141; 150) 'S::make()': u32
+    [160; 161) 'b': u64
+    [164; 178) 'G::<u64>::make': fn make<G<u64>, u64>() -> T
+    [164; 180) 'G::<u6...make()': u64
+    [190; 191) 'c': f64
+    [199; 206) 'G::make': fn make<G<f64>, f64>() -> T
+    [199; 208) 'G::make()': f64
+    "###
+    );
+}
+
+#[test]
+fn infer_trait_assoc_method_generics_2() {
+    assert_snapshot!(
+        infer(r#"
+trait Trait<T> {
+    fn make<U>() -> (T, U);
+}
+struct S;
+impl Trait<u32> for S {}
+struct G<T>;
+impl<T> Trait<T> for G<T> {}
+fn test() {
+    let a = S::make::<i64>();
+    let b: (_, i64) = S::make();
+    let c = G::<u32>::make::<i64>();
+    let d: (u32, _) = G::make::<i64>();
+    let e: (u32, i64) = G::make();
+}
+"#),
+        @r###"
+    [135; 313) '{     ...e(); }': ()
+    [145; 146) 'a': (u32, i64)
+    [149; 163) 'S::make::<i64>': fn make<S, u32, i64>() -> (T, U)
+    [149; 165) 'S::mak...i64>()': (u32, i64)
+    [175; 176) 'b': (u32, i64)
+    [189; 196) 'S::make': fn make<S, u32, i64>() -> (T, U)
+    [189; 198) 'S::make()': (u32, i64)
+    [208; 209) 'c': (u32, i64)
+    [212; 233) 'G::<u3...:<i64>': fn make<G<u32>, u32, i64>() -> (T, U)
+    [212; 235) 'G::<u3...i64>()': (u32, i64)
+    [245; 246) 'd': (u32, i64)
+    [259; 273) 'G::make::<i64>': fn make<G<u32>, u32, i64>() -> (T, U)
+    [259; 275) 'G::mak...i64>()': (u32, i64)
+    [285; 286) 'e': (u32, i64)
+    [301; 308) 'G::make': fn make<G<u32>, u32, i64>() -> (T, U)
+    [301; 310) 'G::make()': (u32, i64)
+    "###
+    );
+}
+
+#[test]
+fn infer_trait_assoc_method_generics_3() {
+    assert_snapshot!(
+        infer(r#"
+trait Trait<T> {
+    fn make() -> (Self, T);
+}
+struct S<T>;
+impl Trait<i64> for S<i32> {}
+fn test() {
+    let a = S::make();
+}
+"#),
+        @r###"
+    [101; 127) '{     ...e(); }': ()
+    [111; 112) 'a': (S<i32>, i64)
+    [115; 122) 'S::make': fn make<S<i32>, i64>() -> (Self, T)
+    [115; 124) 'S::make()': (S<i32>, i64)
+    "###
+    );
+}
+
+#[test]
+fn infer_trait_assoc_method_generics_4() {
+    assert_snapshot!(
+        infer(r#"
+trait Trait<T> {
+    fn make() -> (Self, T);
+}
+struct S<T>;
+impl Trait<i64> for S<u64> {}
+impl Trait<i32> for S<u32> {}
+fn test() {
+    let a: (S<u64>, _) = S::make();
+    let b: (_, i32) = S::make();
+}
+"#),
+        @r###"
+    [131; 203) '{     ...e(); }': ()
+    [141; 142) 'a': (S<u64>, i64)
+    [158; 165) 'S::make': fn make<S<u64>, i64>() -> (Self, T)
+    [158; 167) 'S::make()': (S<u64>, i64)
+    [177; 178) 'b': (S<u32>, i32)
+    [191; 198) 'S::make': fn make<S<u32>, i32>() -> (Self, T)
+    [191; 200) 'S::make()': (S<u32>, i32)
+    "###
+    );
+}
+
+#[test]
+fn infer_trait_assoc_method_generics_5() {
+    assert_snapshot!(
+        infer(r#"
+trait Trait<T> {
+    fn make<U>() -> (Self, T, U);
+}
+struct S<T>;
+impl Trait<i64> for S<u64> {}
+fn test() {
+    let a = <S as Trait<i64>>::make::<u8>();
+    let b: (S<u64>, _, _) = Trait::<i64>::make::<u8>();
+}
+"#),
+        @r###"
+    [107; 211) '{     ...>(); }': ()
+    [117; 118) 'a': (S<u64>, i64, u8)
+    [121; 150) '<S as ...::<u8>': fn make<S<u64>, i64, u8>() -> (Self, T, U)
+    [121; 152) '<S as ...<u8>()': (S<u64>, i64, u8)
+    [162; 163) 'b': (S<u64>, i64, u8)
+    [182; 206) 'Trait:...::<u8>': fn make<S<u64>, i64, u8>() -> (Self, T, U)
+    [182; 208) 'Trait:...<u8>()': (S<u64>, i64, u8)
+    "###
+    );
+}
+
+#[test]
+fn infer_from_bound_1() {
+    assert_snapshot!(
+        infer(r#"
+trait Trait<T> {}
+struct S<T>(T);
+impl<U> Trait<U> for S<U> {}
+fn foo<T: Trait<u32>>(t: T) {}
+fn test() {
+    let s = S(unknown);
+    foo(s);
+}
+"#),
+        @r###"
+    [86; 87) 't': T
+    [92; 94) '{}': ()
+    [105; 144) '{     ...(s); }': ()
+    [115; 116) 's': S<u32>
+    [119; 120) 'S': S<u32>(T) -> S<T>
+    [119; 129) 'S(unknown)': S<u32>
+    [121; 128) 'unknown': u32
+    [135; 138) 'foo': fn foo<S<u32>>(T) -> ()
+    [135; 141) 'foo(s)': ()
+    [139; 140) 's': S<u32>
+    "###
+    );
+}
+
+#[test]
+fn infer_from_bound_2() {
+    assert_snapshot!(
+        infer(r#"
+trait Trait<T> {}
+struct S<T>(T);
+impl<U> Trait<U> for S<U> {}
+fn foo<U, T: Trait<U>>(t: T) -> U {}
+fn test() {
+    let s = S(unknown);
+    let x: u32 = foo(s);
+}
+"#),
+        @r###"
+    [87; 88) 't': T
+    [98; 100) '{}': ()
+    [111; 163) '{     ...(s); }': ()
+    [121; 122) 's': S<u32>
+    [125; 126) 'S': S<u32>(T) -> S<T>
+    [125; 135) 'S(unknown)': S<u32>
+    [127; 134) 'unknown': u32
+    [145; 146) 'x': u32
+    [154; 157) 'foo': fn foo<u32, S<u32>>(T) -> U
+    [154; 160) 'foo(s)': u32
+    [158; 159) 's': S<u32>
+    "###
+    );
+}
+
+#[test]
+fn infer_call_trait_method_on_generic_param_1() {
+    assert_snapshot!(
+        infer(r#"
+trait Trait {
+    fn method(&self) -> u32;
+}
+fn test<T: Trait>(t: T) {
+    t.method();
+}
+"#),
+        @r###"
+    [30; 34) 'self': &Self
+    [64; 65) 't': T
+    [70; 89) '{     ...d(); }': ()
+    [76; 77) 't': T
+    [76; 86) 't.method()': u32
+    "###
+    );
+}
+
+#[test]
+fn infer_call_trait_method_on_generic_param_2() {
+    assert_snapshot!(
+        infer(r#"
+trait Trait<T> {
+    fn method(&self) -> T;
+}
+fn test<U, T: Trait<U>>(t: T) {
+    t.method();
+}
+"#),
+        @r###"
+    [33; 37) 'self': &Self
+    [71; 72) 't': T
+    [77; 96) '{     ...d(); }': ()
+    [83; 84) 't': T
+    [83; 93) 't.method()': [missing name]
+    "###
+    );
+}
+
+#[test]
+fn infer_with_multiple_trait_impls() {
+    assert_snapshot!(
+        infer(r#"
+trait Into<T> {
+    fn into(self) -> T;
+}
+struct S;
+impl Into<u32> for S {}
+impl Into<u64> for S {}
+fn test() {
+    let x: u32 = S.into();
+    let y: u64 = S.into();
+    let z = Into::<u64>::into(S);
+}
+"#),
+        @r###"
+    [29; 33) 'self': Self
+    [111; 202) '{     ...(S); }': ()
+    [121; 122) 'x': u32
+    [130; 131) 'S': S
+    [130; 138) 'S.into()': u32
+    [148; 149) 'y': u64
+    [157; 158) 'S': S
+    [157; 165) 'S.into()': u64
+    [175; 176) 'z': u64
+    [179; 196) 'Into::...::into': fn into<S, u64>(Self) -> T
+    [179; 199) 'Into::...nto(S)': u64
+    [197; 198) 'S': S
+    "###
+    );
+}
+
+#[test]
+fn infer_project_associated_type() {
+    // y, z, a don't yet work because of https://github.com/rust-lang/chalk/issues/234
+    assert_snapshot!(
+        infer(r#"
+trait Iterable {
+   type Item;
+}
+struct S;
+impl Iterable for S { type Item = u32; }
+fn test<T: Iterable>() {
+    let x: <S as Iterable>::Item = 1;
+    let y: <T as Iterable>::Item = no_matter;
+    let z: T::Item = no_matter;
+    let a: <T>::Item = no_matter;
+}
+"#),
+        @r###"
+    [108; 261) '{     ...ter; }': ()
+    [118; 119) 'x': u32
+    [145; 146) '1': u32
+    [156; 157) 'y': {unknown}
+    [183; 192) 'no_matter': {unknown}
+    [202; 203) 'z': {unknown}
+    [215; 224) 'no_matter': {unknown}
+    [234; 235) 'a': {unknown}
+    [249; 258) 'no_matter': {unknown}
+    "###
+    );
+}
+
+#[test]
+fn infer_return_associated_type() {
+    assert_snapshot!(
+        infer(r#"
+trait Iterable {
+   type Item;
+}
+struct S;
+impl Iterable for S { type Item = u32; }
+fn foo1<T: Iterable>(t: T) -> T::Item {}
+fn foo2<T: Iterable>(t: T) -> <T as Iterable>::Item {}
+fn foo3<T: Iterable>(t: T) -> <T>::Item {}
+fn test() {
+    let x = foo1(S);
+    let y = foo2(S);
+    let z = foo3(S);
+}
+"#),
+        @r###"
+    [106; 107) 't': T
+    [123; 125) '{}': ()
+    [147; 148) 't': T
+    [178; 180) '{}': ()
+    [202; 203) 't': T
+    [221; 223) '{}': ()
+    [234; 300) '{     ...(S); }': ()
+    [244; 245) 'x': u32
+    [248; 252) 'foo1': fn foo1<S>(T) -> <T as Iterable>::Item
+    [248; 255) 'foo1(S)': u32
+    [253; 254) 'S': S
+    [265; 266) 'y': u32
+    [269; 273) 'foo2': fn foo2<S>(T) -> <T as Iterable>::Item
+    [269; 276) 'foo2(S)': u32
+    [274; 275) 'S': S
+    [286; 287) 'z': u32
+    [290; 294) 'foo3': fn foo3<S>(T) -> <T as Iterable>::Item
+    [290; 297) 'foo3(S)': u32
+    [295; 296) 'S': S
+    "###
+    );
+}
+
+#[test]
+fn infer_associated_type_bound() {
+    assert_snapshot!(
+        infer(r#"
+trait Iterable {
+   type Item;
+}
+fn test<T: Iterable<Item=u32>>() {
+    let y: T::Item = unknown;
+}
+"#),
+        @r###"
+    [67; 100) '{     ...own; }': ()
+    [77; 78) 'y': {unknown}
+    [90; 97) 'unknown': {unknown}
+    "###
+    );
+}
+
+#[test]
+fn infer_const_body() {
+    assert_snapshot!(
+        infer(r#"
+const A: u32 = 1 + 1;
+static B: u64 = { let x = 1; x };
+"#),
+        @r###"
+    [16; 17) '1': u32
+    [16; 21) '1 + 1': u32
+    [20; 21) '1': u32
+    [39; 55) '{ let ...1; x }': u64
+    [45; 46) 'x': u64
+    [49; 50) '1': u64
+    [52; 53) 'x': u64
+    "###
+    );
+}
+
+#[test]
+fn tuple_struct_fields() {
+    assert_snapshot!(
+        infer(r#"
+struct S(i32, u64);
+fn test() -> u64 {
+    let a = S(4, 6);
+    let b = a.0;
+    a.1
+}
+"#),
+        @r###"
+    [38; 87) '{     ... a.1 }': u64
+    [48; 49) 'a': S
+    [52; 53) 'S': S(i32, u64) -> S
+    [52; 59) 'S(4, 6)': S
+    [54; 55) '4': i32
+    [57; 58) '6': u64
+    [69; 70) 'b': i32
+    [73; 74) 'a': S
+    [73; 76) 'a.0': i32
+    [82; 83) 'a': S
+    [82; 85) 'a.1': u64
+    "###
+    );
+}
+
+#[test]
+fn tuple_struct_with_fn() {
+    assert_snapshot!(
+        infer(r#"
+struct S(fn(u32) -> u64);
+fn test() -> u64 {
+    let a = S(|i| 2*i);
+    let b = a.0(4);
+    a.0(2)
+}
+"#),
+        @r###"
+    [44; 102) '{     ...0(2) }': u64
+    [54; 55) 'a': S
+    [58; 59) 'S': S(fn(u32) -> u64) -> S
+    [58; 68) 'S(|i| 2*i)': S
+    [60; 67) '|i| 2*i': |i32| -> i32
+    [61; 62) 'i': i32
+    [64; 65) '2': i32
+    [64; 67) '2*i': i32
+    [66; 67) 'i': i32
+    [78; 79) 'b': u64
+    [82; 83) 'a': S
+    [82; 85) 'a.0': fn(u32) -> u64
+    [82; 88) 'a.0(4)': u64
+    [86; 87) '4': u32
+    [94; 95) 'a': S
+    [94; 97) 'a.0': fn(u32) -> u64
+    [94; 100) 'a.0(2)': u64
+    [98; 99) '2': u32
+    "###
+    );
+}
+
+#[test]
+fn indexing_arrays() {
+    assert_snapshot!(
+        infer("fn main() { &mut [9][2]; }"),
+        @r###"
+    [10; 26) '{ &mut...[2]; }': ()
+    [12; 23) '&mut [9][2]': &mut {unknown}
+    [17; 20) '[9]': [i32;_]
+    [17; 23) '[9][2]': {unknown}
+    [18; 19) '9': i32
+    [21; 22) '2': i32
+    "###
+    )
+}
+
+#[test]
+fn infer_macros_expanded() {
+    assert_snapshot!(
+        infer(r#"
+struct Foo(Vec<i32>);
+
+macro_rules! foo {
+    ($($item:expr),*) => {
+            {
+                Foo(vec![$($item,)*])
+            }
+    };
+}
+
+fn main() {
+    let x = foo!(1,2);
+}
+"#),
+        @r###"
+    ![0; 17) '{Foo(v...,2,])}': Foo
+    ![1; 4) 'Foo': Foo({unknown}) -> Foo
+    ![1; 16) 'Foo(vec![1,2,])': Foo
+    ![5; 15) 'vec![1,2,]': {unknown}
+    [156; 182) '{     ...,2); }': ()
+    [166; 167) 'x': Foo
+    "###
+    );
+}
+
+#[test]
+fn infer_legacy_textual_scoped_macros_expanded() {
+    assert_snapshot!(
+        infer(r#"
+struct Foo(Vec<i32>);
+
+#[macro_use]
+mod m {
+    macro_rules! foo {
+        ($($item:expr),*) => {
+            {
+                Foo(vec![$($item,)*])
+            }
+        };
+    }
+}
+
+fn main() {
+    let x = foo!(1,2);
+    let y = crate::foo!(1,2);
+}
+"#),
+        @r###"
+    ![0; 17) '{Foo(v...,2,])}': Foo
+    ![1; 4) 'Foo': Foo({unknown}) -> Foo
+    ![1; 16) 'Foo(vec![1,2,])': Foo
+    ![5; 15) 'vec![1,2,]': {unknown}
+    [195; 251) '{     ...,2); }': ()
+    [205; 206) 'x': Foo
+    [228; 229) 'y': {unknown}
+    [232; 248) 'crate:...!(1,2)': {unknown}
+    "###
+    );
+}
+
+#[test]
+fn infer_path_qualified_macros_expanded() {
+    assert_snapshot!(
+        infer(r#"
+#[macro_export]
+macro_rules! foo {
+    () => { 42i32 }
+}
+
+mod m {
+    pub use super::foo as bar;
+}
+
+fn main() {
+    let x = crate::foo!();
+    let y = m::bar!();
+}
+"#),
+        @r###"
+    ![0; 5) '42i32': i32
+    ![0; 5) '42i32': i32
+    [111; 164) '{     ...!(); }': ()
+    [121; 122) 'x': i32
+    [148; 149) 'y': i32
+    "###
+    );
+}
+
+#[test]
+fn infer_type_value_macro_having_same_name() {
+    assert_snapshot!(
+        infer(r#"
+#[macro_export]
+macro_rules! foo {
+    () => {
+        mod foo {
+            pub use super::foo;
+        }
+    };
+    ($x:tt) => {
+        $x
+    };
+}
+
+foo!();
+
+fn foo() {
+    let foo = foo::foo!(42i32);
+}
+"#),
+        @r###"
+    ![0; 5) '42i32': i32
+    [171; 206) '{     ...32); }': ()
+    [181; 184) 'foo': i32
+    "###
+    );
+}
+
+#[test]
+fn processes_impls_generated_by_macros() {
+    let t = type_at(
+        r#"
+//- /main.rs
+macro_rules! m {
+    ($ident:ident) => (impl Trait for $ident {})
+}
+trait Trait { fn foo(self) -> u128 {} }
+struct S;
+m!(S);
+fn test() { S.foo()<|>; }
+"#,
+    );
+    assert_eq!(t, "u128");
+}
+
+#[test]
+fn infer_macro_with_dollar_crate_is_correct_in_expr() {
+    let (db, pos) = TestDB::with_position(
+        r#"
+//- /main.rs crate:main deps:foo
+fn test() {
+    let x = (foo::foo!(1), foo::foo!(2));
+    x<|>;
+}
+
+//- /lib.rs crate:foo
+#[macro_export]
+macro_rules! foo {
+    (1) => { $crate::bar!() };
+    (2) => { 1 + $crate::baz() };
+}
+
+#[macro_export]
+macro_rules! bar {
+    () => { 42 }
+}
+
+pub fn baz() -> usize { 31usize }
+"#,
+    );
+    assert_eq!("(i32, usize)", type_at_pos(&db, pos));
+}
+
+#[ignore]
+#[test]
+fn method_resolution_trait_before_autoref() {
+    let t = type_at(
+        r#"
+//- /main.rs
+trait Trait { fn foo(self) -> u128; }
+struct S;
+impl S { fn foo(&self) -> i8 { 0 } }
+impl Trait for S { fn foo(self) -> u128 { 0 } }
+fn test() { S.foo()<|>; }
+"#,
+    );
+    assert_eq!(t, "u128");
+}
+
+#[ignore]
+#[test]
+fn method_resolution_by_value_before_autoref() {
+    let t = type_at(
+        r#"
+//- /main.rs
+trait Clone { fn clone(&self) -> Self; }
+struct S;
+impl Clone for S {}
+impl Clone for &S {}
+fn test() { (S.clone(), (&S).clone(), (&&S).clone())<|>; }
+"#,
+    );
+    assert_eq!(t, "(S, S, &S)");
+}
+
+#[test]
+fn method_resolution_trait_before_autoderef() {
+    let t = type_at(
+        r#"
+//- /main.rs
+trait Trait { fn foo(self) -> u128; }
+struct S;
+impl S { fn foo(self) -> i8 { 0 } }
+impl Trait for &S { fn foo(self) -> u128 { 0 } }
+fn test() { (&S).foo()<|>; }
+"#,
+    );
+    assert_eq!(t, "u128");
+}
+
+#[test]
+fn method_resolution_impl_before_trait() {
+    let t = type_at(
+        r#"
+//- /main.rs
+trait Trait { fn foo(self) -> u128; }
+struct S;
+impl S { fn foo(self) -> i8 { 0 } }
+impl Trait for S { fn foo(self) -> u128 { 0 } }
+fn test() { S.foo()<|>; }
+"#,
+    );
+    assert_eq!(t, "i8");
+}
+
+#[test]
+fn method_resolution_trait_autoderef() {
+    let t = type_at(
+        r#"
+//- /main.rs
+trait Trait { fn foo(self) -> u128; }
+struct S;
+impl Trait for S { fn foo(self) -> u128 { 0 } }
+fn test() { (&S).foo()<|>; }
+"#,
+    );
+    assert_eq!(t, "u128");
+}
+
+#[test]
+fn method_resolution_trait_from_prelude() {
+    let (db, pos) = TestDB::with_position(
+        r#"
+//- /main.rs crate:main deps:other_crate
+struct S;
+impl Clone for S {}
+
+fn test() {
+    S.clone()<|>;
+}
+
+//- /lib.rs crate:other_crate
+#[prelude_import] use foo::*;
+
+mod foo {
+    trait Clone {
+        fn clone(&self) -> Self;
+    }
+}
+"#,
+    );
+    assert_eq!("S", type_at_pos(&db, pos));
+}
+
+#[test]
+fn method_resolution_where_clause_for_unknown_trait() {
+    // The blanket impl shouldn't apply because we can't even resolve UnknownTrait
+    let t = type_at(
+        r#"
+//- /main.rs
+trait Trait { fn foo(self) -> u128; }
+struct S;
+impl<T> Trait for T where T: UnknownTrait {}
+fn test() { (&S).foo()<|>; }
+"#,
+    );
+    assert_eq!(t, "{unknown}");
+}
+
+#[test]
+fn method_resolution_where_clause_not_met() {
+    // The blanket impl shouldn't apply because we can't prove S: Clone
+    let t = type_at(
+        r#"
+//- /main.rs
+trait Clone {}
+trait Trait { fn foo(self) -> u128; }
+struct S;
+impl<T> Trait for T where T: Clone {}
+fn test() { (&S).foo()<|>; }
+"#,
+    );
+    // This is also to make sure that we don't resolve to the foo method just
+    // because that's the only method named foo we can find, which would make
+    // the below tests not work
+    assert_eq!(t, "{unknown}");
+}
+
+#[test]
+fn method_resolution_where_clause_inline_not_met() {
+    // The blanket impl shouldn't apply because we can't prove S: Clone
+    let t = type_at(
+        r#"
+//- /main.rs
+trait Clone {}
+trait Trait { fn foo(self) -> u128; }
+struct S;
+impl<T: Clone> Trait for T {}
+fn test() { (&S).foo()<|>; }
+"#,
+    );
+    assert_eq!(t, "{unknown}");
+}
+
+#[test]
+fn method_resolution_where_clause_1() {
+    let t = type_at(
+        r#"
+//- /main.rs
+trait Clone {}
+trait Trait { fn foo(self) -> u128; }
+struct S;
+impl Clone for S {}
+impl<T> Trait for T where T: Clone {}
+fn test() { S.foo()<|>; }
+"#,
+    );
+    assert_eq!(t, "u128");
+}
+
+#[test]
+fn method_resolution_where_clause_2() {
+    let t = type_at(
+        r#"
+//- /main.rs
+trait Into<T> { fn into(self) -> T; }
+trait From<T> { fn from(other: T) -> Self; }
+struct S1;
+struct S2;
+impl From<S2> for S1 {}
+impl<T, U> Into<U> for T where U: From<T> {}
+fn test() { S2.into()<|>; }
+"#,
+    );
+    assert_eq!(t, "{unknown}");
+}
+
+#[test]
+fn method_resolution_where_clause_inline() {
+    let t = type_at(
+        r#"
+//- /main.rs
+trait Into<T> { fn into(self) -> T; }
+trait From<T> { fn from(other: T) -> Self; }
+struct S1;
+struct S2;
+impl From<S2> for S1 {}
+impl<T, U: From<T>> Into<U> for T {}
+fn test() { S2.into()<|>; }
+"#,
+    );
+    assert_eq!(t, "{unknown}");
+}
+
+#[test]
+fn method_resolution_encountering_fn_type() {
+    type_at(
+        r#"
+//- /main.rs
+fn foo() {}
+trait FnOnce { fn call(self); }
+fn test() { foo.call()<|>; }
+"#,
+    );
+}
+
+#[test]
+fn method_resolution_slow() {
+    // this can get quite slow if we set the solver size limit too high
+    let t = type_at(
+        r#"
+//- /main.rs
+trait SendX {}
+
+struct S1; impl SendX for S1 {}
+struct S2; impl SendX for S2 {}
+struct U1;
+
+trait Trait { fn method(self); }
+
+struct X1<A, B> {}
+impl<A, B> SendX for X1<A, B> where A: SendX, B: SendX {}
+
+struct S<B, C> {}
+
+trait FnX {}
+
+impl<B, C> Trait for S<B, C> where C: FnX, B: SendX {}
+
+fn test() { (S {}).method()<|>; }
+"#,
+    );
+    assert_eq!(t, "()");
+}
+
+#[test]
+fn shadowing_primitive() {
+    let t = type_at(
+        r#"
+//- /main.rs
+struct i32;
+struct Foo;
+
+impl i32 { fn foo(&self) -> Foo { Foo } }
+
+fn main() {
+    let x: i32 = i32;
+    x.foo()<|>;
+}"#,
+    );
+    assert_eq!(t, "Foo");
+}
+
+#[test]
+fn deref_trait() {
+    let t = type_at(
+        r#"
+//- /main.rs
+#[lang = "deref"]
+trait Deref {
+    type Target;
+    fn deref(&self) -> &Self::Target;
+}
+
+struct Arc<T>;
+impl<T> Deref for Arc<T> {
+    type Target = T;
+}
+
+struct S;
+impl S {
+    fn foo(&self) -> u128 {}
+}
+
+fn test(s: Arc<S>) {
+    (*s, s.foo())<|>;
+}
+"#,
+    );
+    assert_eq!(t, "(S, u128)");
+}
+
+#[test]
+fn deref_trait_with_inference_var() {
+    let t = type_at(
+        r#"
+//- /main.rs
+#[lang = "deref"]
+trait Deref {
+    type Target;
+    fn deref(&self) -> &Self::Target;
+}
+
+struct Arc<T>;
+fn new_arc<T>() -> Arc<T> {}
+impl<T> Deref for Arc<T> {
+    type Target = T;
+}
+
+struct S;
+fn foo(a: Arc<S>) {}
+
+fn test() {
+    let a = new_arc();
+    let b = (*a)<|>;
+    foo(a);
+}
+"#,
+    );
+    assert_eq!(t, "S");
+}
+
+#[test]
+fn deref_trait_infinite_recursion() {
+    let t = type_at(
+        r#"
+//- /main.rs
+#[lang = "deref"]
+trait Deref {
+    type Target;
+    fn deref(&self) -> &Self::Target;
+}
+
+struct S;
+
+impl Deref for S {
+    type Target = S;
+}
+
+fn test(s: S) {
+    s.foo()<|>;
+}
+"#,
+    );
+    assert_eq!(t, "{unknown}");
+}
+
+#[test]
+fn deref_trait_with_question_mark_size() {
+    let t = type_at(
+        r#"
+//- /main.rs
+#[lang = "deref"]
+trait Deref {
+    type Target;
+    fn deref(&self) -> &Self::Target;
+}
+
+struct Arc<T>;
+impl<T> Deref for Arc<T> {
+    type Target = T;
+}
+
+struct S;
+impl S {
+    fn foo(&self) -> u128 {}
+}
+
+fn test(s: Arc<S>) {
+    (*s, s.foo())<|>;
+}
+"#,
+    );
+    assert_eq!(t, "(S, u128)");
+}
+
+#[test]
+fn obligation_from_function_clause() {
+    let t = type_at(
+        r#"
+//- /main.rs
+struct S;
+
+trait Trait<T> {}
+impl Trait<u32> for S {}
+
+fn foo<T: Trait<U>, U>(t: T) -> U {}
+
+fn test(s: S) {
+    foo(s)<|>;
+}
+"#,
+    );
+    assert_eq!(t, "u32");
+}
+
+#[test]
+fn obligation_from_method_clause() {
+    let t = type_at(
+        r#"
+//- /main.rs
+struct S;
+
+trait Trait<T> {}
+impl Trait<isize> for S {}
+
+struct O;
+impl O {
+    fn foo<T: Trait<U>, U>(&self, t: T) -> U {}
+}
+
+fn test() {
+    O.foo(S)<|>;
+}
+"#,
+    );
+    assert_eq!(t, "isize");
+}
+
+#[test]
+fn obligation_from_self_method_clause() {
+    let t = type_at(
+        r#"
+//- /main.rs
+struct S;
+
+trait Trait<T> {}
+impl Trait<i64> for S {}
+
+impl S {
+    fn foo<U>(&self) -> U where Self: Trait<U> {}
+}
+
+fn test() {
+    S.foo()<|>;
+}
+"#,
+    );
+    assert_eq!(t, "i64");
+}
+
+#[test]
+fn obligation_from_impl_clause() {
+    let t = type_at(
+        r#"
+//- /main.rs
+struct S;
+
+trait Trait<T> {}
+impl Trait<&str> for S {}
+
+struct O<T>;
+impl<U, T: Trait<U>> O<T> {
+    fn foo(&self) -> U {}
+}
+
+fn test(o: O<S>) {
+    o.foo()<|>;
+}
+"#,
+    );
+    assert_eq!(t, "&str");
+}
+
+#[test]
+fn generic_param_env_1() {
+    let t = type_at(
+        r#"
+//- /main.rs
+trait Clone {}
+trait Trait { fn foo(self) -> u128; }
+struct S;
+impl Clone for S {}
+impl<T> Trait for T where T: Clone {}
+fn test<T: Clone>(t: T) { t.foo()<|>; }
+"#,
+    );
+    assert_eq!(t, "u128");
+}
+
+#[test]
+fn generic_param_env_1_not_met() {
+    let t = type_at(
+        r#"
+//- /main.rs
+trait Clone {}
+trait Trait { fn foo(self) -> u128; }
+struct S;
+impl Clone for S {}
+impl<T> Trait for T where T: Clone {}
+fn test<T>(t: T) { t.foo()<|>; }
+"#,
+    );
+    assert_eq!(t, "{unknown}");
+}
+
+#[test]
+fn generic_param_env_2() {
+    let t = type_at(
+        r#"
+//- /main.rs
+trait Trait { fn foo(self) -> u128; }
+struct S;
+impl Trait for S {}
+fn test<T: Trait>(t: T) { t.foo()<|>; }
+"#,
+    );
+    assert_eq!(t, "u128");
+}
+
+#[test]
+fn generic_param_env_2_not_met() {
+    let t = type_at(
+        r#"
+//- /main.rs
+trait Trait { fn foo(self) -> u128; }
+struct S;
+impl Trait for S {}
+fn test<T>(t: T) { t.foo()<|>; }
+"#,
+    );
+    assert_eq!(t, "{unknown}");
+}
+
+#[test]
+fn generic_param_env_deref() {
+    let t = type_at(
+        r#"
+//- /main.rs
+#[lang = "deref"]
+trait Deref {
+    type Target;
+}
+trait Trait {}
+impl<T> Deref for T where T: Trait {
+    type Target = i128;
+}
+fn test<T: Trait>(t: T) { (*t)<|>; }
+"#,
+    );
+    assert_eq!(t, "i128");
+}
+
+#[test]
+fn associated_type_placeholder() {
+    let t = type_at(
+        r#"
+//- /main.rs
+pub trait ApplyL {
+    type Out;
+}
+
+pub struct RefMutL<T>;
+
+impl<T> ApplyL for RefMutL<T> {
+    type Out = <T as ApplyL>::Out;
+}
+
+fn test<T: ApplyL>() {
+    let y: <RefMutL<T> as ApplyL>::Out = no_matter;
+    y<|>;
+}
+"#,
+    );
+    // inside the generic function, the associated type gets normalized to a placeholder `ApplL::Out<T>` [https://rust-lang.github.io/rustc-guide/traits/associated-types.html#placeholder-associated-types].
+    // FIXME: fix type parameter names going missing when going through Chalk
+    assert_eq!(t, "ApplyL::Out<[missing name]>");
+}
+
+#[test]
+fn associated_type_placeholder_2() {
+    let t = type_at(
+        r#"
+//- /main.rs
+pub trait ApplyL {
+    type Out;
+}
+fn foo<T: ApplyL>(t: T) -> <T as ApplyL>::Out;
+
+fn test<T: ApplyL>(t: T) {
+    let y = foo(t);
+    y<|>;
+}
+"#,
+    );
+    // FIXME here Chalk doesn't normalize the type to a placeholder. I think we
+    // need to add a rule like Normalize(<T as ApplyL>::Out -> ApplyL::Out<T>)
+    // to the trait env ourselves here; probably Chalk can't do this by itself.
+    // assert_eq!(t, "ApplyL::Out<[missing name]>");
+    assert_eq!(t, "{unknown}");
+}
+
+#[test]
+fn impl_trait() {
+    assert_snapshot!(
+        infer(r#"
+trait Trait<T> {
+    fn foo(&self) -> T;
+    fn foo2(&self) -> i64;
+}
+fn bar() -> impl Trait<u64> {}
+
+fn test(x: impl Trait<u64>, y: &impl Trait<u64>) {
+    x;
+    y;
+    let z = bar();
+    x.foo();
+    y.foo();
+    z.foo();
+    x.foo2();
+    y.foo2();
+    z.foo2();
+}
+"#),
+        @r###"
+    [30; 34) 'self': &Self
+    [55; 59) 'self': &Self
+    [99; 101) '{}': ()
+    [111; 112) 'x': impl Trait<u64>
+    [131; 132) 'y': &impl Trait<u64>
+    [152; 269) '{     ...2(); }': ()
+    [158; 159) 'x': impl Trait<u64>
+    [165; 166) 'y': &impl Trait<u64>
+    [176; 177) 'z': impl Trait<u64>
+    [180; 183) 'bar': fn bar() -> impl Trait<u64>
+    [180; 185) 'bar()': impl Trait<u64>
+    [191; 192) 'x': impl Trait<u64>
+    [191; 198) 'x.foo()': u64
+    [204; 205) 'y': &impl Trait<u64>
+    [204; 211) 'y.foo()': u64
+    [217; 218) 'z': impl Trait<u64>
+    [217; 224) 'z.foo()': u64
+    [230; 231) 'x': impl Trait<u64>
+    [230; 238) 'x.foo2()': i64
+    [244; 245) 'y': &impl Trait<u64>
+    [244; 252) 'y.foo2()': i64
+    [258; 259) 'z': impl Trait<u64>
+    [258; 266) 'z.foo2()': i64
+    "###
+    );
+}
+
+#[test]
+fn dyn_trait() {
+    assert_snapshot!(
+        infer(r#"
+trait Trait<T> {
+    fn foo(&self) -> T;
+    fn foo2(&self) -> i64;
+}
+fn bar() -> dyn Trait<u64> {}
+
+fn test(x: dyn Trait<u64>, y: &dyn Trait<u64>) {
+    x;
+    y;
+    let z = bar();
+    x.foo();
+    y.foo();
+    z.foo();
+    x.foo2();
+    y.foo2();
+    z.foo2();
+}
+"#),
+        @r###"
+    [30; 34) 'self': &Self
+    [55; 59) 'self': &Self
+    [98; 100) '{}': ()
+    [110; 111) 'x': dyn Trait<u64>
+    [129; 130) 'y': &dyn Trait<u64>
+    [149; 266) '{     ...2(); }': ()
+    [155; 156) 'x': dyn Trait<u64>
+    [162; 163) 'y': &dyn Trait<u64>
+    [173; 174) 'z': dyn Trait<u64>
+    [177; 180) 'bar': fn bar() -> dyn Trait<u64>
+    [177; 182) 'bar()': dyn Trait<u64>
+    [188; 189) 'x': dyn Trait<u64>
+    [188; 195) 'x.foo()': u64
+    [201; 202) 'y': &dyn Trait<u64>
+    [201; 208) 'y.foo()': u64
+    [214; 215) 'z': dyn Trait<u64>
+    [214; 221) 'z.foo()': u64
+    [227; 228) 'x': dyn Trait<u64>
+    [227; 235) 'x.foo2()': i64
+    [241; 242) 'y': &dyn Trait<u64>
+    [241; 249) 'y.foo2()': i64
+    [255; 256) 'z': dyn Trait<u64>
+    [255; 263) 'z.foo2()': i64
+    "###
+    );
+}
+
+#[test]
+fn dyn_trait_bare() {
+    assert_snapshot!(
+        infer(r#"
+trait Trait {
+    fn foo(&self) -> u64;
+}
+fn bar() -> Trait {}
+
+fn test(x: Trait, y: &Trait) -> u64 {
+    x;
+    y;
+    let z = bar();
+    x.foo();
+    y.foo();
+    z.foo();
+}
+"#),
+        @r###"
+    [27; 31) 'self': &Self
+    [61; 63) '{}': ()
+    [73; 74) 'x': dyn Trait
+    [83; 84) 'y': &dyn Trait
+    [101; 176) '{     ...o(); }': ()
+    [107; 108) 'x': dyn Trait
+    [114; 115) 'y': &dyn Trait
+    [125; 126) 'z': dyn Trait
+    [129; 132) 'bar': fn bar() -> dyn Trait
+    [129; 134) 'bar()': dyn Trait
+    [140; 141) 'x': dyn Trait
+    [140; 147) 'x.foo()': u64
+    [153; 154) 'y': &dyn Trait
+    [153; 160) 'y.foo()': u64
+    [166; 167) 'z': dyn Trait
+    [166; 173) 'z.foo()': u64
+    "###
+    );
+}
+
+#[test]
+fn weird_bounds() {
+    assert_snapshot!(
+        infer(r#"
+trait Trait {}
+fn test() {
+    let a: impl Trait + 'lifetime = foo;
+    let b: impl 'lifetime = foo;
+    let b: impl (Trait) = foo;
+    let b: impl ('lifetime) = foo;
+    let d: impl ?Sized = foo;
+    let e: impl Trait + ?Sized = foo;
+}
+"#),
+        @r###"
+    [26; 237) '{     ...foo; }': ()
+    [36; 37) 'a': impl Trait + {error}
+    [64; 67) 'foo': impl Trait + {error}
+    [77; 78) 'b': impl {error}
+    [97; 100) 'foo': impl {error}
+    [110; 111) 'b': impl Trait
+    [128; 131) 'foo': impl Trait
+    [141; 142) 'b': impl {error}
+    [163; 166) 'foo': impl {error}
+    [176; 177) 'd': impl {error}
+    [193; 196) 'foo': impl {error}
+    [206; 207) 'e': impl Trait + {error}
+    [231; 234) 'foo': impl Trait + {error}
+    "###
+    );
+}
+
+#[test]
+fn assoc_type_bindings() {
+    assert_snapshot!(
+        infer(r#"
+trait Trait {
+    type Type;
+}
+
+fn get<T: Trait>(t: T) -> <T as Trait>::Type {}
+fn get2<U, T: Trait<Type = U>>(t: T) -> U {}
+fn set<T: Trait<Type = u64>>(t: T) -> T {t}
+
+struct S<T>;
+impl<T> Trait for S<T> { type Type = T; }
+
+fn test<T: Trait<Type = u32>>(x: T, y: impl Trait<Type = i64>) {
+    get(x);
+    get2(x);
+    get(y);
+    get2(y);
+    get(set(S));
+    get2(set(S));
+    get2(S::<str>);
+}
+"#),
+        @r###"
+    [50; 51) 't': T
+    [78; 80) '{}': ()
+    [112; 113) 't': T
+    [123; 125) '{}': ()
+    [155; 156) 't': T
+    [166; 169) '{t}': T
+    [167; 168) 't': T
+    [257; 258) 'x': T
+    [263; 264) 'y': impl Trait<Type = i64>
+    [290; 398) '{     ...r>); }': ()
+    [296; 299) 'get': fn get<T>(T) -> <T as Trait>::Type
+    [296; 302) 'get(x)': {unknown}
+    [300; 301) 'x': T
+    [308; 312) 'get2': fn get2<{unknown}, T>(T) -> U
+    [308; 315) 'get2(x)': {unknown}
+    [313; 314) 'x': T
+    [321; 324) 'get': fn get<impl Trait<Type = i64>>(T) -> <T as Trait>::Type
+    [321; 327) 'get(y)': {unknown}
+    [325; 326) 'y': impl Trait<Type = i64>
+    [333; 337) 'get2': fn get2<{unknown}, impl Trait<Type = i64>>(T) -> U
+    [333; 340) 'get2(y)': {unknown}
+    [338; 339) 'y': impl Trait<Type = i64>
+    [346; 349) 'get': fn get<S<u64>>(T) -> <T as Trait>::Type
+    [346; 357) 'get(set(S))': u64
+    [350; 353) 'set': fn set<S<u64>>(T) -> T
+    [350; 356) 'set(S)': S<u64>
+    [354; 355) 'S': S<u64>
+    [363; 367) 'get2': fn get2<u64, S<u64>>(T) -> U
+    [363; 375) 'get2(set(S))': u64
+    [368; 371) 'set': fn set<S<u64>>(T) -> T
+    [368; 374) 'set(S)': S<u64>
+    [372; 373) 'S': S<u64>
+    [381; 385) 'get2': fn get2<str, S<str>>(T) -> U
+    [381; 395) 'get2(S::<str>)': str
+    [386; 394) 'S::<str>': S<str>
+    "###
+    );
+}
+
+#[test]
+fn impl_trait_assoc_binding_projection_bug() {
+    let (db, pos) = TestDB::with_position(
+        r#"
+//- /main.rs crate:main deps:std
+pub trait Language {
+    type Kind;
+}
+pub enum RustLanguage {}
+impl Language for RustLanguage {
+    type Kind = SyntaxKind;
+}
+struct SyntaxNode<L> {}
+fn foo() -> impl Iterator<Item = SyntaxNode<RustLanguage>> {}
+
+trait Clone {
+    fn clone(&self) -> Self;
+}
+
+fn api_walkthrough() {
+    for node in foo() {
+        node.clone()<|>;
+    }
+}
+
+//- /std.rs crate:std
+#[prelude_import] use iter::*;
+mod iter {
+    trait IntoIterator {
+        type Item;
+    }
+    trait Iterator {
+        type Item;
+    }
+    impl<T: Iterator> IntoIterator for T {
+        type Item = <T as Iterator>::Item;
+    }
+}
+"#,
+    );
+    assert_eq!("{unknown}", type_at_pos(&db, pos));
+}
+
+#[test]
+fn projection_eq_within_chalk() {
+    // std::env::set_var("CHALK_DEBUG", "1");
+    assert_snapshot!(
+        infer(r#"
+trait Trait1 {
+    type Type;
+}
+trait Trait2<T> {
+    fn foo(self) -> T;
+}
+impl<T, U> Trait2<T> for U where U: Trait1<Type = T> {}
+
+fn test<T: Trait1<Type = u32>>(x: T) {
+    x.foo();
+}
+"#),
+        @r###"
+    [62; 66) 'self': Self
+    [164; 165) 'x': T
+    [170; 186) '{     ...o(); }': ()
+    [176; 177) 'x': T
+    [176; 183) 'x.foo()': {unknown}
+    "###
+    );
+}
+
+#[test]
+fn where_clause_trait_in_scope_for_method_resolution() {
+    let t = type_at(
+        r#"
+//- /main.rs
+mod foo {
+    trait Trait {
+        fn foo(&self) -> u32 {}
+    }
+}
+
+fn test<T: foo::Trait>(x: T) {
+    x.foo()<|>;
+}
+"#,
+    );
+    assert_eq!(t, "u32");
+}
+
+#[test]
+fn super_trait_method_resolution() {
+    assert_snapshot!(
+        infer(r#"
+mod foo {
+    trait SuperTrait {
+        fn foo(&self) -> u32 {}
+    }
+}
+trait Trait1: foo::SuperTrait {}
+trait Trait2 where Self: foo::SuperTrait {}
+
+fn test<T: Trait1, U: Trait2>(x: T, y: U) {
+    x.foo();
+    y.foo();
+}
+"#),
+        @r###"
+    [50; 54) 'self': &Self
+    [63; 65) '{}': ()
+    [182; 183) 'x': T
+    [188; 189) 'y': U
+    [194; 223) '{     ...o(); }': ()
+    [200; 201) 'x': T
+    [200; 207) 'x.foo()': u32
+    [213; 214) 'y': U
+    [213; 220) 'y.foo()': u32
+    "###
+    );
+}
+
+#[test]
+fn super_trait_cycle() {
+    // This just needs to not crash
+    assert_snapshot!(
+        infer(r#"
+trait A: B {}
+trait B: A {}
+
+fn test<T: A>(x: T) {
+    x.foo();
+}
+"#),
+        @r###"
+    [44; 45) 'x': T
+    [50; 66) '{     ...o(); }': ()
+    [56; 57) 'x': T
+    [56; 63) 'x.foo()': {unknown}
+    "###
+    );
+}
+
+#[test]
+fn super_trait_assoc_type_bounds() {
+    assert_snapshot!(
+        infer(r#"
+trait SuperTrait { type Type; }
+trait Trait where Self: SuperTrait {}
+
+fn get2<U, T: Trait<Type = U>>(t: T) -> U {}
+fn set<T: Trait<Type = u64>>(t: T) -> T {t}
+
+struct S<T>;
+impl<T> SuperTrait for S<T> { type Type = T; }
+impl<T> Trait for S<T> {}
+
+fn test() {
+    get2(set(S));
+}
+"#),
+        @r###"
+    [103; 104) 't': T
+    [114; 116) '{}': ()
+    [146; 147) 't': T
+    [157; 160) '{t}': T
+    [158; 159) 't': T
+    [259; 280) '{     ...S)); }': ()
+    [265; 269) 'get2': fn get2<u64, S<u64>>(T) -> U
+    [265; 277) 'get2(set(S))': u64
+    [270; 273) 'set': fn set<S<u64>>(T) -> T
+    [270; 276) 'set(S)': S<u64>
+    [274; 275) 'S': S<u64>
+    "###
+    );
+}
+
+#[test]
+fn fn_trait() {
+    assert_snapshot!(
+        infer(r#"
+trait FnOnce<Args> {
+    type Output;
+
+    fn call_once(self, args: Args) -> <Self as FnOnce<Args>>::Output;
+}
+
+fn test<F: FnOnce(u32, u64) -> u128>(f: F) {
+    f.call_once((1, 2));
+}
+"#),
+        @r###"
+    [57; 61) 'self': Self
+    [63; 67) 'args': Args
+    [150; 151) 'f': F
+    [156; 184) '{     ...2)); }': ()
+    [162; 163) 'f': F
+    [162; 181) 'f.call...1, 2))': {unknown}
+    [174; 180) '(1, 2)': (u32, u64)
+    [175; 176) '1': u32
+    [178; 179) '2': u64
+    "###
+    );
+}
+
+#[test]
+fn closure_1() {
+    assert_snapshot!(
+        infer(r#"
+#[lang = "fn_once"]
+trait FnOnce<Args> {
+    type Output;
+}
+
+enum Option<T> { Some(T), None }
+impl<T> Option<T> {
+    fn map<U, F: FnOnce(T) -> U>(self, f: F) -> Option<U> {}
+}
+
+fn test() {
+    let x = Option::Some(1u32);
+    x.map(|v| v + 1);
+    x.map(|_v| 1u64);
+    let y: Option<i64> = x.map(|_v| 1);
+}
+"#),
+        @r###"
+    [148; 152) 'self': Option<T>
+    [154; 155) 'f': F
+    [173; 175) '{}': ()
+    [189; 308) '{     ... 1); }': ()
+    [199; 200) 'x': Option<u32>
+    [203; 215) 'Option::Some': Some<u32>(T) -> Option<T>
+    [203; 221) 'Option...(1u32)': Option<u32>
+    [216; 220) '1u32': u32
+    [227; 228) 'x': Option<u32>
+    [227; 243) 'x.map(...v + 1)': Option<u32>
+    [233; 242) '|v| v + 1': |u32| -> u32
+    [234; 235) 'v': u32
+    [237; 238) 'v': u32
+    [237; 242) 'v + 1': u32
+    [241; 242) '1': u32
+    [249; 250) 'x': Option<u32>
+    [249; 265) 'x.map(... 1u64)': Option<u64>
+    [255; 264) '|_v| 1u64': |u32| -> u64
+    [256; 258) '_v': u32
+    [260; 264) '1u64': u64
+    [275; 276) 'y': Option<i64>
+    [292; 293) 'x': Option<u32>
+    [292; 305) 'x.map(|_v| 1)': Option<i64>
+    [298; 304) '|_v| 1': |u32| -> i64
+    [299; 301) '_v': u32
+    [303; 304) '1': i64
+    "###
+    );
+}
+
+#[test]
+fn closure_2() {
+    assert_snapshot!(
+        infer(r#"
+trait FnOnce<Args> {
+    type Output;
+}
+
+fn test<F: FnOnce(u32) -> u64>(f: F) {
+    f(1);
+    let g = |v| v + 1;
+    g(1u64);
+    let h = |v| 1u128 + v;
+}
+"#),
+        @r###"
+    [73; 74) 'f': F
+    [79; 155) '{     ...+ v; }': ()
+    [85; 86) 'f': F
+    [85; 89) 'f(1)': {unknown}
+    [87; 88) '1': i32
+    [99; 100) 'g': |u64| -> i32
+    [103; 112) '|v| v + 1': |u64| -> i32
+    [104; 105) 'v': u64
+    [107; 108) 'v': u64
+    [107; 112) 'v + 1': i32
+    [111; 112) '1': i32
+    [118; 119) 'g': |u64| -> i32
+    [118; 125) 'g(1u64)': i32
+    [120; 124) '1u64': u64
+    [135; 136) 'h': |u128| -> u128
+    [139; 152) '|v| 1u128 + v': |u128| -> u128
+    [140; 141) 'v': u128
+    [143; 148) '1u128': u128
+    [143; 152) '1u128 + v': u128
+    [151; 152) 'v': u128
+    "###
+    );
+}
+
+#[test]
+fn closure_as_argument_inference_order() {
+    assert_snapshot!(
+        infer(r#"
+#[lang = "fn_once"]
+trait FnOnce<Args> {
+    type Output;
+}
+
+fn foo1<T, U, F: FnOnce(T) -> U>(x: T, f: F) -> U {}
+fn foo2<T, U, F: FnOnce(T) -> U>(f: F, x: T) -> U {}
+
+struct S;
+impl S {
+    fn method(self) -> u64;
+
+    fn foo1<T, U, F: FnOnce(T) -> U>(self, x: T, f: F) -> U {}
+    fn foo2<T, U, F: FnOnce(T) -> U>(self, f: F, x: T) -> U {}
+}
+
+fn test() {
+    let x1 = foo1(S, |s| s.method());
+    let x2 = foo2(|s| s.method(), S);
+    let x3 = S.foo1(S, |s| s.method());
+    let x4 = S.foo2(|s| s.method(), S);
+}
+"#),
+        @r###"
+    [95; 96) 'x': T
+    [101; 102) 'f': F
+    [112; 114) '{}': ()
+    [148; 149) 'f': F
+    [154; 155) 'x': T
+    [165; 167) '{}': ()
+    [202; 206) 'self': S
+    [254; 258) 'self': S
+    [260; 261) 'x': T
+    [266; 267) 'f': F
+    [277; 279) '{}': ()
+    [317; 321) 'self': S
+    [323; 324) 'f': F
+    [329; 330) 'x': T
+    [340; 342) '{}': ()
+    [356; 515) '{     ... S); }': ()
+    [366; 368) 'x1': u64
+    [371; 375) 'foo1': fn foo1<S, u64, |S| -> u64>(T, F) -> U
+    [371; 394) 'foo1(S...hod())': u64
+    [376; 377) 'S': S
+    [379; 393) '|s| s.method()': |S| -> u64
+    [380; 381) 's': S
+    [383; 384) 's': S
+    [383; 393) 's.method()': u64
+    [404; 406) 'x2': u64
+    [409; 413) 'foo2': fn foo2<S, u64, |S| -> u64>(F, T) -> U
+    [409; 432) 'foo2(|...(), S)': u64
+    [414; 428) '|s| s.method()': |S| -> u64
+    [415; 416) 's': S
+    [418; 419) 's': S
+    [418; 428) 's.method()': u64
+    [430; 431) 'S': S
+    [442; 444) 'x3': u64
+    [447; 448) 'S': S
+    [447; 472) 'S.foo1...hod())': u64
+    [454; 455) 'S': S
+    [457; 471) '|s| s.method()': |S| -> u64
+    [458; 459) 's': S
+    [461; 462) 's': S
+    [461; 471) 's.method()': u64
+    [482; 484) 'x4': u64
+    [487; 488) 'S': S
+    [487; 512) 'S.foo2...(), S)': u64
+    [494; 508) '|s| s.method()': |S| -> u64
+    [495; 496) 's': S
+    [498; 499) 's': S
+    [498; 508) 's.method()': u64
+    [510; 511) 'S': S
+    "###
+    );
+}
+
+#[test]
+fn unselected_projection_in_trait_env_1() {
+    let t = type_at(
+        r#"
+//- /main.rs
+trait Trait {
+    type Item;
+}
+
+trait Trait2 {
+    fn foo(&self) -> u32;
+}
+
+fn test<T: Trait>() where T::Item: Trait2 {
+    let x: T::Item = no_matter;
+    x.foo()<|>;
+}
+"#,
+    );
+    assert_eq!(t, "u32");
+}
+
+#[test]
+fn unselected_projection_in_trait_env_2() {
+    let t = type_at(
+        r#"
+//- /main.rs
+trait Trait<T> {
+    type Item;
+}
+
+trait Trait2 {
+    fn foo(&self) -> u32;
+}
+
+fn test<T, U>() where T::Item: Trait2, T: Trait<U::Item>, U: Trait<()> {
+    let x: T::Item = no_matter;
+    x.foo()<|>;
+}
+"#,
+    );
+    assert_eq!(t, "u32");
+}
+
+#[test]
+// FIXME this is currently a Salsa panic; it would be nicer if it just returned
+// in Unknown, and we should be able to do that once Salsa allows us to handle
+// the cycle. But at least it doesn't overflow for now.
+#[should_panic]
+fn unselected_projection_in_trait_env_cycle_1() {
+    let t = type_at(
+        r#"
+//- /main.rs
+trait Trait {
+    type Item;
+}
+
+trait Trait2<T> {}
+
+fn test<T: Trait>() where T: Trait2<T::Item> {
+    let x: T::Item = no_matter<|>;
+}
+"#,
+    );
+    // this is a legitimate cycle
+    assert_eq!(t, "{unknown}");
+}
+
+#[test]
+// FIXME this is currently a Salsa panic; it would be nicer if it just returned
+// in Unknown, and we should be able to do that once Salsa allows us to handle
+// the cycle. But at least it doesn't overflow for now.
+#[should_panic]
+fn unselected_projection_in_trait_env_cycle_2() {
+    let t = type_at(
+        r#"
+//- /main.rs
+trait Trait<T> {
+    type Item;
+}
+
+fn test<T, U>() where T: Trait<U::Item>, U: Trait<T::Item> {
+    let x: T::Item = no_matter<|>;
+}
+"#,
+    );
+    // this is a legitimate cycle
+    assert_eq!(t, "{unknown}");
+}
+
+fn type_at_pos(db: &TestDB, pos: FilePosition) -> String {
+    let file = db.parse(pos.file_id).ok().unwrap();
+    let expr = algo::find_node_at_offset::<ast::Expr>(file.syntax(), pos.offset).unwrap();
+
+    let module = db.module_for_file(pos.file_id);
+    let crate_def_map = db.crate_def_map(module.krate);
+    for decl in crate_def_map[module.local_id].scope.declarations() {
+        if let ModuleDefId::FunctionId(func) = decl {
+            let (_body, source_map) = db.body_with_source_map(func.into());
+            if let Some(expr_id) = source_map.node_expr(Source::new(pos.file_id.into(), &expr)) {
+                let infer = db.infer(func.into());
+                let ty = &infer[expr_id];
+                return ty.display(db).to_string();
+            }
+        }
+    }
+    panic!("Can't find expression")
+}
+
+fn type_at(content: &str) -> String {
+    let (db, file_pos) = TestDB::with_position(content);
+    type_at_pos(&db, file_pos)
+}
+
+fn infer(content: &str) -> String {
+    let (db, file_id) = TestDB::with_single_file(content);
+
+    let mut acc = String::new();
+
+    let mut infer_def = |inference_result: Arc<InferenceResult>,
+                         body_source_map: Arc<BodySourceMap>| {
+        let mut types = Vec::new();
+
+        for (pat, ty) in inference_result.type_of_pat.iter() {
+            let syntax_ptr = match body_source_map.pat_syntax(pat) {
+                Some(sp) => {
+                    sp.map(|ast| ast.either(|it| it.syntax_node_ptr(), |it| it.syntax_node_ptr()))
+                }
+                None => continue,
+            };
+            types.push((syntax_ptr, ty));
+        }
+
+        for (expr, ty) in inference_result.type_of_expr.iter() {
+            let syntax_ptr = match body_source_map.expr_syntax(expr) {
+                Some(sp) => {
+                    sp.map(|ast| ast.either(|it| it.syntax_node_ptr(), |it| it.syntax_node_ptr()))
+                }
+                None => continue,
+            };
+            types.push((syntax_ptr, ty));
+        }
+
+        // sort ranges for consistency
+        types.sort_by_key(|(src_ptr, _)| {
+            (src_ptr.value.range().start(), src_ptr.value.range().end())
+        });
+        for (src_ptr, ty) in &types {
+            let node = src_ptr.value.to_node(&src_ptr.file_syntax(&db));
+
+            let (range, text) = if let Some(self_param) = ast::SelfParam::cast(node.clone()) {
+                (self_param.self_kw_token().text_range(), "self".to_string())
+            } else {
+                (src_ptr.value.range(), node.text().to_string().replace("\n", " "))
+            };
+            let macro_prefix = if src_ptr.file_id != file_id.into() { "!" } else { "" };
+            write!(
+                acc,
+                "{}{} '{}': {}\n",
+                macro_prefix,
+                range,
+                ellipsize(text, 15),
+                ty.display(&db)
+            )
+            .unwrap();
+        }
+    };
+
+    let module = db.module_for_file(file_id);
+    let crate_def_map = db.crate_def_map(module.krate);
+
+    let mut defs: Vec<DefWithBodyId> = Vec::new();
+    visit_module(&db, &crate_def_map, module.local_id, &mut |it| defs.push(it));
+    defs.sort_by_key(|def| match def {
+        DefWithBodyId::FunctionId(it) => {
+            it.lookup(&db).ast_id.to_node(&db).syntax().text_range().start()
+        }
+        DefWithBodyId::ConstId(it) => {
+            it.lookup(&db).ast_id.to_node(&db).syntax().text_range().start()
+        }
+        DefWithBodyId::StaticId(it) => {
+            it.lookup(&db).ast_id.to_node(&db).syntax().text_range().start()
+        }
+    });
+    for def in defs {
+        let (_body, source_map) = db.body_with_source_map(def);
+        let infer = db.infer(def);
+        infer_def(infer, source_map);
+    }
+
+    acc.truncate(acc.trim_end().len());
+    acc
+}
+
+fn visit_module(
+    db: &TestDB,
+    crate_def_map: &CrateDefMap,
+    module_id: LocalModuleId,
+    cb: &mut dyn FnMut(DefWithBodyId),
+) {
+    for decl in crate_def_map[module_id].scope.declarations() {
+        match decl {
+            ModuleDefId::FunctionId(it) => cb(it.into()),
+            ModuleDefId::ConstId(it) => cb(it.into()),
+            ModuleDefId::StaticId(it) => cb(it.into()),
+            ModuleDefId::TraitId(it) => {
+                let trait_data = db.trait_data(it);
+                for &(_, item) in trait_data.items.iter() {
+                    match item {
+                        AssocItemId::FunctionId(it) => cb(it.into()),
+                        AssocItemId::ConstId(it) => cb(it.into()),
+                        AssocItemId::TypeAliasId(_) => (),
+                    }
+                }
+            }
+            ModuleDefId::ModuleId(it) => visit_module(db, crate_def_map, it.local_id, cb),
+            _ => (),
+        }
+    }
+    for &impl_id in crate_def_map[module_id].impls.iter() {
+        let impl_data = db.impl_data(impl_id);
+        for &item in impl_data.items.iter() {
+            match item {
+                AssocItemId::FunctionId(it) => cb(it.into()),
+                AssocItemId::ConstId(it) => cb(it.into()),
+                AssocItemId::TypeAliasId(_) => (),
+            }
+        }
+    }
+}
+
+fn ellipsize(mut text: String, max_len: usize) -> String {
+    if text.len() <= max_len {
+        return text;
+    }
+    let ellipsis = "...";
+    let e_len = ellipsis.len();
+    let mut prefix_len = (max_len - e_len) / 2;
+    while !text.is_char_boundary(prefix_len) {
+        prefix_len += 1;
+    }
+    let mut suffix_len = max_len - e_len - prefix_len;
+    while !text.is_char_boundary(text.len() - suffix_len) {
+        suffix_len += 1;
+    }
+    text.replace_range(prefix_len..text.len() - suffix_len, ellipsis);
+    text
+}
+
+#[test]
+fn typing_whitespace_inside_a_function_should_not_invalidate_types() {
+    let (mut db, pos) = TestDB::with_position(
+        "
+        //- /lib.rs
+        fn foo() -> i32 {
+            <|>1 + 1
+        }
+    ",
+    );
+    {
+        let events = db.log_executed(|| {
+            let module = db.module_for_file(pos.file_id);
+            let crate_def_map = db.crate_def_map(module.krate);
+            visit_module(&db, &crate_def_map, module.local_id, &mut |def| {
+                db.infer(def);
+            });
+        });
+        assert!(format!("{:?}", events).contains("infer"))
+    }
+
+    let new_text = "
+        fn foo() -> i32 {
+            1
+            +
+            1
+        }
+    "
+    .to_string();
+
+    db.query_mut(ra_db::FileTextQuery).set(pos.file_id, Arc::new(new_text));
+
+    {
+        let events = db.log_executed(|| {
+            let module = db.module_for_file(pos.file_id);
+            let crate_def_map = db.crate_def_map(module.krate);
+            visit_module(&db, &crate_def_map, module.local_id, &mut |def| {
+                db.infer(def);
+            });
+        });
+        assert!(!format!("{:?}", events).contains("infer"), "{:#?}", events)
+    }
+}
+
+#[test]
+fn no_such_field_diagnostics() {
+    let diagnostics = TestDB::with_files(
+        r"
+        //- /lib.rs
+        struct S { foo: i32, bar: () }
+        impl S {
+            fn new() -> S {
+                S {
+                    foo: 92,
+                    baz: 62,
+                }
+            }
+        }
+        ",
+    )
+    .diagnostics();
+
+    assert_snapshot!(diagnostics, @r###"
+    "baz: 62": no such field
+    "{\n            foo: 92,\n            baz: 62,\n        }": Missing structure fields:
+    - bar
+    "###
+    );
+}
+
+#[test]
+fn infer_builtin_macros_line() {
+    assert_snapshot!(
+        infer(r#"
+#[rustc_builtin_macro]
+macro_rules! line {() => {}}
+
+fn main() {
+    let x = line!();
+}
+"#),
+        @r###"
+    ![0; 1) '6': i32
+    [64; 88) '{     ...!(); }': ()
+    [74; 75) 'x': i32
+    "###
+    );
+}
+
+#[test]
+fn infer_builtin_macros_file() {
+    assert_snapshot!(
+        infer(r#"
+#[rustc_builtin_macro]
+macro_rules! file {() => {}}
+
+fn main() {
+    let x = file!();
+}
+"#),
+        @r###"
+    ![0; 2) '""': &str
+    [64; 88) '{     ...!(); }': ()
+    [74; 75) 'x': &str
+    "###
+    );
+}
+
+#[test]
+fn infer_builtin_macros_column() {
+    assert_snapshot!(
+        infer(r#"
+#[rustc_builtin_macro]
+macro_rules! column {() => {}}
+
+fn main() {
+    let x = column!();
+}
+"#),
+        @r###"
+    ![0; 2) '13': i32
+    [66; 92) '{     ...!(); }': ()
+    [76; 77) 'x': i32
+    "###
+    );
+}
diff --git a/crates/ra_hir_ty/src/tests/coercion.rs b/crates/ra_hir_ty/src/tests/coercion.rs
new file mode 100644
index 000000000..1530fcc63
--- /dev/null
+++ b/crates/ra_hir_ty/src/tests/coercion.rs
@@ -0,0 +1,369 @@
+use insta::assert_snapshot;
+use test_utils::covers;
+
+// Infer with some common definitions and impls.
+fn infer(source: &str) -> String {
+    let defs = r#"
+        #[lang = "sized"]
+        pub trait Sized {}
+        #[lang = "unsize"]
+        pub trait Unsize<T: ?Sized> {}
+        #[lang = "coerce_unsized"]
+        pub trait CoerceUnsized<T> {}
+
+        impl<'a, 'b: 'a, T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<&'a U> for &'b T {}
+        impl<T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<*mut U> for *mut T {}
+    "#;
+
+    // Append to the end to keep positions unchanged.
+    super::infer(&format!("{}{}", source, defs))
+}
+
+#[test]
+fn infer_block_expr_type_mismatch() {
+    assert_snapshot!(
+        infer(r#"
+fn test() {
+    let a: i32 = { 1i64 };
+}
+"#),
+        @r###"
+    [11; 41) '{     ...4 }; }': ()
+    [21; 22) 'a': i32
+    [30; 38) '{ 1i64 }': i64
+    [32; 36) '1i64': i64
+    "###);
+}
+
+#[test]
+fn coerce_places() {
+    assert_snapshot!(
+        infer(r#"
+struct S<T> { a: T }
+
+fn f<T>(_: &[T]) -> T { loop {} }
+fn g<T>(_: S<&[T]>) -> T { loop {} }
+
+fn gen<T>() -> *mut [T; 2] { loop {} }
+fn test1<U>() -> *mut [U] {
+    gen()
+}
+
+fn test2() {
+    let arr: &[u8; 1] = &[1];
+
+    let a: &[_] = arr;
+    let b = f(arr);
+    let c: &[_] = { arr };
+    let d = g(S { a: arr });
+    let e: [&[_]; 1] = [arr];
+    let f: [&[_]; 2] = [arr; 2];
+    let g: (&[_], &[_]) = (arr, arr);
+}
+"#),
+        @r###"
+    [31; 32) '_': &[T]
+    [45; 56) '{ loop {} }': T
+    [47; 54) 'loop {}': !
+    [52; 54) '{}': ()
+    [65; 66) '_': S<&[T]>
+    [82; 93) '{ loop {} }': T
+    [84; 91) 'loop {}': !
+    [89; 91) '{}': ()
+    [122; 133) '{ loop {} }': *mut [T;_]
+    [124; 131) 'loop {}': !
+    [129; 131) '{}': ()
+    [160; 173) '{     gen() }': *mut [U]
+    [166; 169) 'gen': fn gen<U>() -> *mut [T;_]
+    [166; 171) 'gen()': *mut [U;_]
+    [186; 420) '{     ...rr); }': ()
+    [196; 199) 'arr': &[u8;_]
+    [212; 216) '&[1]': &[u8;_]
+    [213; 216) '[1]': [u8;_]
+    [214; 215) '1': u8
+    [227; 228) 'a': &[u8]
+    [237; 240) 'arr': &[u8;_]
+    [250; 251) 'b': u8
+    [254; 255) 'f': fn f<u8>(&[T]) -> T
+    [254; 260) 'f(arr)': u8
+    [256; 259) 'arr': &[u8;_]
+    [270; 271) 'c': &[u8]
+    [280; 287) '{ arr }': &[u8]
+    [282; 285) 'arr': &[u8;_]
+    [297; 298) 'd': u8
+    [301; 302) 'g': fn g<u8>(S<&[T]>) -> T
+    [301; 316) 'g(S { a: arr })': u8
+    [303; 315) 'S { a: arr }': S<&[u8]>
+    [310; 313) 'arr': &[u8;_]
+    [326; 327) 'e': [&[u8];_]
+    [341; 346) '[arr]': [&[u8];_]
+    [342; 345) 'arr': &[u8;_]
+    [356; 357) 'f': [&[u8];_]
+    [371; 379) '[arr; 2]': [&[u8];_]
+    [372; 375) 'arr': &[u8;_]
+    [377; 378) '2': usize
+    [389; 390) 'g': (&[u8], &[u8])
+    [407; 417) '(arr, arr)': (&[u8], &[u8])
+    [408; 411) 'arr': &[u8;_]
+    [413; 416) 'arr': &[u8;_]
+    "###
+    );
+}
+
+#[test]
+fn infer_let_stmt_coerce() {
+    assert_snapshot!(
+        infer(r#"
+fn test() {
+    let x: &[i32] = &[1];
+}
+"#),
+        @r###"
+    [11; 40) '{     ...[1]; }': ()
+    [21; 22) 'x': &[i32]
+    [33; 37) '&[1]': &[i32;_]
+    [34; 37) '[1]': [i32;_]
+    [35; 36) '1': i32
+    "###);
+}
+
+#[test]
+fn infer_custom_coerce_unsized() {
+    assert_snapshot!(
+        infer(r#"
+struct A<T: ?Sized>(*const T);
+struct B<T: ?Sized>(*const T);
+struct C<T: ?Sized> { inner: *const T }
+
+impl<T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<B<U>> for B<T> {}
+impl<T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<C<U>> for C<T> {}
+
+fn foo1<T>(x: A<[T]>) -> A<[T]> { x }
+fn foo2<T>(x: B<[T]>) -> B<[T]> { x }
+fn foo3<T>(x: C<[T]>) -> C<[T]> { x }
+
+fn test(a: A<[u8; 2]>, b: B<[u8; 2]>, c: C<[u8; 2]>) {
+    let d = foo1(a);
+    let e = foo2(b);
+    let f = foo3(c);
+}
+"#),
+        @r###"
+    [258; 259) 'x': A<[T]>
+    [279; 284) '{ x }': A<[T]>
+    [281; 282) 'x': A<[T]>
+    [296; 297) 'x': B<[T]>
+    [317; 322) '{ x }': B<[T]>
+    [319; 320) 'x': B<[T]>
+    [334; 335) 'x': C<[T]>
+    [355; 360) '{ x }': C<[T]>
+    [357; 358) 'x': C<[T]>
+    [370; 371) 'a': A<[u8;_]>
+    [385; 386) 'b': B<[u8;_]>
+    [400; 401) 'c': C<[u8;_]>
+    [415; 481) '{     ...(c); }': ()
+    [425; 426) 'd': A<[{unknown}]>
+    [429; 433) 'foo1': fn foo1<{unknown}>(A<[T]>) -> A<[T]>
+    [429; 436) 'foo1(a)': A<[{unknown}]>
+    [434; 435) 'a': A<[u8;_]>
+    [446; 447) 'e': B<[u8]>
+    [450; 454) 'foo2': fn foo2<u8>(B<[T]>) -> B<[T]>
+    [450; 457) 'foo2(b)': B<[u8]>
+    [455; 456) 'b': B<[u8;_]>
+    [467; 468) 'f': C<[u8]>
+    [471; 475) 'foo3': fn foo3<u8>(C<[T]>) -> C<[T]>
+    [471; 478) 'foo3(c)': C<[u8]>
+    [476; 477) 'c': C<[u8;_]>
+    "###
+    );
+}
+
+#[test]
+fn infer_if_coerce() {
+    assert_snapshot!(
+        infer(r#"
+fn foo<T>(x: &[T]) -> &[T] { loop {} }
+fn test() {
+    let x = if true {
+        foo(&[1])
+    } else {
+        &[1]
+    };
+}
+"#),
+        @r###"
+    [11; 12) 'x': &[T]
+    [28; 39) '{ loop {} }': &[T]
+    [30; 37) 'loop {}': !
+    [35; 37) '{}': ()
+    [50; 126) '{     ...  }; }': ()
+    [60; 61) 'x': &[i32]
+    [64; 123) 'if tru...     }': &[i32]
+    [67; 71) 'true': bool
+    [72; 97) '{     ...     }': &[i32]
+    [82; 85) 'foo': fn foo<i32>(&[T]) -> &[T]
+    [82; 91) 'foo(&[1])': &[i32]
+    [86; 90) '&[1]': &[i32;_]
+    [87; 90) '[1]': [i32;_]
+    [88; 89) '1': i32
+    [103; 123) '{     ...     }': &[i32;_]
+    [113; 117) '&[1]': &[i32;_]
+    [114; 117) '[1]': [i32;_]
+    [115; 116) '1': i32
+    "###
+    );
+}
+
+#[test]
+fn infer_if_else_coerce() {
+    assert_snapshot!(
+        infer(r#"
+fn foo<T>(x: &[T]) -> &[T] { loop {} }
+fn test() {
+    let x = if true {
+        &[1]
+    } else {
+        foo(&[1])
+    };
+}
+"#),
+        @r###"
+    [11; 12) 'x': &[T]
+    [28; 39) '{ loop {} }': &[T]
+    [30; 37) 'loop {}': !
+    [35; 37) '{}': ()
+    [50; 126) '{     ...  }; }': ()
+    [60; 61) 'x': &[i32]
+    [64; 123) 'if tru...     }': &[i32]
+    [67; 71) 'true': bool
+    [72; 92) '{     ...     }': &[i32;_]
+    [82; 86) '&[1]': &[i32;_]
+    [83; 86) '[1]': [i32;_]
+    [84; 85) '1': i32
+    [98; 123) '{     ...     }': &[i32]
+    [108; 111) 'foo': fn foo<i32>(&[T]) -> &[T]
+    [108; 117) 'foo(&[1])': &[i32]
+    [112; 116) '&[1]': &[i32;_]
+    [113; 116) '[1]': [i32;_]
+    [114; 115) '1': i32
+    "###
+    );
+}
+
+#[test]
+fn infer_match_first_coerce() {
+    assert_snapshot!(
+        infer(r#"
+fn foo<T>(x: &[T]) -> &[T] { loop {} }
+fn test(i: i32) {
+    let x = match i {
+        2 => foo(&[2]),
+        1 => &[1],
+        _ => &[3],
+    };
+}
+"#),
+        @r###"
+    [11; 12) 'x': &[T]
+    [28; 39) '{ loop {} }': &[T]
+    [30; 37) 'loop {}': !
+    [35; 37) '{}': ()
+    [48; 49) 'i': i32
+    [56; 150) '{     ...  }; }': ()
+    [66; 67) 'x': &[i32]
+    [70; 147) 'match ...     }': &[i32]
+    [76; 77) 'i': i32
+    [88; 89) '2': i32
+    [93; 96) 'foo': fn foo<i32>(&[T]) -> &[T]
+    [93; 102) 'foo(&[2])': &[i32]
+    [97; 101) '&[2]': &[i32;_]
+    [98; 101) '[2]': [i32;_]
+    [99; 100) '2': i32
+    [112; 113) '1': i32
+    [117; 121) '&[1]': &[i32;_]
+    [118; 121) '[1]': [i32;_]
+    [119; 120) '1': i32
+    [131; 132) '_': i32
+    [136; 140) '&[3]': &[i32;_]
+    [137; 140) '[3]': [i32;_]
+    [138; 139) '3': i32
+    "###
+    );
+}
+
+#[test]
+fn infer_match_second_coerce() {
+    assert_snapshot!(
+        infer(r#"
+fn foo<T>(x: &[T]) -> &[T] { loop {} }
+fn test(i: i32) {
+    let x = match i {
+        1 => &[1],
+        2 => foo(&[2]),
+        _ => &[3],
+    };
+}
+"#),
+        @r###"
+    [11; 12) 'x': &[T]
+    [28; 39) '{ loop {} }': &[T]
+    [30; 37) 'loop {}': !
+    [35; 37) '{}': ()
+    [48; 49) 'i': i32
+    [56; 150) '{     ...  }; }': ()
+    [66; 67) 'x': &[i32]
+    [70; 147) 'match ...     }': &[i32]
+    [76; 77) 'i': i32
+    [88; 89) '1': i32
+    [93; 97) '&[1]': &[i32;_]
+    [94; 97) '[1]': [i32;_]
+    [95; 96) '1': i32
+    [107; 108) '2': i32
+    [112; 115) 'foo': fn foo<i32>(&[T]) -> &[T]
+    [112; 121) 'foo(&[2])': &[i32]
+    [116; 120) '&[2]': &[i32;_]
+    [117; 120) '[2]': [i32;_]
+    [118; 119) '2': i32
+    [131; 132) '_': i32
+    [136; 140) '&[3]': &[i32;_]
+    [137; 140) '[3]': [i32;_]
+    [138; 139) '3': i32
+    "###
+    );
+}
+
+#[test]
+fn coerce_merge_one_by_one1() {
+    covers!(coerce_merge_fail_fallback);
+
+    assert_snapshot!(
+        infer(r#"
+fn test() {
+    let t = &mut 1;
+    let x = match 1 {
+        1 => t as *mut i32,
+        2 => t as &i32,
+        _ => t as *const i32,
+    };
+}
+"#),
+        @r###"
+    [11; 145) '{     ...  }; }': ()
+    [21; 22) 't': &mut i32
+    [25; 31) '&mut 1': &mut i32
+    [30; 31) '1': i32
+    [41; 42) 'x': *const i32
+    [45; 142) 'match ...     }': *const i32
+    [51; 52) '1': i32
+    [63; 64) '1': i32
+    [68; 69) 't': &mut i32
+    [68; 81) 't as *mut i32': *mut i32
+    [91; 92) '2': i32
+    [96; 97) 't': &mut i32
+    [96; 105) 't as &i32': &i32
+    [115; 116) '_': i32
+    [120; 121) 't': &mut i32
+    [120; 135) 't as *const i32': *const i32
+    "###
+    );
+}
diff --git a/crates/ra_hir_ty/src/tests/never_type.rs b/crates/ra_hir_ty/src/tests/never_type.rs
new file mode 100644
index 000000000..c202f545a
--- /dev/null
+++ b/crates/ra_hir_ty/src/tests/never_type.rs
@@ -0,0 +1,246 @@
+use super::type_at;
+
+#[test]
+fn infer_never1() {
+    let t = type_at(
+        r#"
+//- /main.rs
+fn test() {
+    let t = return;
+    t<|>;
+}
+"#,
+    );
+    assert_eq!(t, "!");
+}
+
+#[test]
+fn infer_never2() {
+    let t = type_at(
+        r#"
+//- /main.rs
+fn gen<T>() -> T { loop {} }
+
+fn test() {
+    let a = gen();
+    if false { a } else { loop {} };
+    a<|>;
+}
+"#,
+    );
+    assert_eq!(t, "!");
+}
+
+#[test]
+fn infer_never3() {
+    let t = type_at(
+        r#"
+//- /main.rs
+fn gen<T>() -> T { loop {} }
+
+fn test() {
+    let a = gen();
+    if false { loop {} } else { a };
+    a<|>;
+}
+"#,
+    );
+    assert_eq!(t, "!");
+}
+
+#[test]
+fn never_type_in_generic_args() {
+    let t = type_at(
+        r#"
+//- /main.rs
+enum Option<T> { None, Some(T) }
+
+fn test() {
+    let a = if true { Option::None } else { Option::Some(return) };
+    a<|>;
+}
+"#,
+    );
+    assert_eq!(t, "Option<!>");
+}
+
+#[test]
+fn never_type_can_be_reinferred1() {
+    let t = type_at(
+        r#"
+//- /main.rs
+fn gen<T>() -> T { loop {} }
+
+fn test() {
+    let a = gen();
+    if false { loop {} } else { a };
+    a<|>;
+    if false { a };
+}
+"#,
+    );
+    assert_eq!(t, "()");
+}
+
+#[test]
+fn never_type_can_be_reinferred2() {
+    let t = type_at(
+        r#"
+//- /main.rs
+enum Option<T> { None, Some(T) }
+
+fn test() {
+    let a = if true { Option::None } else { Option::Some(return) };
+    a<|>;
+    match 42 {
+        42 => a,
+        _ => Option::Some(42),
+    };
+}
+"#,
+    );
+    assert_eq!(t, "Option<i32>");
+}
+#[test]
+fn never_type_can_be_reinferred3() {
+    let t = type_at(
+        r#"
+//- /main.rs
+enum Option<T> { None, Some(T) }
+
+fn test() {
+    let a = if true { Option::None } else { Option::Some(return) };
+    a<|>;
+    match 42 {
+        42 => a,
+        _ => Option::Some("str"),
+    };
+}
+"#,
+    );
+    assert_eq!(t, "Option<&str>");
+}
+
+#[test]
+fn match_no_arm() {
+    let t = type_at(
+        r#"
+//- /main.rs
+enum Void {}
+
+fn test(a: Void) {
+    let t = match a {};
+    t<|>;
+}
+"#,
+    );
+    assert_eq!(t, "!");
+}
+
+#[test]
+fn if_never() {
+    let t = type_at(
+        r#"
+//- /main.rs
+fn test() {
+    let i = if true {
+        loop {}
+    } else {
+        3.0
+    };
+    i<|>;
+}
+"#,
+    );
+    assert_eq!(t, "f64");
+}
+
+#[test]
+fn if_else_never() {
+    let t = type_at(
+        r#"
+//- /main.rs
+fn test(input: bool) {
+    let i = if input {
+        2.0
+    } else {
+        return
+    };
+    i<|>;
+}
+"#,
+    );
+    assert_eq!(t, "f64");
+}
+
+#[test]
+fn match_first_arm_never() {
+    let t = type_at(
+        r#"
+//- /main.rs
+fn test(a: i32) {
+    let i = match a {
+        1 => return,
+        2 => 2.0,
+        3 => loop {},
+        _ => 3.0,
+    };
+    i<|>;
+}
+"#,
+    );
+    assert_eq!(t, "f64");
+}
+
+#[test]
+fn match_second_arm_never() {
+    let t = type_at(
+        r#"
+//- /main.rs
+fn test(a: i32) {
+    let i = match a {
+        1 => 3.0,
+        2 => loop {},
+        3 => 3.0,
+        _ => return,
+    };
+    i<|>;
+}
+"#,
+    );
+    assert_eq!(t, "f64");
+}
+
+#[test]
+fn match_all_arms_never() {
+    let t = type_at(
+        r#"
+//- /main.rs
+fn test(a: i32) {
+    let i = match a {
+        2 => return,
+        _ => loop {},
+    };
+    i<|>;
+}
+"#,
+    );
+    assert_eq!(t, "!");
+}
+
+#[test]
+fn match_no_never_arms() {
+    let t = type_at(
+        r#"
+//- /main.rs
+fn test(a: i32) {
+    let i = match a {
+        2 => 2.0,
+        _ => 3.0,
+    };
+    i<|>;
+}
+"#,
+    );
+    assert_eq!(t, "f64");
+}
diff --git a/crates/ra_hir_ty/src/traits.rs b/crates/ra_hir_ty/src/traits.rs
new file mode 100644
index 000000000..76189a60b
--- /dev/null
+++ b/crates/ra_hir_ty/src/traits.rs
@@ -0,0 +1,328 @@
+//! Trait solving using Chalk.
+use std::sync::{Arc, Mutex};
+
+use chalk_ir::{cast::Cast, family::ChalkIr};
+use hir_def::{expr::ExprId, DefWithBodyId, ImplId, TraitId, TypeAliasId};
+use log::debug;
+use ra_db::{impl_intern_key, salsa, CrateId};
+use ra_prof::profile;
+use rustc_hash::FxHashSet;
+
+use crate::db::HirDatabase;
+
+use super::{Canonical, GenericPredicate, HirDisplay, ProjectionTy, TraitRef, Ty, TypeWalk};
+
+use self::chalk::{from_chalk, ToChalk};
+
+pub(crate) mod chalk;
+
+#[derive(Debug, Clone)]
+pub struct TraitSolver {
+    krate: CrateId,
+    inner: Arc<Mutex<chalk_solve::Solver<ChalkIr>>>,
+}
+
+/// We need eq for salsa
+impl PartialEq for TraitSolver {
+    fn eq(&self, other: &TraitSolver) -> bool {
+        Arc::ptr_eq(&self.inner, &other.inner)
+    }
+}
+
+impl Eq for TraitSolver {}
+
+impl TraitSolver {
+    fn solve(
+        &self,
+        db: &impl HirDatabase,
+        goal: &chalk_ir::UCanonical<chalk_ir::InEnvironment<chalk_ir::Goal<ChalkIr>>>,
+    ) -> Option<chalk_solve::Solution<ChalkIr>> {
+        let context = ChalkContext { db, krate: self.krate };
+        debug!("solve goal: {:?}", goal);
+        let mut solver = match self.inner.lock() {
+            Ok(it) => it,
+            // Our cancellation works via unwinding, but, as chalk is not
+            // panic-safe, we need to make sure to propagate the cancellation.
+            // Ideally, we should also make chalk panic-safe.
+            Err(_) => ra_db::Canceled::throw(),
+        };
+        let solution = solver.solve(&context, goal);
+        debug!("solve({:?}) => {:?}", goal, solution);
+        solution
+    }
+}
+
+/// This controls the maximum size of types Chalk considers. If we set this too
+/// high, we can run into slow edge cases; if we set it too low, Chalk won't
+/// find some solutions.
+const CHALK_SOLVER_MAX_SIZE: usize = 4;
+
+#[derive(Debug, Copy, Clone)]
+struct ChalkContext<'a, DB> {
+    db: &'a DB,
+    krate: CrateId,
+}
+
+pub(crate) fn trait_solver_query(
+    db: &(impl HirDatabase + salsa::Database),
+    krate: CrateId,
+) -> TraitSolver {
+    db.salsa_runtime().report_untracked_read();
+    // krate parameter is just so we cache a unique solver per crate
+    let solver_choice = chalk_solve::SolverChoice::SLG { max_size: CHALK_SOLVER_MAX_SIZE };
+    debug!("Creating new solver for crate {:?}", krate);
+    TraitSolver { krate, inner: Arc::new(Mutex::new(solver_choice.into_solver())) }
+}
+
+/// Collects impls for the given trait in the whole dependency tree of `krate`.
+pub(crate) fn impls_for_trait_query(
+    db: &impl HirDatabase,
+    krate: CrateId,
+    trait_: TraitId,
+) -> Arc<[ImplId]> {
+    let mut impls = FxHashSet::default();
+    // We call the query recursively here. On the one hand, this means we can
+    // reuse results from queries for different crates; on the other hand, this
+    // will only ever get called for a few crates near the root of the tree (the
+    // ones the user is editing), so this may actually be a waste of memory. I'm
+    // doing it like this mainly for simplicity for now.
+    for dep in db.crate_graph().dependencies(krate) {
+        impls.extend(db.impls_for_trait(dep.crate_id, trait_).iter());
+    }
+    let crate_impl_blocks = db.impls_in_crate(krate);
+    impls.extend(crate_impl_blocks.lookup_impl_blocks_for_trait(trait_));
+    impls.into_iter().collect()
+}
+
+/// A set of clauses that we assume to be true. E.g. if we are inside this function:
+/// ```rust
+/// fn foo<T: Default>(t: T) {}
+/// ```
+/// we assume that `T: Default`.
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct TraitEnvironment {
+    pub predicates: Vec<GenericPredicate>,
+}
+
+impl TraitEnvironment {
+    /// Returns trait refs with the given self type which are supposed to hold
+    /// in this trait env. E.g. if we are in `foo<T: SomeTrait>()`, this will
+    /// find that `T: SomeTrait` if we call it for `T`.
+    pub(crate) fn trait_predicates_for_self_ty<'a>(
+        &'a self,
+        ty: &'a Ty,
+    ) -> impl Iterator<Item = &'a TraitRef> + 'a {
+        self.predicates.iter().filter_map(move |pred| match pred {
+            GenericPredicate::Implemented(tr) if tr.self_ty() == ty => Some(tr),
+            _ => None,
+        })
+    }
+}
+
+/// Something (usually a goal), along with an environment.
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct InEnvironment<T> {
+    pub environment: Arc<TraitEnvironment>,
+    pub value: T,
+}
+
+impl<T> InEnvironment<T> {
+    pub fn new(environment: Arc<TraitEnvironment>, value: T) -> InEnvironment<T> {
+        InEnvironment { environment, value }
+    }
+}
+
+/// Something that needs to be proven (by Chalk) during type checking, e.g. that
+/// a certain type implements a certain trait. Proving the Obligation might
+/// result in additional information about inference variables.
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub enum Obligation {
+    /// Prove that a certain type implements a trait (the type is the `Self` type
+    /// parameter to the `TraitRef`).
+    Trait(TraitRef),
+    Projection(ProjectionPredicate),
+}
+
+impl Obligation {
+    pub fn from_predicate(predicate: GenericPredicate) -> Option<Obligation> {
+        match predicate {
+            GenericPredicate::Implemented(trait_ref) => Some(Obligation::Trait(trait_ref)),
+            GenericPredicate::Projection(projection_pred) => {
+                Some(Obligation::Projection(projection_pred))
+            }
+            GenericPredicate::Error => None,
+        }
+    }
+}
+
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct ProjectionPredicate {
+    pub projection_ty: ProjectionTy,
+    pub ty: Ty,
+}
+
+impl TypeWalk for ProjectionPredicate {
+    fn walk(&self, f: &mut impl FnMut(&Ty)) {
+        self.projection_ty.walk(f);
+        self.ty.walk(f);
+    }
+
+    fn walk_mut_binders(&mut self, f: &mut impl FnMut(&mut Ty, usize), binders: usize) {
+        self.projection_ty.walk_mut_binders(f, binders);
+        self.ty.walk_mut_binders(f, binders);
+    }
+}
+
+/// Solve a trait goal using Chalk.
+pub(crate) fn trait_solve_query(
+    db: &impl HirDatabase,
+    krate: CrateId,
+    goal: Canonical<InEnvironment<Obligation>>,
+) -> Option<Solution> {
+    let _p = profile("trait_solve_query");
+    debug!("trait_solve_query({})", goal.value.value.display(db));
+
+    if let Obligation::Projection(pred) = &goal.value.value {
+        if let Ty::Bound(_) = &pred.projection_ty.parameters[0] {
+            // Hack: don't ask Chalk to normalize with an unknown self type, it'll say that's impossible
+            return Some(Solution::Ambig(Guidance::Unknown));
+        }
+    }
+
+    let canonical = goal.to_chalk(db).cast();
+
+    // We currently don't deal with universes (I think / hope they're not yet
+    // relevant for our use cases?)
+    let u_canonical = chalk_ir::UCanonical { canonical, universes: 1 };
+    let solution = db.trait_solver(krate).solve(db, &u_canonical);
+    solution.map(|solution| solution_from_chalk(db, solution))
+}
+
+fn solution_from_chalk(
+    db: &impl HirDatabase,
+    solution: chalk_solve::Solution<ChalkIr>,
+) -> Solution {
+    let convert_subst = |subst: chalk_ir::Canonical<chalk_ir::Substitution<ChalkIr>>| {
+        let value = subst
+            .value
+            .parameters
+            .into_iter()
+            .map(|p| {
+                let ty = match p {
+                    chalk_ir::Parameter(chalk_ir::ParameterKind::Ty(ty)) => from_chalk(db, ty),
+                    chalk_ir::Parameter(chalk_ir::ParameterKind::Lifetime(_)) => unimplemented!(),
+                };
+                ty
+            })
+            .collect();
+        let result = Canonical { value, num_vars: subst.binders.len() };
+        SolutionVariables(result)
+    };
+    match solution {
+        chalk_solve::Solution::Unique(constr_subst) => {
+            let subst = chalk_ir::Canonical {
+                value: constr_subst.value.subst,
+                binders: constr_subst.binders,
+            };
+            Solution::Unique(convert_subst(subst))
+        }
+        chalk_solve::Solution::Ambig(chalk_solve::Guidance::Definite(subst)) => {
+            Solution::Ambig(Guidance::Definite(convert_subst(subst)))
+        }
+        chalk_solve::Solution::Ambig(chalk_solve::Guidance::Suggested(subst)) => {
+            Solution::Ambig(Guidance::Suggested(convert_subst(subst)))
+        }
+        chalk_solve::Solution::Ambig(chalk_solve::Guidance::Unknown) => {
+            Solution::Ambig(Guidance::Unknown)
+        }
+    }
+}
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct SolutionVariables(pub Canonical<Vec<Ty>>);
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+/// A (possible) solution for a proposed goal.
+pub enum Solution {
+    /// The goal indeed holds, and there is a unique value for all existential
+    /// variables.
+    Unique(SolutionVariables),
+
+    /// The goal may be provable in multiple ways, but regardless we may have some guidance
+    /// for type inference. In this case, we don't return any lifetime
+    /// constraints, since we have not "committed" to any particular solution
+    /// yet.
+    Ambig(Guidance),
+}
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+/// When a goal holds ambiguously (e.g., because there are multiple possible
+/// solutions), we issue a set of *guidance* back to type inference.
+pub enum Guidance {
+    /// The existential variables *must* have the given values if the goal is
+    /// ever to hold, but that alone isn't enough to guarantee the goal will
+    /// actually hold.
+    Definite(SolutionVariables),
+
+    /// There are multiple plausible values for the existentials, but the ones
+    /// here are suggested as the preferred choice heuristically. These should
+    /// be used for inference fallback only.
+    Suggested(SolutionVariables),
+
+    /// There's no useful information to feed back to type inference
+    Unknown,
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
+pub enum FnTrait {
+    FnOnce,
+    FnMut,
+    Fn,
+}
+
+impl FnTrait {
+    fn lang_item_name(self) -> &'static str {
+        match self {
+            FnTrait::FnOnce => "fn_once",
+            FnTrait::FnMut => "fn_mut",
+            FnTrait::Fn => "fn",
+        }
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub struct ClosureFnTraitImplData {
+    def: DefWithBodyId,
+    expr: ExprId,
+    fn_trait: FnTrait,
+}
+
+/// An impl. Usually this comes from an impl block, but some built-in types get
+/// synthetic impls.
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub enum Impl {
+    /// A normal impl from an impl block.
+    ImplBlock(ImplId),
+    /// Closure types implement the Fn traits synthetically.
+    ClosureFnTraitImpl(ClosureFnTraitImplData),
+}
+/// This exists just for Chalk, because our ImplIds are only unique per module.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct GlobalImplId(salsa::InternId);
+impl_intern_key!(GlobalImplId);
+
+/// An associated type value. Usually this comes from a `type` declaration
+/// inside an impl block, but for built-in impls we have to synthesize it.
+/// (We only need this because Chalk wants a unique ID for each of these.)
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub enum AssocTyValue {
+    /// A normal assoc type value from an impl block.
+    TypeAlias(TypeAliasId),
+    /// The output type of the Fn trait implementation.
+    ClosureFnTraitImplOutput(ClosureFnTraitImplData),
+}
+/// This exists just for Chalk, because it needs a unique ID for each associated
+/// type value in an impl (even synthetic ones).
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct AssocTyValueId(salsa::InternId);
+impl_intern_key!(AssocTyValueId);
diff --git a/crates/ra_hir_ty/src/traits/chalk.rs b/crates/ra_hir_ty/src/traits/chalk.rs
new file mode 100644
index 000000000..35de37e6b
--- /dev/null
+++ b/crates/ra_hir_ty/src/traits/chalk.rs
@@ -0,0 +1,900 @@
+//! Conversion code from/to Chalk.
+use std::sync::Arc;
+
+use log::debug;
+
+use chalk_ir::{
+    cast::Cast, family::ChalkIr, Identifier, Parameter, PlaceholderIndex, TypeId, TypeKindId,
+    TypeName, UniverseIndex,
+};
+use chalk_rust_ir::{AssociatedTyDatum, AssociatedTyValue, ImplDatum, StructDatum, TraitDatum};
+use ra_db::CrateId;
+
+use hir_def::{
+    expr::Expr, lang_item::LangItemTarget, AssocItemId, AstItemDef, ContainerId, GenericDefId,
+    ImplId, Lookup, TraitId, TypeAliasId,
+};
+use hir_expand::name;
+
+use ra_db::salsa::{InternId, InternKey};
+
+use super::{AssocTyValue, Canonical, ChalkContext, Impl, Obligation};
+use crate::{
+    db::HirDatabase, display::HirDisplay, ApplicationTy, GenericPredicate, ImplTy, ProjectionTy,
+    Substs, TraitRef, Ty, TypeCtor, TypeWalk,
+};
+
+/// This represents a trait whose name we could not resolve.
+const UNKNOWN_TRAIT: chalk_ir::TraitId =
+    chalk_ir::TraitId(chalk_ir::RawId { index: u32::max_value() });
+
+pub(super) trait ToChalk {
+    type Chalk;
+    fn to_chalk(self, db: &impl HirDatabase) -> Self::Chalk;
+    fn from_chalk(db: &impl HirDatabase, chalk: Self::Chalk) -> Self;
+}
+
+pub(super) fn from_chalk<T, ChalkT>(db: &impl HirDatabase, chalk: ChalkT) -> T
+where
+    T: ToChalk<Chalk = ChalkT>,
+{
+    T::from_chalk(db, chalk)
+}
+
+impl ToChalk for Ty {
+    type Chalk = chalk_ir::Ty<ChalkIr>;
+    fn to_chalk(self, db: &impl HirDatabase) -> chalk_ir::Ty<ChalkIr> {
+        match self {
+            Ty::Apply(apply_ty) => {
+                let name = match apply_ty.ctor {
+                    TypeCtor::AssociatedType(type_alias) => {
+                        let type_id = type_alias.to_chalk(db);
+                        TypeName::AssociatedType(type_id)
+                    }
+                    _ => {
+                        // other TypeCtors get interned and turned into a chalk StructId
+                        let struct_id = apply_ty.ctor.to_chalk(db);
+                        TypeName::TypeKindId(struct_id.into())
+                    }
+                };
+                let parameters = apply_ty.parameters.to_chalk(db);
+                chalk_ir::ApplicationTy { name, parameters }.cast().intern()
+            }
+            Ty::Projection(proj_ty) => {
+                let associated_ty_id = proj_ty.associated_ty.to_chalk(db);
+                let parameters = proj_ty.parameters.to_chalk(db);
+                chalk_ir::ProjectionTy { associated_ty_id, parameters }.cast().intern()
+            }
+            Ty::Param { idx, .. } => {
+                PlaceholderIndex { ui: UniverseIndex::ROOT, idx: idx as usize }.to_ty::<ChalkIr>()
+            }
+            Ty::Bound(idx) => chalk_ir::TyData::BoundVar(idx as usize).intern(),
+            Ty::Infer(_infer_ty) => panic!("uncanonicalized infer ty"),
+            Ty::Dyn(predicates) => {
+                let where_clauses = predicates.iter().cloned().map(|p| p.to_chalk(db)).collect();
+                chalk_ir::TyData::Dyn(make_binders(where_clauses, 1)).intern()
+            }
+            Ty::Opaque(predicates) => {
+                let where_clauses = predicates.iter().cloned().map(|p| p.to_chalk(db)).collect();
+                chalk_ir::TyData::Opaque(make_binders(where_clauses, 1)).intern()
+            }
+            Ty::Unknown => {
+                let parameters = Vec::new();
+                let name = TypeName::Error;
+                chalk_ir::ApplicationTy { name, parameters }.cast().intern()
+            }
+        }
+    }
+    fn from_chalk(db: &impl HirDatabase, chalk: chalk_ir::Ty<ChalkIr>) -> Self {
+        match chalk.data().clone() {
+            chalk_ir::TyData::Apply(apply_ty) => {
+                // FIXME this is kind of hacky due to the fact that
+                // TypeName::Placeholder is a Ty::Param on our side
+                match apply_ty.name {
+                    TypeName::TypeKindId(TypeKindId::StructId(struct_id)) => {
+                        let ctor = from_chalk(db, struct_id);
+                        let parameters = from_chalk(db, apply_ty.parameters);
+                        Ty::Apply(ApplicationTy { ctor, parameters })
+                    }
+                    TypeName::AssociatedType(type_id) => {
+                        let ctor = TypeCtor::AssociatedType(from_chalk(db, type_id));
+                        let parameters = from_chalk(db, apply_ty.parameters);
+                        Ty::Apply(ApplicationTy { ctor, parameters })
+                    }
+                    TypeName::Error => Ty::Unknown,
+                    // FIXME handle TypeKindId::Trait/Type here
+                    TypeName::TypeKindId(_) => unimplemented!(),
+                    TypeName::Placeholder(idx) => {
+                        assert_eq!(idx.ui, UniverseIndex::ROOT);
+                        Ty::Param { idx: idx.idx as u32, name: crate::Name::missing() }
+                    }
+                }
+            }
+            chalk_ir::TyData::Projection(proj) => {
+                let associated_ty = from_chalk(db, proj.associated_ty_id);
+                let parameters = from_chalk(db, proj.parameters);
+                Ty::Projection(ProjectionTy { associated_ty, parameters })
+            }
+            chalk_ir::TyData::ForAll(_) => unimplemented!(),
+            chalk_ir::TyData::BoundVar(idx) => Ty::Bound(idx as u32),
+            chalk_ir::TyData::InferenceVar(_iv) => Ty::Unknown,
+            chalk_ir::TyData::Dyn(where_clauses) => {
+                assert_eq!(where_clauses.binders.len(), 1);
+                let predicates =
+                    where_clauses.value.into_iter().map(|c| from_chalk(db, c)).collect();
+                Ty::Dyn(predicates)
+            }
+            chalk_ir::TyData::Opaque(where_clauses) => {
+                assert_eq!(where_clauses.binders.len(), 1);
+                let predicates =
+                    where_clauses.value.into_iter().map(|c| from_chalk(db, c)).collect();
+                Ty::Opaque(predicates)
+            }
+        }
+    }
+}
+
+impl ToChalk for Substs {
+    type Chalk = Vec<chalk_ir::Parameter<ChalkIr>>;
+
+    fn to_chalk(self, db: &impl HirDatabase) -> Vec<Parameter<ChalkIr>> {
+        self.iter().map(|ty| ty.clone().to_chalk(db).cast()).collect()
+    }
+
+    fn from_chalk(db: &impl HirDatabase, parameters: Vec<chalk_ir::Parameter<ChalkIr>>) -> Substs {
+        let tys = parameters
+            .into_iter()
+            .map(|p| match p {
+                chalk_ir::Parameter(chalk_ir::ParameterKind::Ty(ty)) => from_chalk(db, ty),
+                chalk_ir::Parameter(chalk_ir::ParameterKind::Lifetime(_)) => unimplemented!(),
+            })
+            .collect();
+        Substs(tys)
+    }
+}
+
+impl ToChalk for TraitRef {
+    type Chalk = chalk_ir::TraitRef<ChalkIr>;
+
+    fn to_chalk(self: TraitRef, db: &impl HirDatabase) -> chalk_ir::TraitRef<ChalkIr> {
+        let trait_id = self.trait_.to_chalk(db);
+        let parameters = self.substs.to_chalk(db);
+        chalk_ir::TraitRef { trait_id, parameters }
+    }
+
+    fn from_chalk(db: &impl HirDatabase, trait_ref: chalk_ir::TraitRef<ChalkIr>) -> Self {
+        let trait_ = from_chalk(db, trait_ref.trait_id);
+        let substs = from_chalk(db, trait_ref.parameters);
+        TraitRef { trait_, substs }
+    }
+}
+
+impl ToChalk for TraitId {
+    type Chalk = chalk_ir::TraitId;
+
+    fn to_chalk(self, _db: &impl HirDatabase) -> chalk_ir::TraitId {
+        chalk_ir::TraitId(id_to_chalk(self))
+    }
+
+    fn from_chalk(_db: &impl HirDatabase, trait_id: chalk_ir::TraitId) -> TraitId {
+        id_from_chalk(trait_id.0)
+    }
+}
+
+impl ToChalk for TypeCtor {
+    type Chalk = chalk_ir::StructId;
+
+    fn to_chalk(self, db: &impl HirDatabase) -> chalk_ir::StructId {
+        db.intern_type_ctor(self).into()
+    }
+
+    fn from_chalk(db: &impl HirDatabase, struct_id: chalk_ir::StructId) -> TypeCtor {
+        db.lookup_intern_type_ctor(struct_id.into())
+    }
+}
+
+impl ToChalk for Impl {
+    type Chalk = chalk_ir::ImplId;
+
+    fn to_chalk(self, db: &impl HirDatabase) -> chalk_ir::ImplId {
+        db.intern_chalk_impl(self).into()
+    }
+
+    fn from_chalk(db: &impl HirDatabase, impl_id: chalk_ir::ImplId) -> Impl {
+        db.lookup_intern_chalk_impl(impl_id.into())
+    }
+}
+
+impl ToChalk for TypeAliasId {
+    type Chalk = chalk_ir::TypeId;
+
+    fn to_chalk(self, _db: &impl HirDatabase) -> chalk_ir::TypeId {
+        chalk_ir::TypeId(id_to_chalk(self))
+    }
+
+    fn from_chalk(_db: &impl HirDatabase, type_alias_id: chalk_ir::TypeId) -> TypeAliasId {
+        id_from_chalk(type_alias_id.0)
+    }
+}
+
+impl ToChalk for AssocTyValue {
+    type Chalk = chalk_rust_ir::AssociatedTyValueId;
+
+    fn to_chalk(self, db: &impl HirDatabase) -> chalk_rust_ir::AssociatedTyValueId {
+        db.intern_assoc_ty_value(self).into()
+    }
+
+    fn from_chalk(
+        db: &impl HirDatabase,
+        assoc_ty_value_id: chalk_rust_ir::AssociatedTyValueId,
+    ) -> AssocTyValue {
+        db.lookup_intern_assoc_ty_value(assoc_ty_value_id.into())
+    }
+}
+
+impl ToChalk for GenericPredicate {
+    type Chalk = chalk_ir::QuantifiedWhereClause<ChalkIr>;
+
+    fn to_chalk(self, db: &impl HirDatabase) -> chalk_ir::QuantifiedWhereClause<ChalkIr> {
+        match self {
+            GenericPredicate::Implemented(trait_ref) => {
+                make_binders(chalk_ir::WhereClause::Implemented(trait_ref.to_chalk(db)), 0)
+            }
+            GenericPredicate::Projection(projection_pred) => make_binders(
+                chalk_ir::WhereClause::ProjectionEq(chalk_ir::ProjectionEq {
+                    projection: projection_pred.projection_ty.to_chalk(db),
+                    ty: projection_pred.ty.to_chalk(db),
+                }),
+                0,
+            ),
+            GenericPredicate::Error => {
+                let impossible_trait_ref = chalk_ir::TraitRef {
+                    trait_id: UNKNOWN_TRAIT,
+                    parameters: vec![Ty::Unknown.to_chalk(db).cast()],
+                };
+                make_binders(chalk_ir::WhereClause::Implemented(impossible_trait_ref), 0)
+            }
+        }
+    }
+
+    fn from_chalk(
+        db: &impl HirDatabase,
+        where_clause: chalk_ir::QuantifiedWhereClause<ChalkIr>,
+    ) -> GenericPredicate {
+        match where_clause.value {
+            chalk_ir::WhereClause::Implemented(tr) => {
+                if tr.trait_id == UNKNOWN_TRAIT {
+                    // FIXME we need an Error enum on the Chalk side to avoid this
+                    return GenericPredicate::Error;
+                }
+                GenericPredicate::Implemented(from_chalk(db, tr))
+            }
+            chalk_ir::WhereClause::ProjectionEq(projection_eq) => {
+                let projection_ty = from_chalk(db, projection_eq.projection);
+                let ty = from_chalk(db, projection_eq.ty);
+                GenericPredicate::Projection(super::ProjectionPredicate { projection_ty, ty })
+            }
+        }
+    }
+}
+
+impl ToChalk for ProjectionTy {
+    type Chalk = chalk_ir::ProjectionTy<ChalkIr>;
+
+    fn to_chalk(self, db: &impl HirDatabase) -> chalk_ir::ProjectionTy<ChalkIr> {
+        chalk_ir::ProjectionTy {
+            associated_ty_id: self.associated_ty.to_chalk(db),
+            parameters: self.parameters.to_chalk(db),
+        }
+    }
+
+    fn from_chalk(
+        db: &impl HirDatabase,
+        projection_ty: chalk_ir::ProjectionTy<ChalkIr>,
+    ) -> ProjectionTy {
+        ProjectionTy {
+            associated_ty: from_chalk(db, projection_ty.associated_ty_id),
+            parameters: from_chalk(db, projection_ty.parameters),
+        }
+    }
+}
+
+impl ToChalk for super::ProjectionPredicate {
+    type Chalk = chalk_ir::Normalize<ChalkIr>;
+
+    fn to_chalk(self, db: &impl HirDatabase) -> chalk_ir::Normalize<ChalkIr> {
+        chalk_ir::Normalize {
+            projection: self.projection_ty.to_chalk(db),
+            ty: self.ty.to_chalk(db),
+        }
+    }
+
+    fn from_chalk(_db: &impl HirDatabase, _normalize: chalk_ir::Normalize<ChalkIr>) -> Self {
+        unimplemented!()
+    }
+}
+
+impl ToChalk for Obligation {
+    type Chalk = chalk_ir::DomainGoal<ChalkIr>;
+
+    fn to_chalk(self, db: &impl HirDatabase) -> chalk_ir::DomainGoal<ChalkIr> {
+        match self {
+            Obligation::Trait(tr) => tr.to_chalk(db).cast(),
+            Obligation::Projection(pr) => pr.to_chalk(db).cast(),
+        }
+    }
+
+    fn from_chalk(_db: &impl HirDatabase, _goal: chalk_ir::DomainGoal<ChalkIr>) -> Self {
+        unimplemented!()
+    }
+}
+
+impl<T> ToChalk for Canonical<T>
+where
+    T: ToChalk,
+{
+    type Chalk = chalk_ir::Canonical<T::Chalk>;
+
+    fn to_chalk(self, db: &impl HirDatabase) -> chalk_ir::Canonical<T::Chalk> {
+        let parameter = chalk_ir::ParameterKind::Ty(chalk_ir::UniverseIndex::ROOT);
+        let value = self.value.to_chalk(db);
+        let canonical = chalk_ir::Canonical { value, binders: vec![parameter; self.num_vars] };
+        canonical
+    }
+
+    fn from_chalk(db: &impl HirDatabase, canonical: chalk_ir::Canonical<T::Chalk>) -> Canonical<T> {
+        Canonical { num_vars: canonical.binders.len(), value: from_chalk(db, canonical.value) }
+    }
+}
+
+impl ToChalk for Arc<super::TraitEnvironment> {
+    type Chalk = chalk_ir::Environment<ChalkIr>;
+
+    fn to_chalk(self, db: &impl HirDatabase) -> chalk_ir::Environment<ChalkIr> {
+        let mut clauses = Vec::new();
+        for pred in &self.predicates {
+            if pred.is_error() {
+                // for env, we just ignore errors
+                continue;
+            }
+            let program_clause: chalk_ir::ProgramClause<ChalkIr> = pred.clone().to_chalk(db).cast();
+            clauses.push(program_clause.into_from_env_clause());
+        }
+        chalk_ir::Environment::new().add_clauses(clauses)
+    }
+
+    fn from_chalk(
+        _db: &impl HirDatabase,
+        _env: chalk_ir::Environment<ChalkIr>,
+    ) -> Arc<super::TraitEnvironment> {
+        unimplemented!()
+    }
+}
+
+impl<T: ToChalk> ToChalk for super::InEnvironment<T>
+where
+    T::Chalk: chalk_ir::family::HasTypeFamily<TypeFamily = ChalkIr>,
+{
+    type Chalk = chalk_ir::InEnvironment<T::Chalk>;
+
+    fn to_chalk(self, db: &impl HirDatabase) -> chalk_ir::InEnvironment<T::Chalk> {
+        chalk_ir::InEnvironment {
+            environment: self.environment.to_chalk(db),
+            goal: self.value.to_chalk(db),
+        }
+    }
+
+    fn from_chalk(
+        db: &impl HirDatabase,
+        in_env: chalk_ir::InEnvironment<T::Chalk>,
+    ) -> super::InEnvironment<T> {
+        super::InEnvironment {
+            environment: from_chalk(db, in_env.environment),
+            value: from_chalk(db, in_env.goal),
+        }
+    }
+}
+
+fn make_binders<T>(value: T, num_vars: usize) -> chalk_ir::Binders<T> {
+    chalk_ir::Binders {
+        value,
+        binders: std::iter::repeat(chalk_ir::ParameterKind::Ty(())).take(num_vars).collect(),
+    }
+}
+
+fn convert_where_clauses(
+    db: &impl HirDatabase,
+    def: GenericDefId,
+    substs: &Substs,
+) -> Vec<chalk_ir::QuantifiedWhereClause<ChalkIr>> {
+    let generic_predicates = db.generic_predicates(def);
+    let mut result = Vec::with_capacity(generic_predicates.len());
+    for pred in generic_predicates.iter() {
+        if pred.is_error() {
+            // HACK: Return just the single predicate (which is always false
+            // anyway), otherwise Chalk can easily get into slow situations
+            return vec![pred.clone().subst(substs).to_chalk(db)];
+        }
+        result.push(pred.clone().subst(substs).to_chalk(db));
+    }
+    result
+}
+
+impl<'a, DB> chalk_solve::RustIrDatabase<ChalkIr> for ChalkContext<'a, DB>
+where
+    DB: HirDatabase,
+{
+    fn associated_ty_data(&self, id: TypeId) -> Arc<AssociatedTyDatum<ChalkIr>> {
+        self.db.associated_ty_data(id)
+    }
+    fn trait_datum(&self, trait_id: chalk_ir::TraitId) -> Arc<TraitDatum<ChalkIr>> {
+        self.db.trait_datum(self.krate, trait_id)
+    }
+    fn struct_datum(&self, struct_id: chalk_ir::StructId) -> Arc<StructDatum<ChalkIr>> {
+        self.db.struct_datum(self.krate, struct_id)
+    }
+    fn impl_datum(&self, impl_id: chalk_ir::ImplId) -> Arc<ImplDatum<ChalkIr>> {
+        self.db.impl_datum(self.krate, impl_id)
+    }
+    fn impls_for_trait(
+        &self,
+        trait_id: chalk_ir::TraitId,
+        parameters: &[Parameter<ChalkIr>],
+    ) -> Vec<chalk_ir::ImplId> {
+        debug!("impls_for_trait {:?}", trait_id);
+        if trait_id == UNKNOWN_TRAIT {
+            return Vec::new();
+        }
+        let trait_: TraitId = from_chalk(self.db, trait_id);
+        let mut result: Vec<_> = self
+            .db
+            .impls_for_trait(self.krate, trait_.into())
+            .iter()
+            .copied()
+            .map(|it| Impl::ImplBlock(it.into()))
+            .map(|impl_| impl_.to_chalk(self.db))
+            .collect();
+
+        let ty: Ty = from_chalk(self.db, parameters[0].assert_ty_ref().clone());
+        if let Ty::Apply(ApplicationTy { ctor: TypeCtor::Closure { def, expr }, .. }) = ty {
+            for &fn_trait in
+                [super::FnTrait::FnOnce, super::FnTrait::FnMut, super::FnTrait::Fn].iter()
+            {
+                if let Some(actual_trait) = get_fn_trait(self.db, self.krate, fn_trait) {
+                    if trait_ == actual_trait {
+                        let impl_ = super::ClosureFnTraitImplData { def, expr, fn_trait };
+                        result.push(Impl::ClosureFnTraitImpl(impl_).to_chalk(self.db));
+                    }
+                }
+            }
+        }
+
+        debug!("impls_for_trait returned {} impls", result.len());
+        result
+    }
+    fn impl_provided_for(
+        &self,
+        auto_trait_id: chalk_ir::TraitId,
+        struct_id: chalk_ir::StructId,
+    ) -> bool {
+        debug!("impl_provided_for {:?}, {:?}", auto_trait_id, struct_id);
+        false // FIXME
+    }
+    fn type_name(&self, _id: TypeKindId) -> Identifier {
+        unimplemented!()
+    }
+    fn associated_ty_value(
+        &self,
+        id: chalk_rust_ir::AssociatedTyValueId,
+    ) -> Arc<AssociatedTyValue<ChalkIr>> {
+        self.db.associated_ty_value(self.krate.into(), id)
+    }
+    fn custom_clauses(&self) -> Vec<chalk_ir::ProgramClause<ChalkIr>> {
+        vec![]
+    }
+    fn local_impls_to_coherence_check(
+        &self,
+        _trait_id: chalk_ir::TraitId,
+    ) -> Vec<chalk_ir::ImplId> {
+        // We don't do coherence checking (yet)
+        unimplemented!()
+    }
+}
+
+pub(crate) fn associated_ty_data_query(
+    db: &impl HirDatabase,
+    id: TypeId,
+) -> Arc<AssociatedTyDatum<ChalkIr>> {
+    debug!("associated_ty_data {:?}", id);
+    let type_alias: TypeAliasId = from_chalk(db, id);
+    let trait_ = match type_alias.lookup(db).container {
+        ContainerId::TraitId(t) => t,
+        _ => panic!("associated type not in trait"),
+    };
+    let generic_params = db.generic_params(type_alias.into());
+    let bound_data = chalk_rust_ir::AssociatedTyDatumBound {
+        // FIXME add bounds and where clauses
+        bounds: vec![],
+        where_clauses: vec![],
+    };
+    let datum = AssociatedTyDatum {
+        trait_id: trait_.to_chalk(db),
+        id,
+        name: lalrpop_intern::intern(&db.type_alias_data(type_alias).name.to_string()),
+        binders: make_binders(bound_data, generic_params.count_params_including_parent()),
+    };
+    Arc::new(datum)
+}
+
+pub(crate) fn trait_datum_query(
+    db: &impl HirDatabase,
+    krate: CrateId,
+    trait_id: chalk_ir::TraitId,
+) -> Arc<TraitDatum<ChalkIr>> {
+    debug!("trait_datum {:?}", trait_id);
+    if trait_id == UNKNOWN_TRAIT {
+        let trait_datum_bound = chalk_rust_ir::TraitDatumBound { where_clauses: Vec::new() };
+
+        let flags = chalk_rust_ir::TraitFlags {
+            auto: false,
+            marker: false,
+            upstream: true,
+            fundamental: false,
+            non_enumerable: true,
+            coinductive: false,
+        };
+        return Arc::new(TraitDatum {
+            id: trait_id,
+            binders: make_binders(trait_datum_bound, 1),
+            flags,
+            associated_ty_ids: vec![],
+        });
+    }
+    let trait_: TraitId = from_chalk(db, trait_id);
+    let trait_data = db.trait_data(trait_);
+    debug!("trait {:?} = {:?}", trait_id, trait_data.name);
+    let generic_params = db.generic_params(trait_.into());
+    let bound_vars = Substs::bound_vars(&generic_params);
+    let flags = chalk_rust_ir::TraitFlags {
+        auto: trait_data.auto,
+        upstream: trait_.module(db).krate != krate,
+        non_enumerable: true,
+        coinductive: false, // only relevant for Chalk testing
+        // FIXME set these flags correctly
+        marker: false,
+        fundamental: false,
+    };
+    let where_clauses = convert_where_clauses(db, trait_.into(), &bound_vars);
+    let associated_ty_ids =
+        trait_data.associated_types().map(|type_alias| type_alias.to_chalk(db)).collect();
+    let trait_datum_bound = chalk_rust_ir::TraitDatumBound { where_clauses };
+    let trait_datum = TraitDatum {
+        id: trait_id,
+        binders: make_binders(trait_datum_bound, bound_vars.len()),
+        flags,
+        associated_ty_ids,
+    };
+    Arc::new(trait_datum)
+}
+
+pub(crate) fn struct_datum_query(
+    db: &impl HirDatabase,
+    krate: CrateId,
+    struct_id: chalk_ir::StructId,
+) -> Arc<StructDatum<ChalkIr>> {
+    debug!("struct_datum {:?}", struct_id);
+    let type_ctor: TypeCtor = from_chalk(db, struct_id);
+    debug!("struct {:?} = {:?}", struct_id, type_ctor);
+    let num_params = type_ctor.num_ty_params(db);
+    let upstream = type_ctor.krate(db) != Some(krate);
+    let where_clauses = type_ctor
+        .as_generic_def()
+        .map(|generic_def| {
+            let generic_params = db.generic_params(generic_def.into());
+            let bound_vars = Substs::bound_vars(&generic_params);
+            convert_where_clauses(db, generic_def, &bound_vars)
+        })
+        .unwrap_or_else(Vec::new);
+    let flags = chalk_rust_ir::StructFlags {
+        upstream,
+        // FIXME set fundamental flag correctly
+        fundamental: false,
+    };
+    let struct_datum_bound = chalk_rust_ir::StructDatumBound {
+        fields: Vec::new(), // FIXME add fields (only relevant for auto traits)
+        where_clauses,
+    };
+    let struct_datum =
+        StructDatum { id: struct_id, binders: make_binders(struct_datum_bound, num_params), flags };
+    Arc::new(struct_datum)
+}
+
+pub(crate) fn impl_datum_query(
+    db: &impl HirDatabase,
+    krate: CrateId,
+    impl_id: chalk_ir::ImplId,
+) -> Arc<ImplDatum<ChalkIr>> {
+    let _p = ra_prof::profile("impl_datum");
+    debug!("impl_datum {:?}", impl_id);
+    let impl_: Impl = from_chalk(db, impl_id);
+    match impl_ {
+        Impl::ImplBlock(impl_block) => impl_block_datum(db, krate, impl_id, impl_block),
+        Impl::ClosureFnTraitImpl(data) => closure_fn_trait_impl_datum(db, krate, data),
+    }
+    .unwrap_or_else(invalid_impl_datum)
+}
+
+fn impl_block_datum(
+    db: &impl HirDatabase,
+    krate: CrateId,
+    chalk_id: chalk_ir::ImplId,
+    impl_id: ImplId,
+) -> Option<Arc<ImplDatum<ChalkIr>>> {
+    let trait_ref = match db.impl_ty(impl_id) {
+        ImplTy::TraitRef(it) => it,
+        ImplTy::Inherent(_) => return None,
+    };
+    let impl_data = db.impl_data(impl_id);
+
+    let generic_params = db.generic_params(impl_id.into());
+    let bound_vars = Substs::bound_vars(&generic_params);
+    let trait_ref = trait_ref.subst(&bound_vars);
+    let trait_ = trait_ref.trait_;
+    let impl_type = if impl_id.module(db).krate == krate {
+        chalk_rust_ir::ImplType::Local
+    } else {
+        chalk_rust_ir::ImplType::External
+    };
+    let where_clauses = convert_where_clauses(db, impl_id.into(), &bound_vars);
+    let negative = impl_data.is_negative;
+    debug!(
+        "impl {:?}: {}{} where {:?}",
+        chalk_id,
+        if negative { "!" } else { "" },
+        trait_ref.display(db),
+        where_clauses
+    );
+    let trait_ref = trait_ref.to_chalk(db);
+
+    let polarity = if negative {
+        chalk_rust_ir::Polarity::Negative
+    } else {
+        chalk_rust_ir::Polarity::Positive
+    };
+
+    let impl_datum_bound = chalk_rust_ir::ImplDatumBound { trait_ref, where_clauses };
+    let trait_data = db.trait_data(trait_);
+    let associated_ty_value_ids = impl_data
+        .items
+        .iter()
+        .filter_map(|item| match item {
+            AssocItemId::TypeAliasId(type_alias) => Some(*type_alias),
+            _ => None,
+        })
+        .filter(|&type_alias| {
+            // don't include associated types that don't exist in the trait
+            let name = &db.type_alias_data(type_alias).name;
+            trait_data.associated_type_by_name(name).is_some()
+        })
+        .map(|type_alias| AssocTyValue::TypeAlias(type_alias).to_chalk(db))
+        .collect();
+    debug!("impl_datum: {:?}", impl_datum_bound);
+    let impl_datum = ImplDatum {
+        binders: make_binders(impl_datum_bound, bound_vars.len()),
+        impl_type,
+        polarity,
+        associated_ty_value_ids,
+    };
+    Some(Arc::new(impl_datum))
+}
+
+fn invalid_impl_datum() -> Arc<ImplDatum<ChalkIr>> {
+    let trait_ref = chalk_ir::TraitRef {
+        trait_id: UNKNOWN_TRAIT,
+        parameters: vec![chalk_ir::TyData::BoundVar(0).cast().intern().cast()],
+    };
+    let impl_datum_bound = chalk_rust_ir::ImplDatumBound { trait_ref, where_clauses: Vec::new() };
+    let impl_datum = ImplDatum {
+        binders: make_binders(impl_datum_bound, 1),
+        impl_type: chalk_rust_ir::ImplType::External,
+        polarity: chalk_rust_ir::Polarity::Positive,
+        associated_ty_value_ids: Vec::new(),
+    };
+    Arc::new(impl_datum)
+}
+
+fn closure_fn_trait_impl_datum(
+    db: &impl HirDatabase,
+    krate: CrateId,
+    data: super::ClosureFnTraitImplData,
+) -> Option<Arc<ImplDatum<ChalkIr>>> {
+    // for some closure |X, Y| -> Z:
+    // impl<T, U, V> Fn<(T, U)> for closure<fn(T, U) -> V> { Output = V }
+
+    let trait_ = get_fn_trait(db, krate, data.fn_trait)?; // get corresponding fn trait
+
+    // validate FnOnce trait, since we need it in the assoc ty value definition
+    // and don't want to return a valid value only to find out later that FnOnce
+    // is broken
+    let fn_once_trait = get_fn_trait(db, krate, super::FnTrait::FnOnce)?;
+    let _output = db.trait_data(fn_once_trait).associated_type_by_name(&name::OUTPUT_TYPE)?;
+
+    let num_args: u16 = match &db.body(data.def.into())[data.expr] {
+        Expr::Lambda { args, .. } => args.len() as u16,
+        _ => {
+            log::warn!("closure for closure type {:?} not found", data);
+            0
+        }
+    };
+
+    let arg_ty = Ty::apply(
+        TypeCtor::Tuple { cardinality: num_args },
+        Substs::builder(num_args as usize).fill_with_bound_vars(0).build(),
+    );
+    let sig_ty = Ty::apply(
+        TypeCtor::FnPtr { num_args },
+        Substs::builder(num_args as usize + 1).fill_with_bound_vars(0).build(),
+    );
+
+    let self_ty = Ty::apply_one(TypeCtor::Closure { def: data.def, expr: data.expr }, sig_ty);
+
+    let trait_ref = TraitRef {
+        trait_: trait_.into(),
+        substs: Substs::build_for_def(db, trait_).push(self_ty).push(arg_ty).build(),
+    };
+
+    let output_ty_id = AssocTyValue::ClosureFnTraitImplOutput(data.clone()).to_chalk(db);
+
+    let impl_type = chalk_rust_ir::ImplType::External;
+
+    let impl_datum_bound = chalk_rust_ir::ImplDatumBound {
+        trait_ref: trait_ref.to_chalk(db),
+        where_clauses: Vec::new(),
+    };
+    let impl_datum = ImplDatum {
+        binders: make_binders(impl_datum_bound, num_args as usize + 1),
+        impl_type,
+        polarity: chalk_rust_ir::Polarity::Positive,
+        associated_ty_value_ids: vec![output_ty_id],
+    };
+    Some(Arc::new(impl_datum))
+}
+
+pub(crate) fn associated_ty_value_query(
+    db: &impl HirDatabase,
+    krate: CrateId,
+    id: chalk_rust_ir::AssociatedTyValueId,
+) -> Arc<chalk_rust_ir::AssociatedTyValue<ChalkIr>> {
+    let data: AssocTyValue = from_chalk(db, id);
+    match data {
+        AssocTyValue::TypeAlias(type_alias) => {
+            type_alias_associated_ty_value(db, krate, type_alias)
+        }
+        AssocTyValue::ClosureFnTraitImplOutput(data) => {
+            closure_fn_trait_output_assoc_ty_value(db, krate, data)
+        }
+    }
+}
+
+fn type_alias_associated_ty_value(
+    db: &impl HirDatabase,
+    _krate: CrateId,
+    type_alias: TypeAliasId,
+) -> Arc<AssociatedTyValue<ChalkIr>> {
+    let type_alias_data = db.type_alias_data(type_alias);
+    let impl_id = match type_alias.lookup(db).container {
+        ContainerId::ImplId(it) => it,
+        _ => panic!("assoc ty value should be in impl"),
+    };
+
+    let trait_ref = match db.impl_ty(impl_id) {
+        ImplTy::TraitRef(it) => it,
+        // we don't return any assoc ty values if the impl'd trait can't be resolved
+        ImplTy::Inherent(_) => panic!("assoc ty value should not exist"),
+    };
+
+    let assoc_ty = db
+        .trait_data(trait_ref.trait_)
+        .associated_type_by_name(&type_alias_data.name)
+        .expect("assoc ty value should not exist"); // validated when building the impl data as well
+    let generic_params = db.generic_params(impl_id.into());
+    let bound_vars = Substs::bound_vars(&generic_params);
+    let ty = db.ty(type_alias.into()).subst(&bound_vars);
+    let value_bound = chalk_rust_ir::AssociatedTyValueBound { ty: ty.to_chalk(db) };
+    let value = chalk_rust_ir::AssociatedTyValue {
+        impl_id: Impl::ImplBlock(impl_id.into()).to_chalk(db),
+        associated_ty_id: assoc_ty.to_chalk(db),
+        value: make_binders(value_bound, bound_vars.len()),
+    };
+    Arc::new(value)
+}
+
+fn closure_fn_trait_output_assoc_ty_value(
+    db: &impl HirDatabase,
+    krate: CrateId,
+    data: super::ClosureFnTraitImplData,
+) -> Arc<AssociatedTyValue<ChalkIr>> {
+    let impl_id = Impl::ClosureFnTraitImpl(data.clone()).to_chalk(db);
+
+    let num_args: u16 = match &db.body(data.def.into())[data.expr] {
+        Expr::Lambda { args, .. } => args.len() as u16,
+        _ => {
+            log::warn!("closure for closure type {:?} not found", data);
+            0
+        }
+    };
+
+    let output_ty = Ty::Bound(num_args.into());
+
+    let fn_once_trait =
+        get_fn_trait(db, krate, super::FnTrait::FnOnce).expect("assoc ty value should not exist");
+
+    let output_ty_id = db
+        .trait_data(fn_once_trait)
+        .associated_type_by_name(&name::OUTPUT_TYPE)
+        .expect("assoc ty value should not exist");
+
+    let value_bound = chalk_rust_ir::AssociatedTyValueBound { ty: output_ty.to_chalk(db) };
+
+    let value = chalk_rust_ir::AssociatedTyValue {
+        associated_ty_id: output_ty_id.to_chalk(db),
+        impl_id,
+        value: make_binders(value_bound, num_args as usize + 1),
+    };
+    Arc::new(value)
+}
+
+fn get_fn_trait(
+    db: &impl HirDatabase,
+    krate: CrateId,
+    fn_trait: super::FnTrait,
+) -> Option<TraitId> {
+    let target = db.lang_item(krate, fn_trait.lang_item_name().into())?;
+    match target {
+        LangItemTarget::TraitId(t) => Some(t),
+        _ => None,
+    }
+}
+
+fn id_from_chalk<T: InternKey>(chalk_id: chalk_ir::RawId) -> T {
+    T::from_intern_id(InternId::from(chalk_id.index))
+}
+fn id_to_chalk<T: InternKey>(salsa_id: T) -> chalk_ir::RawId {
+    chalk_ir::RawId { index: salsa_id.as_intern_id().as_u32() }
+}
+
+impl From<chalk_ir::StructId> for crate::TypeCtorId {
+    fn from(struct_id: chalk_ir::StructId) -> Self {
+        id_from_chalk(struct_id.0)
+    }
+}
+
+impl From<crate::TypeCtorId> for chalk_ir::StructId {
+    fn from(type_ctor_id: crate::TypeCtorId) -> Self {
+        chalk_ir::StructId(id_to_chalk(type_ctor_id))
+    }
+}
+
+impl From<chalk_ir::ImplId> for crate::traits::GlobalImplId {
+    fn from(impl_id: chalk_ir::ImplId) -> Self {
+        id_from_chalk(impl_id.0)
+    }
+}
+
+impl From<crate::traits::GlobalImplId> for chalk_ir::ImplId {
+    fn from(impl_id: crate::traits::GlobalImplId) -> Self {
+        chalk_ir::ImplId(id_to_chalk(impl_id))
+    }
+}
+
+impl From<chalk_rust_ir::AssociatedTyValueId> for crate::traits::AssocTyValueId {
+    fn from(id: chalk_rust_ir::AssociatedTyValueId) -> Self {
+        id_from_chalk(id.0)
+    }
+}
+
+impl From<crate::traits::AssocTyValueId> for chalk_rust_ir::AssociatedTyValueId {
+    fn from(assoc_ty_value_id: crate::traits::AssocTyValueId) -> Self {
+        chalk_rust_ir::AssociatedTyValueId(id_to_chalk(assoc_ty_value_id))
+    }
+}
diff --git a/crates/ra_hir_ty/src/utils.rs b/crates/ra_hir_ty/src/utils.rs
new file mode 100644
index 000000000..e4ba890ef
--- /dev/null
+++ b/crates/ra_hir_ty/src/utils.rs
@@ -0,0 +1,84 @@
+//! Helper functions for working with def, which don't need to be a separate
+//! query, but can't be computed directly from `*Data` (ie, which need a `db`).
+use std::sync::Arc;
+
+use hir_def::{
+    adt::VariantData,
+    db::DefDatabase,
+    resolver::{HasResolver, TypeNs},
+    type_ref::TypeRef,
+    TraitId, TypeAliasId, VariantId,
+};
+use hir_expand::name::{self, Name};
+
+// FIXME: this is wrong, b/c it can't express `trait T: PartialEq<()>`.
+// We should return a `TraitREf` here.
+fn direct_super_traits(db: &impl DefDatabase, trait_: TraitId) -> Vec<TraitId> {
+    let resolver = trait_.resolver(db);
+    // returning the iterator directly doesn't easily work because of
+    // lifetime problems, but since there usually shouldn't be more than a
+    // few direct traits this should be fine (we could even use some kind of
+    // SmallVec if performance is a concern)
+    db.generic_params(trait_.into())
+        .where_predicates
+        .iter()
+        .filter_map(|pred| match &pred.type_ref {
+            TypeRef::Path(p) if p.as_ident() == Some(&name::SELF_TYPE) => pred.bound.as_path(),
+            _ => None,
+        })
+        .filter_map(|path| match resolver.resolve_path_in_type_ns_fully(db, path) {
+            Some(TypeNs::TraitId(t)) => Some(t),
+            _ => None,
+        })
+        .collect()
+}
+
+/// Returns an iterator over the whole super trait hierarchy (including the
+/// trait itself).
+pub(super) fn all_super_traits(db: &impl DefDatabase, trait_: TraitId) -> Vec<TraitId> {
+    // we need to take care a bit here to avoid infinite loops in case of cycles
+    // (i.e. if we have `trait A: B; trait B: A;`)
+    let mut result = vec![trait_];
+    let mut i = 0;
+    while i < result.len() {
+        let t = result[i];
+        // yeah this is quadratic, but trait hierarchies should be flat
+        // enough that this doesn't matter
+        for tt in direct_super_traits(db, t) {
+            if !result.contains(&tt) {
+                result.push(tt);
+            }
+        }
+        i += 1;
+    }
+    result
+}
+
+pub(super) fn associated_type_by_name_including_super_traits(
+    db: &impl DefDatabase,
+    trait_: TraitId,
+    name: &Name,
+) -> Option<TypeAliasId> {
+    all_super_traits(db, trait_)
+        .into_iter()
+        .find_map(|t| db.trait_data(t).associated_type_by_name(name))
+}
+
+pub(super) fn variant_data(db: &impl DefDatabase, var: VariantId) -> Arc<VariantData> {
+    match var {
+        VariantId::StructId(it) => db.struct_data(it).variant_data.clone(),
+        VariantId::UnionId(it) => db.union_data(it).variant_data.clone(),
+        VariantId::EnumVariantId(it) => {
+            db.enum_data(it.parent).variants[it.local_id].variant_data.clone()
+        }
+    }
+}
+
+/// Helper for mutating `Arc<[T]>` (i.e. `Arc::make_mut` for Arc slices).
+/// The underlying values are cloned if there are other strong references.
+pub(crate) fn make_mut_slice<T: Clone>(a: &mut Arc<[T]>) -> &mut [T] {
+    if Arc::get_mut(a).is_none() {
+        *a = a.iter().cloned().collect();
+    }
+    Arc::get_mut(a).unwrap()
+}