29 files changed, 1459 insertions, 4185 deletions

diff --git a/crates/hir_ty/Cargo.toml b/crates/hir_ty/Cargo.toml
index 4b714c6d8..74129eb21 100644
--- a/crates/hir_ty/Cargo.toml
+++ b/crates/hir_ty/Cargo.toml
@@ -10,7 +10,7 @@ edition = "2018"
 doctest = false
 
 [dependencies]
-cov-mark = { version = "1.1", features = ["thread-local"] }
+cov-mark = "2.0.0-pre.1"
 itertools = "0.10.0"
 arrayvec = "0.7"
 smallvec = "1.2.0"
@@ -20,7 +20,7 @@ rustc-hash = "1.1.0"
 scoped-tls = "1"
 chalk-solve = { version = "0.68", default-features = false }
 chalk-ir = "0.68"
-chalk-recursive = "0.68"
+chalk-recursive = { version = "0.68", default-features = false }
 la-arena = { version = "0.2.0", path = "../../lib/arena" }
 once_cell = { version = "1.5.0" }
 
diff --git a/crates/hir_ty/src/builder.rs b/crates/hir_ty/src/builder.rs
index 893e727c2..bb9d84246 100644
--- a/crates/hir_ty/src/builder.rs
+++ b/crates/hir_ty/src/builder.rs
@@ -202,7 +202,7 @@ impl<T: HasInterner<Interner = Interner> + Fold<Interner>> TyBuilder<Binders<T>>
 
 impl TyBuilder<Binders<Ty>> {
     pub fn def_ty(db: &dyn HirDatabase, def: TyDefId) -> TyBuilder<Binders<Ty>> {
-        TyBuilder::subst_binders(db.ty(def.into()))
+        TyBuilder::subst_binders(db.ty(def))
     }
 
     pub fn impl_self_ty(db: &dyn HirDatabase, def: hir_def::ImplId) -> TyBuilder<Binders<Ty>> {
diff --git a/crates/hir_ty/src/chalk_db.rs b/crates/hir_ty/src/chalk_db.rs
index 4e042bf42..a4c09c742 100644
--- a/crates/hir_ty/src/chalk_db.rs
+++ b/crates/hir_ty/src/chalk_db.rs
@@ -10,16 +10,16 @@ use chalk_solve::rust_ir::{self, OpaqueTyDatumBound, WellKnownTrait};
 use base_db::CrateId;
 use hir_def::{
     lang_item::{lang_attr, LangItemTarget},
-    AssocContainerId, AssocItemId, GenericDefId, HasModule, Lookup, TypeAliasId,
+    AssocContainerId, AssocItemId, GenericDefId, HasModule, Lookup, ModuleId, TypeAliasId,
 };
 use hir_expand::name::name;
 
 use crate::{
     db::HirDatabase,
     display::HirDisplay,
-    from_assoc_type_id, from_chalk_trait_id, make_only_type_binders,
+    from_assoc_type_id, from_chalk_trait_id, from_foreign_def_id, make_only_type_binders,
     mapping::{from_chalk, ToChalk, TypeAliasAsValue},
-    method_resolution::{TyFingerprint, ALL_FLOAT_FPS, ALL_INT_FPS},
+    method_resolution::{TraitImpls, TyFingerprint, ALL_FLOAT_FPS, ALL_INT_FPS},
     to_assoc_type_id, to_chalk_trait_id,
     traits::ChalkContext,
     utils::generics,
@@ -105,12 +105,30 @@ impl<'a> chalk_solve::RustIrDatabase<Interner> for ChalkContext<'a> {
             _ => self_ty_fp.as_ref().map(std::slice::from_ref).unwrap_or(&[]),
         };
 
+        fn local_impls(db: &dyn HirDatabase, module: ModuleId) -> Option<Arc<TraitImpls>> {
+            db.trait_impls_in_block(module.containing_block()?)
+        }
+
         // Note: Since we're using impls_for_trait, only impls where the trait
-        // can be resolved should ever reach Chalk. Symbol’s value as variable is void: impl_datum relies on that
+        // can be resolved should ever reach Chalk. impl_datum relies on that
         // and will panic if the trait can't be resolved.
         let in_deps = self.db.trait_impls_in_deps(self.krate);
         let in_self = self.db.trait_impls_in_crate(self.krate);
-        let impl_maps = [in_deps, in_self];
+        let trait_module = trait_.module(self.db.upcast());
+        let type_module = match self_ty_fp {
+            Some(TyFingerprint::Adt(adt_id)) => Some(adt_id.module(self.db.upcast())),
+            Some(TyFingerprint::ForeignType(type_id)) => {
+                Some(from_foreign_def_id(type_id).module(self.db.upcast()))
+            }
+            Some(TyFingerprint::Dyn(trait_id)) => Some(trait_id.module(self.db.upcast())),
+            _ => None,
+        };
+        let impl_maps = [
+            Some(in_deps),
+            Some(in_self),
+            local_impls(self.db, trait_module),
+            type_module.and_then(|m| local_impls(self.db, m)),
+        ];
 
         let id_to_chalk = |id: hir_def::ImplId| id.to_chalk(self.db);
 
@@ -118,14 +136,16 @@ impl<'a> chalk_solve::RustIrDatabase<Interner> for ChalkContext<'a> {
             debug!("Unrestricted search for {:?} impls...", trait_);
             impl_maps
                 .iter()
-                .flat_map(|crate_impl_defs| crate_impl_defs.for_trait(trait_).map(id_to_chalk))
+                .filter_map(|o| o.as_ref())
+                .flat_map(|impls| impls.for_trait(trait_).map(id_to_chalk))
                 .collect()
         } else {
             impl_maps
                 .iter()
-                .flat_map(|crate_impl_defs| {
+                .filter_map(|o| o.as_ref())
+                .flat_map(|impls| {
                     fps.iter().flat_map(move |fp| {
-                        crate_impl_defs.for_trait_and_self_ty(trait_, *fp).map(id_to_chalk)
+                        impls.for_trait_and_self_ty(trait_, *fp).map(id_to_chalk)
                     })
                 })
                 .collect()
@@ -430,8 +450,7 @@ pub(crate) fn trait_datum_query(
         fundamental: false,
     };
     let where_clauses = convert_where_clauses(db, trait_.into(), &bound_vars);
-    let associated_ty_ids =
-        trait_data.associated_types().map(|type_alias| to_assoc_type_id(type_alias)).collect();
+    let associated_ty_ids = trait_data.associated_types().map(to_assoc_type_id).collect();
     let trait_datum_bound = rust_ir::TraitDatumBound { where_clauses };
     let well_known =
         lang_attr(db.upcast(), trait_).and_then(|name| well_known_trait_from_lang_attr(&name));
diff --git a/crates/hir_ty/src/consteval.rs b/crates/hir_ty/src/consteval.rs
index e3ceb3d62..6f0bf8f8c 100644
--- a/crates/hir_ty/src/consteval.rs
+++ b/crates/hir_ty/src/consteval.rs
@@ -49,7 +49,7 @@ pub fn usize_const(value: Option<u64>) -> Const {
     ConstData {
         ty: TyKind::Scalar(chalk_ir::Scalar::Uint(chalk_ir::UintTy::Usize)).intern(&Interner),
         value: ConstValue::Concrete(chalk_ir::ConcreteConst {
-            interned: value.map(|value| ConstScalar::Usize(value)).unwrap_or(ConstScalar::Unknown),
+            interned: value.map(ConstScalar::Usize).unwrap_or(ConstScalar::Unknown),
         }),
     }
     .intern(&Interner)
diff --git a/crates/hir_ty/src/db.rs b/crates/hir_ty/src/db.rs
index be5b9110e..b9003c413 100644
--- a/crates/hir_ty/src/db.rs
+++ b/crates/hir_ty/src/db.rs
@@ -5,8 +5,8 @@ use std::sync::Arc;
 
 use base_db::{impl_intern_key, salsa, CrateId, Upcast};
 use hir_def::{
-    db::DefDatabase, expr::ExprId, ConstParamId, DefWithBodyId, FunctionId, GenericDefId, ImplId,
-    LifetimeParamId, LocalFieldId, TypeParamId, VariantId,
+    db::DefDatabase, expr::ExprId, BlockId, ConstParamId, DefWithBodyId, FunctionId, GenericDefId,
+    ImplId, LifetimeParamId, LocalFieldId, TypeParamId, VariantId,
 };
 use la_arena::ArenaMap;
 
@@ -79,6 +79,9 @@ pub trait HirDatabase: DefDatabase + Upcast<dyn DefDatabase> {
     #[salsa::invoke(TraitImpls::trait_impls_in_crate_query)]
     fn trait_impls_in_crate(&self, krate: CrateId) -> Arc<TraitImpls>;
 
+    #[salsa::invoke(TraitImpls::trait_impls_in_block_query)]
+    fn trait_impls_in_block(&self, krate: BlockId) -> Option<Arc<TraitImpls>>;
+
     #[salsa::invoke(TraitImpls::trait_impls_in_deps_query)]
     fn trait_impls_in_deps(&self, krate: CrateId) -> Arc<TraitImpls>;
 
diff --git a/crates/hir_ty/src/diagnostics.rs b/crates/hir_ty/src/diagnostics.rs
index 283894704..6339c9687 100644
--- a/crates/hir_ty/src/diagnostics.rs
+++ b/crates/hir_ty/src/diagnostics.rs
@@ -4,325 +4,31 @@ mod match_check;
 mod unsafe_check;
 mod decl_check;
 
-use std::{any::Any, fmt};
+use std::fmt;
 
 use base_db::CrateId;
-use hir_def::{DefWithBodyId, ModuleDefId};
-use hir_expand::{name::Name, HirFileId, InFile};
-use stdx::format_to;
-use syntax::{ast, AstPtr, SyntaxNodePtr};
+use hir_def::ModuleDefId;
+use hir_expand::HirFileId;
+use syntax::{ast, AstPtr};
 
-use crate::{
-    db::HirDatabase,
-    diagnostics_sink::{Diagnostic, DiagnosticCode, DiagnosticSink},
-};
+use crate::db::HirDatabase;
 
-pub use crate::diagnostics::expr::{record_literal_missing_fields, record_pattern_missing_fields};
+pub use crate::diagnostics::{
+    expr::{
+        record_literal_missing_fields, record_pattern_missing_fields, BodyValidationDiagnostic,
+    },
+    unsafe_check::missing_unsafe,
+};
 
 pub fn validate_module_item(
     db: &dyn HirDatabase,
     krate: CrateId,
     owner: ModuleDefId,
-    sink: &mut DiagnosticSink<'_>,
-) {
+) -> Vec<IncorrectCase> {
     let _p = profile::span("validate_module_item");
-    let mut validator = decl_check::DeclValidator::new(db, krate, sink);
+    let mut validator = decl_check::DeclValidator::new(db, krate);
     validator.validate_item(owner);
-}
-
-pub fn validate_body(db: &dyn HirDatabase, owner: DefWithBodyId, sink: &mut DiagnosticSink<'_>) {
-    let _p = profile::span("validate_body");
-    let infer = db.infer(owner);
-    infer.add_diagnostics(db, owner, sink);
-    let mut validator = expr::ExprValidator::new(owner, infer.clone(), sink);
-    validator.validate_body(db);
-    let mut validator = unsafe_check::UnsafeValidator::new(owner, infer, sink);
-    validator.validate_body(db);
-}
-
-// Diagnostic: no-such-field
-//
-// This diagnostic is triggered if created structure does not have field provided in record.
-#[derive(Debug)]
-pub struct NoSuchField {
-    pub file: HirFileId,
-    pub field: AstPtr<ast::RecordExprField>,
-}
-
-impl Diagnostic for NoSuchField {
-    fn code(&self) -> DiagnosticCode {
-        DiagnosticCode("no-such-field")
-    }
-
-    fn message(&self) -> String {
-        "no such field".to_string()
-    }
-
-    fn display_source(&self) -> InFile<SyntaxNodePtr> {
-        InFile::new(self.file, self.field.clone().into())
-    }
-
-    fn as_any(&self) -> &(dyn Any + Send + 'static) {
-        self
-    }
-}
-
-// Diagnostic: missing-structure-fields
-//
-// This diagnostic is triggered if record lacks some fields that exist in the corresponding structure.
-//
-// Example:
-//
-// ```rust
-// struct A { a: u8, b: u8 }
-//
-// let a = A { a: 10 };
-// ```
-#[derive(Debug)]
-pub struct MissingFields {
-    pub file: HirFileId,
-    pub field_list_parent: AstPtr<ast::RecordExpr>,
-    pub field_list_parent_path: Option<AstPtr<ast::Path>>,
-    pub missed_fields: Vec<Name>,
-}
-
-impl Diagnostic for MissingFields {
-    fn code(&self) -> DiagnosticCode {
-        DiagnosticCode("missing-structure-fields")
-    }
-    fn message(&self) -> String {
-        let mut buf = String::from("Missing structure fields:\n");
-        for field in &self.missed_fields {
-            format_to!(buf, "- {}\n", field);
-        }
-        buf
-    }
-
-    fn display_source(&self) -> InFile<SyntaxNodePtr> {
-        InFile {
-            file_id: self.file,
-            value: self
-                .field_list_parent_path
-                .clone()
-                .map(SyntaxNodePtr::from)
-                .unwrap_or_else(|| self.field_list_parent.clone().into()),
-        }
-    }
-
-    fn as_any(&self) -> &(dyn Any + Send + 'static) {
-        self
-    }
-}
-
-// Diagnostic: missing-pat-fields
-//
-// This diagnostic is triggered if pattern lacks some fields that exist in the corresponding structure.
-//
-// Example:
-//
-// ```rust
-// struct A { a: u8, b: u8 }
-//
-// let a = A { a: 10, b: 20 };
-//
-// if let A { a } = a {
-//     // ...
-// }
-// ```
-#[derive(Debug)]
-pub struct MissingPatFields {
-    pub file: HirFileId,
-    pub field_list_parent: AstPtr<ast::RecordPat>,
-    pub field_list_parent_path: Option<AstPtr<ast::Path>>,
-    pub missed_fields: Vec<Name>,
-}
-
-impl Diagnostic for MissingPatFields {
-    fn code(&self) -> DiagnosticCode {
-        DiagnosticCode("missing-pat-fields")
-    }
-    fn message(&self) -> String {
-        let mut buf = String::from("Missing structure fields:\n");
-        for field in &self.missed_fields {
-            format_to!(buf, "- {}\n", field);
-        }
-        buf
-    }
-    fn display_source(&self) -> InFile<SyntaxNodePtr> {
-        InFile {
-            file_id: self.file,
-            value: self
-                .field_list_parent_path
-                .clone()
-                .map(SyntaxNodePtr::from)
-                .unwrap_or_else(|| self.field_list_parent.clone().into()),
-        }
-    }
-    fn as_any(&self) -> &(dyn Any + Send + 'static) {
-        self
-    }
-}
-
-// Diagnostic: missing-match-arm
-//
-// This diagnostic is triggered if `match` block is missing one or more match arms.
-#[derive(Debug)]
-pub struct MissingMatchArms {
-    pub file: HirFileId,
-    pub match_expr: AstPtr<ast::Expr>,
-    pub arms: AstPtr<ast::MatchArmList>,
-}
-
-impl Diagnostic for MissingMatchArms {
-    fn code(&self) -> DiagnosticCode {
-        DiagnosticCode("missing-match-arm")
-    }
-    fn message(&self) -> String {
-        String::from("Missing match arm")
-    }
-    fn display_source(&self) -> InFile<SyntaxNodePtr> {
-        InFile { file_id: self.file, value: self.match_expr.clone().into() }
-    }
-    fn as_any(&self) -> &(dyn Any + Send + 'static) {
-        self
-    }
-}
-
-// Diagnostic: missing-ok-or-some-in-tail-expr
-//
-// This diagnostic is triggered if a block that should return `Result` returns a value not wrapped in `Ok`,
-// or if a block that should return `Option` returns a value not wrapped in `Some`.
-//
-// Example:
-//
-// ```rust
-// fn foo() -> Result<u8, ()> {
-//     10
-// }
-// ```
-#[derive(Debug)]
-pub struct MissingOkOrSomeInTailExpr {
-    pub file: HirFileId,
-    pub expr: AstPtr<ast::Expr>,
-    // `Some` or `Ok` depending on whether the return type is Result or Option
-    pub required: String,
-}
-
-impl Diagnostic for MissingOkOrSomeInTailExpr {
-    fn code(&self) -> DiagnosticCode {
-        DiagnosticCode("missing-ok-or-some-in-tail-expr")
-    }
-    fn message(&self) -> String {
-        format!("wrap return expression in {}", self.required)
-    }
-    fn display_source(&self) -> InFile<SyntaxNodePtr> {
-        InFile { file_id: self.file, value: self.expr.clone().into() }
-    }
-    fn as_any(&self) -> &(dyn Any + Send + 'static) {
-        self
-    }
-}
-
-#[derive(Debug)]
-pub struct RemoveThisSemicolon {
-    pub file: HirFileId,
-    pub expr: AstPtr<ast::Expr>,
-}
-
-impl Diagnostic for RemoveThisSemicolon {
-    fn code(&self) -> DiagnosticCode {
-        DiagnosticCode("remove-this-semicolon")
-    }
-
-    fn message(&self) -> String {
-        "Remove this semicolon".to_string()
-    }
-
-    fn display_source(&self) -> InFile<SyntaxNodePtr> {
-        InFile { file_id: self.file, value: self.expr.clone().into() }
-    }
-
-    fn as_any(&self) -> &(dyn Any + Send + 'static) {
-        self
-    }
-}
-
-// Diagnostic: break-outside-of-loop
-//
-// This diagnostic is triggered if the `break` keyword is used outside of a loop.
-#[derive(Debug)]
-pub struct BreakOutsideOfLoop {
-    pub file: HirFileId,
-    pub expr: AstPtr<ast::Expr>,
-}
-
-impl Diagnostic for BreakOutsideOfLoop {
-    fn code(&self) -> DiagnosticCode {
-        DiagnosticCode("break-outside-of-loop")
-    }
-    fn message(&self) -> String {
-        "break outside of loop".to_string()
-    }
-    fn display_source(&self) -> InFile<SyntaxNodePtr> {
-        InFile { file_id: self.file, value: self.expr.clone().into() }
-    }
-    fn as_any(&self) -> &(dyn Any + Send + 'static) {
-        self
-    }
-}
-
-// Diagnostic: missing-unsafe
-//
-// This diagnostic is triggered if an operation marked as `unsafe` is used outside of an `unsafe` function or block.
-#[derive(Debug)]
-pub struct MissingUnsafe {
-    pub file: HirFileId,
-    pub expr: AstPtr<ast::Expr>,
-}
-
-impl Diagnostic for MissingUnsafe {
-    fn code(&self) -> DiagnosticCode {
-        DiagnosticCode("missing-unsafe")
-    }
-    fn message(&self) -> String {
-        format!("This operation is unsafe and requires an unsafe function or block")
-    }
-    fn display_source(&self) -> InFile<SyntaxNodePtr> {
-        InFile { file_id: self.file, value: self.expr.clone().into() }
-    }
-    fn as_any(&self) -> &(dyn Any + Send + 'static) {
-        self
-    }
-}
-
-// Diagnostic: mismatched-arg-count
-//
-// This diagnostic is triggered if a function is invoked with an incorrect amount of arguments.
-#[derive(Debug)]
-pub struct MismatchedArgCount {
-    pub file: HirFileId,
-    pub call_expr: AstPtr<ast::Expr>,
-    pub expected: usize,
-    pub found: usize,
-}
-
-impl Diagnostic for MismatchedArgCount {
-    fn code(&self) -> DiagnosticCode {
-        DiagnosticCode("mismatched-arg-count")
-    }
-    fn message(&self) -> String {
-        let s = if self.expected == 1 { "" } else { "s" };
-        format!("Expected {} argument{}, found {}", self.expected, s, self.found)
-    }
-    fn display_source(&self) -> InFile<SyntaxNodePtr> {
-        InFile { file_id: self.file, value: self.call_expr.clone().into() }
-    }
-    fn as_any(&self) -> &(dyn Any + Send + 'static) {
-        self
-    }
-    fn is_experimental(&self) -> bool {
-        true
-    }
+    validator.sink
 }
 
 #[derive(Debug)]
@@ -378,9 +84,6 @@ impl fmt::Display for IdentType {
     }
 }
 
-// Diagnostic: incorrect-ident-case
-//
-// This diagnostic is triggered if an item name doesn't follow https://doc.rust-lang.org/1.0.0/style/style/naming/README.html[Rust naming convention].
 #[derive(Debug)]
 pub struct IncorrectCase {
     pub file: HirFileId,
@@ -390,450 +93,3 @@ pub struct IncorrectCase {
     pub ident_text: String,
     pub suggested_text: String,
 }
-
-impl Diagnostic for IncorrectCase {
-    fn code(&self) -> DiagnosticCode {
-        DiagnosticCode("incorrect-ident-case")
-    }
-
-    fn message(&self) -> String {
-        format!(
-            "{} `{}` should have {} name, e.g. `{}`",
-            self.ident_type,
-            self.ident_text,
-            self.expected_case.to_string(),
-            self.suggested_text
-        )
-    }
-
-    fn display_source(&self) -> InFile<SyntaxNodePtr> {
-        InFile::new(self.file, self.ident.clone().into())
-    }
-
-    fn as_any(&self) -> &(dyn Any + Send + 'static) {
-        self
-    }
-
-    fn is_experimental(&self) -> bool {
-        true
-    }
-}
-
-// Diagnostic: replace-filter-map-next-with-find-map
-//
-// This diagnostic is triggered when `.filter_map(..).next()` is used, rather than the more concise `.find_map(..)`.
-#[derive(Debug)]
-pub struct ReplaceFilterMapNextWithFindMap {
-    pub file: HirFileId,
-    /// This expression is the whole method chain up to and including `.filter_map(..).next()`.
-    pub next_expr: AstPtr<ast::Expr>,
-}
-
-impl Diagnostic for ReplaceFilterMapNextWithFindMap {
-    fn code(&self) -> DiagnosticCode {
-        DiagnosticCode("replace-filter-map-next-with-find-map")
-    }
-    fn message(&self) -> String {
-        "replace filter_map(..).next() with find_map(..)".to_string()
-    }
-    fn display_source(&self) -> InFile<SyntaxNodePtr> {
-        InFile { file_id: self.file, value: self.next_expr.clone().into() }
-    }
-    fn as_any(&self) -> &(dyn Any + Send + 'static) {
-        self
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    use base_db::{fixture::WithFixture, FileId, SourceDatabase, SourceDatabaseExt};
-    use hir_def::{db::DefDatabase, AssocItemId, ModuleDefId};
-    use hir_expand::db::AstDatabase;
-    use rustc_hash::FxHashMap;
-    use syntax::{TextRange, TextSize};
-
-    use crate::{
-        diagnostics::{validate_body, validate_module_item},
-        diagnostics_sink::{Diagnostic, DiagnosticSinkBuilder},
-        test_db::TestDB,
-    };
-
-    impl TestDB {
-        fn diagnostics<F: FnMut(&dyn Diagnostic)>(&self, mut cb: F) {
-            let crate_graph = self.crate_graph();
-            for krate in crate_graph.iter() {
-                let crate_def_map = self.crate_def_map(krate);
-
-                let mut fns = Vec::new();
-                for (module_id, _) in crate_def_map.modules() {
-                    for decl in crate_def_map[module_id].scope.declarations() {
-                        let mut sink = DiagnosticSinkBuilder::new().build(&mut cb);
-                        validate_module_item(self, krate, decl, &mut sink);
-
-                        if let ModuleDefId::FunctionId(f) = decl {
-                            fns.push(f)
-                        }
-                    }
-
-                    for impl_id in crate_def_map[module_id].scope.impls() {
-                        let impl_data = self.impl_data(impl_id);
-                        for item in impl_data.items.iter() {
-                            if let AssocItemId::FunctionId(f) = item {
-                                let mut sink = DiagnosticSinkBuilder::new().build(&mut cb);
-                                validate_module_item(
-                                    self,
-                                    krate,
-                                    ModuleDefId::FunctionId(*f),
-                                    &mut sink,
-                                );
-                                fns.push(*f)
-                            }
-                        }
-                    }
-                }
-
-                for f in fns {
-                    let mut sink = DiagnosticSinkBuilder::new().build(&mut cb);
-                    validate_body(self, f.into(), &mut sink);
-                }
-            }
-        }
-    }
-
-    pub(crate) fn check_diagnostics(ra_fixture: &str) {
-        let db = TestDB::with_files(ra_fixture);
-        let annotations = db.extract_annotations();
-
-        let mut actual: FxHashMap<FileId, Vec<(TextRange, String)>> = FxHashMap::default();
-        db.diagnostics(|d| {
-            let src = d.display_source();
-            let root = db.parse_or_expand(src.file_id).unwrap();
-            // FIXME: macros...
-            let file_id = src.file_id.original_file(&db);
-            let range = src.value.to_node(&root).text_range();
-            let message = d.message();
-            actual.entry(file_id).or_default().push((range, message));
-        });
-
-        for (file_id, diags) in actual.iter_mut() {
-            diags.sort_by_key(|it| it.0.start());
-            let text = db.file_text(*file_id);
-            // For multiline spans, place them on line start
-            for (range, content) in diags {
-                if text[*range].contains('\n') {
-                    *range = TextRange::new(range.start(), range.start() + TextSize::from(1));
-                    *content = format!("... {}", content);
-                }
-            }
-        }
-
-        assert_eq!(annotations, actual);
-    }
-
-    #[test]
-    fn no_such_field_diagnostics() {
-        check_diagnostics(
-            r#"
-struct S { foo: i32, bar: () }
-impl S {
-    fn new() -> S {
-        S {
-      //^ Missing structure fields:
-      //|    - bar
-            foo: 92,
-            baz: 62,
-          //^^^^^^^ no such field
-        }
-    }
-}
-"#,
-        );
-    }
-    #[test]
-    fn no_such_field_with_feature_flag_diagnostics() {
-        check_diagnostics(
-            r#"
-//- /lib.rs crate:foo cfg:feature=foo
-struct MyStruct {
-    my_val: usize,
-    #[cfg(feature = "foo")]
-    bar: bool,
-}
-
-impl MyStruct {
-    #[cfg(feature = "foo")]
-    pub(crate) fn new(my_val: usize, bar: bool) -> Self {
-        Self { my_val, bar }
-    }
-    #[cfg(not(feature = "foo"))]
-    pub(crate) fn new(my_val: usize, _bar: bool) -> Self {
-        Self { my_val }
-    }
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn no_such_field_enum_with_feature_flag_diagnostics() {
-        check_diagnostics(
-            r#"
-//- /lib.rs crate:foo cfg:feature=foo
-enum Foo {
-    #[cfg(not(feature = "foo"))]
-    Buz,
-    #[cfg(feature = "foo")]
-    Bar,
-    Baz
-}
-
-fn test_fn(f: Foo) {
-    match f {
-        Foo::Bar => {},
-        Foo::Baz => {},
-    }
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn no_such_field_with_feature_flag_diagnostics_on_struct_lit() {
-        check_diagnostics(
-            r#"
-//- /lib.rs crate:foo cfg:feature=foo
-struct S {
-    #[cfg(feature = "foo")]
-    foo: u32,
-    #[cfg(not(feature = "foo"))]
-    bar: u32,
-}
-
-impl S {
-    #[cfg(feature = "foo")]
-    fn new(foo: u32) -> Self {
-        Self { foo }
-    }
-    #[cfg(not(feature = "foo"))]
-    fn new(bar: u32) -> Self {
-        Self { bar }
-    }
-    fn new2(bar: u32) -> Self {
-        #[cfg(feature = "foo")]
-        { Self { foo: bar } }
-        #[cfg(not(feature = "foo"))]
-        { Self { bar } }
-    }
-    fn new2(val: u32) -> Self {
-        Self {
-            #[cfg(feature = "foo")]
-            foo: val,
-            #[cfg(not(feature = "foo"))]
-            bar: val,
-        }
-    }
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn no_such_field_with_type_macro() {
-        check_diagnostics(
-            r#"
-macro_rules! Type { () => { u32 }; }
-struct Foo { bar: Type![] }
-
-impl Foo {
-    fn new() -> Self {
-        Foo { bar: 0 }
-    }
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn missing_record_pat_field_diagnostic() {
-        check_diagnostics(
-            r#"
-struct S { foo: i32, bar: () }
-fn baz(s: S) {
-    let S { foo: _ } = s;
-      //^ Missing structure fields:
-      //| - bar
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn missing_record_pat_field_no_diagnostic_if_not_exhaustive() {
-        check_diagnostics(
-            r"
-struct S { foo: i32, bar: () }
-fn baz(s: S) -> i32 {
-    match s {
-        S { foo, .. } => foo,
-    }
-}
-",
-        )
-    }
-
-    #[test]
-    fn missing_record_pat_field_box() {
-        check_diagnostics(
-            r"
-struct S { s: Box<u32> }
-fn x(a: S) {
-    let S { box s } = a;
-}
-",
-        )
-    }
-
-    #[test]
-    fn missing_record_pat_field_ref() {
-        check_diagnostics(
-            r"
-struct S { s: u32 }
-fn x(a: S) {
-    let S { ref s } = a;
-}
-",
-        )
-    }
-
-    #[test]
-    fn import_extern_crate_clash_with_inner_item() {
-        // This is more of a resolver test, but doesn't really work with the hir_def testsuite.
-
-        check_diagnostics(
-            r#"
-//- /lib.rs crate:lib deps:jwt
-mod permissions;
-
-use permissions::jwt;
-
-fn f() {
-    fn inner() {}
-    jwt::Claims {}; // should resolve to the local one with 0 fields, and not get a diagnostic
-}
-
-//- /permissions.rs
-pub mod jwt  {
-    pub struct Claims {}
-}
-
-//- /jwt/lib.rs crate:jwt
-pub struct Claims {
-    field: u8,
-}
-        "#,
-        );
-    }
-
-    #[test]
-    fn break_outside_of_loop() {
-        check_diagnostics(
-            r#"
-fn foo() { break; }
-         //^^^^^ break outside of loop
-"#,
-        );
-    }
-
-    #[test]
-    fn missing_semicolon() {
-        check_diagnostics(
-            r#"
-                fn test() -> i32 { 123; }
-                                 //^^^ Remove this semicolon
-            "#,
-        );
-    }
-
-    // Register the required standard library types to make the tests work
-    fn add_filter_map_with_find_next_boilerplate(body: &str) -> String {
-        let prefix = r#"
-        //- /main.rs crate:main deps:core
-        use core::iter::Iterator;
-        use core::option::Option::{self, Some, None};
-        "#;
-        let suffix = r#"
-        //- /core/lib.rs crate:core
-        pub mod option {
-            pub enum Option<T> { Some(T), None }
-        }
-        pub mod iter {
-            pub trait Iterator {
-                type Item;
-                fn filter_map<B, F>(self, f: F) -> FilterMap where F: FnMut(Self::Item) -> Option<B> { FilterMap }
-                fn next(&mut self) -> Option<Self::Item>;
-            }
-            pub struct FilterMap {}
-            impl Iterator for FilterMap {
-                type Item = i32;
-                fn next(&mut self) -> i32 { 7 }
-            }
-        }
-        "#;
-        format!("{}{}{}", prefix, body, suffix)
-    }
-
-    #[test]
-    fn replace_filter_map_next_with_find_map2() {
-        check_diagnostics(&add_filter_map_with_find_next_boilerplate(
-            r#"
-            fn foo() {
-                let m = [1, 2, 3].iter().filter_map(|x| if *x == 2 { Some (4) } else { None }).next();
-                      //^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ replace filter_map(..).next() with find_map(..)
-            }
-        "#,
-        ));
-    }
-
-    #[test]
-    fn replace_filter_map_next_with_find_map_no_diagnostic_without_next() {
-        check_diagnostics(&add_filter_map_with_find_next_boilerplate(
-            r#"
-            fn foo() {
-                let m = [1, 2, 3]
-                    .iter()
-                    .filter_map(|x| if *x == 2 { Some (4) } else { None })
-                    .len();
-            }
-            "#,
-        ));
-    }
-
-    #[test]
-    fn replace_filter_map_next_with_find_map_no_diagnostic_with_intervening_methods() {
-        check_diagnostics(&add_filter_map_with_find_next_boilerplate(
-            r#"
-            fn foo() {
-                let m = [1, 2, 3]
-                    .iter()
-                    .filter_map(|x| if *x == 2 { Some (4) } else { None })
-                    .map(|x| x + 2)
-                    .len();
-            }
-            "#,
-        ));
-    }
-
-    #[test]
-    fn replace_filter_map_next_with_find_map_no_diagnostic_if_not_in_chain() {
-        check_diagnostics(&add_filter_map_with_find_next_boilerplate(
-            r#"
-            fn foo() {
-                let m = [1, 2, 3]
-                    .iter()
-                    .filter_map(|x| if *x == 2 { Some (4) } else { None });
-                let n = m.next();
-            }
-            "#,
-        ));
-    }
-}
diff --git a/crates/hir_ty/src/diagnostics/decl_check.rs b/crates/hir_ty/src/diagnostics/decl_check.rs
index cfb5d7320..f26150b77 100644
--- a/crates/hir_ty/src/diagnostics/decl_check.rs
+++ b/crates/hir_ty/src/diagnostics/decl_check.rs
@@ -29,7 +29,6 @@ use syntax::{
 use crate::{
     db::HirDatabase,
     diagnostics::{decl_check::case_conv::*, CaseType, IdentType, IncorrectCase},
-    diagnostics_sink::DiagnosticSink,
 };
 
 mod allow {
@@ -40,10 +39,10 @@ mod allow {
     pub(super) const NON_CAMEL_CASE_TYPES: &str = "non_camel_case_types";
 }
 
-pub(super) struct DeclValidator<'a, 'b> {
+pub(super) struct DeclValidator<'a> {
     db: &'a dyn HirDatabase,
     krate: CrateId,
-    sink: &'a mut DiagnosticSink<'b>,
+    pub(super) sink: Vec<IncorrectCase>,
 }
 
 #[derive(Debug)]
@@ -53,13 +52,9 @@ struct Replacement {
     expected_case: CaseType,
 }
 
-impl<'a, 'b> DeclValidator<'a, 'b> {
-    pub(super) fn new(
-        db: &'a dyn HirDatabase,
-        krate: CrateId,
-        sink: &'a mut DiagnosticSink<'b>,
-    ) -> DeclValidator<'a, 'b> {
-        DeclValidator { db, krate, sink }
+impl<'a> DeclValidator<'a> {
+    pub(super) fn new(db: &'a dyn HirDatabase, krate: CrateId) -> DeclValidator<'a> {
+        DeclValidator { db, krate, sink: Vec::new() }
     }
 
     pub(super) fn validate_item(&mut self, item: ModuleDefId) {
@@ -131,7 +126,7 @@ impl<'a, 'b> DeclValidator<'a, 'b> {
         for (_, block_def_map) in body.blocks(self.db.upcast()) {
             for (_, module) in block_def_map.modules() {
                 for def_id in module.scope.declarations() {
-                    let mut validator = DeclValidator::new(self.db, self.krate, self.sink);
+                    let mut validator = DeclValidator::new(self.db, self.krate);
                     validator.validate_item(def_id);
                 }
             }
@@ -623,343 +618,3 @@ impl<'a, 'b> DeclValidator<'a, 'b> {
         self.sink.push(diagnostic);
     }
 }
-
-#[cfg(test)]
-mod tests {
-    use crate::diagnostics::tests::check_diagnostics;
-
-    #[test]
-    fn incorrect_function_name() {
-        check_diagnostics(
-            r#"
-fn NonSnakeCaseName() {}
-// ^^^^^^^^^^^^^^^^ Function `NonSnakeCaseName` should have snake_case name, e.g. `non_snake_case_name`
-"#,
-        );
-    }
-
-    #[test]
-    fn incorrect_function_params() {
-        check_diagnostics(
-            r#"
-fn foo(SomeParam: u8) {}
-    // ^^^^^^^^^ Parameter `SomeParam` should have snake_case name, e.g. `some_param`
-
-fn foo2(ok_param: &str, CAPS_PARAM: u8) {}
-                     // ^^^^^^^^^^ Parameter `CAPS_PARAM` should have snake_case name, e.g. `caps_param`
-"#,
-        );
-    }
-
-    #[test]
-    fn incorrect_variable_names() {
-        check_diagnostics(
-            r#"
-fn foo() {
-    let SOME_VALUE = 10;
-     // ^^^^^^^^^^ Variable `SOME_VALUE` should have snake_case name, e.g. `some_value`
-    let AnotherValue = 20;
-     // ^^^^^^^^^^^^ Variable `AnotherValue` should have snake_case name, e.g. `another_value`
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn incorrect_struct_names() {
-        check_diagnostics(
-            r#"
-struct non_camel_case_name {}
-    // ^^^^^^^^^^^^^^^^^^^ Structure `non_camel_case_name` should have CamelCase name, e.g. `NonCamelCaseName`
-
-struct SCREAMING_CASE {}
-    // ^^^^^^^^^^^^^^ Structure `SCREAMING_CASE` should have CamelCase name, e.g. `ScreamingCase`
-"#,
-        );
-    }
-
-    #[test]
-    fn no_diagnostic_for_camel_cased_acronyms_in_struct_name() {
-        check_diagnostics(
-            r#"
-struct AABB {}
-"#,
-        );
-    }
-
-    #[test]
-    fn incorrect_struct_field() {
-        check_diagnostics(
-            r#"
-struct SomeStruct { SomeField: u8 }
-                 // ^^^^^^^^^ Field `SomeField` should have snake_case name, e.g. `some_field`
-"#,
-        );
-    }
-
-    #[test]
-    fn incorrect_enum_names() {
-        check_diagnostics(
-            r#"
-enum some_enum { Val(u8) }
-  // ^^^^^^^^^ Enum `some_enum` should have CamelCase name, e.g. `SomeEnum`
-
-enum SOME_ENUM
-  // ^^^^^^^^^ Enum `SOME_ENUM` should have CamelCase name, e.g. `SomeEnum`
-"#,
-        );
-    }
-
-    #[test]
-    fn no_diagnostic_for_camel_cased_acronyms_in_enum_name() {
-        check_diagnostics(
-            r#"
-enum AABB {}
-"#,
-        );
-    }
-
-    #[test]
-    fn incorrect_enum_variant_name() {
-        check_diagnostics(
-            r#"
-enum SomeEnum { SOME_VARIANT(u8) }
-             // ^^^^^^^^^^^^ Variant `SOME_VARIANT` should have CamelCase name, e.g. `SomeVariant`
-"#,
-        );
-    }
-
-    #[test]
-    fn incorrect_const_name() {
-        check_diagnostics(
-            r#"
-const some_weird_const: u8 = 10;
-   // ^^^^^^^^^^^^^^^^ Constant `some_weird_const` should have UPPER_SNAKE_CASE name, e.g. `SOME_WEIRD_CONST`
-
-fn func() {
-    const someConstInFunc: &str = "hi there";
-       // ^^^^^^^^^^^^^^^ Constant `someConstInFunc` should have UPPER_SNAKE_CASE name, e.g. `SOME_CONST_IN_FUNC`
-
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn incorrect_static_name() {
-        check_diagnostics(
-            r#"
-static some_weird_const: u8 = 10;
-    // ^^^^^^^^^^^^^^^^ Static variable `some_weird_const` should have UPPER_SNAKE_CASE name, e.g. `SOME_WEIRD_CONST`
-
-fn func() {
-    static someConstInFunc: &str = "hi there";
-        // ^^^^^^^^^^^^^^^ Static variable `someConstInFunc` should have UPPER_SNAKE_CASE name, e.g. `SOME_CONST_IN_FUNC`
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn fn_inside_impl_struct() {
-        check_diagnostics(
-            r#"
-struct someStruct;
-    // ^^^^^^^^^^ Structure `someStruct` should have CamelCase name, e.g. `SomeStruct`
-
-impl someStruct {
-    fn SomeFunc(&self) {
-    // ^^^^^^^^ Function `SomeFunc` should have snake_case name, e.g. `some_func`
-        static someConstInFunc: &str = "hi there";
-            // ^^^^^^^^^^^^^^^ Static variable `someConstInFunc` should have UPPER_SNAKE_CASE name, e.g. `SOME_CONST_IN_FUNC`
-        let WHY_VAR_IS_CAPS = 10;
-         // ^^^^^^^^^^^^^^^ Variable `WHY_VAR_IS_CAPS` should have snake_case name, e.g. `why_var_is_caps`
-    }
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn no_diagnostic_for_enum_varinats() {
-        check_diagnostics(
-            r#"
-enum Option { Some, None }
-
-fn main() {
-    match Option::None {
-        None => (),
-        Some => (),
-    }
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn non_let_bind() {
-        check_diagnostics(
-            r#"
-enum Option { Some, None }
-
-fn main() {
-    match Option::None {
-        SOME_VAR @ None => (),
-     // ^^^^^^^^ Variable `SOME_VAR` should have snake_case name, e.g. `some_var`
-        Some => (),
-    }
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn allow_attributes() {
-        check_diagnostics(
-            r#"
-#[allow(non_snake_case)]
-fn NonSnakeCaseName(SOME_VAR: u8) -> u8{
-    // cov_flags generated output from elsewhere in this file
-    extern "C" {
-        #[no_mangle]
-        static lower_case: u8;
-    }
-
-    let OtherVar = SOME_VAR + 1;
-    OtherVar
-}
-
-#[allow(nonstandard_style)]
-mod CheckNonstandardStyle {
-    fn HiImABadFnName() {}
-}
-
-#[allow(bad_style)]
-mod CheckBadStyle {
-    fn HiImABadFnName() {}
-}
-
-mod F {
-    #![allow(non_snake_case)]
-    fn CheckItWorksWithModAttr(BAD_NAME_HI: u8) {}
-}
-
-#[allow(non_snake_case, non_camel_case_types)]
-pub struct some_type {
-    SOME_FIELD: u8,
-    SomeField: u16,
-}
-
-#[allow(non_upper_case_globals)]
-pub const some_const: u8 = 10;
-
-#[allow(non_upper_case_globals)]
-pub static SomeStatic: u8 = 10;
-    "#,
-        );
-    }
-
-    #[test]
-    fn allow_attributes_crate_attr() {
-        check_diagnostics(
-            r#"
-#![allow(non_snake_case)]
-
-mod F {
-    fn CheckItWorksWithCrateAttr(BAD_NAME_HI: u8) {}
-}
-    "#,
-        );
-    }
-
-    #[test]
-    #[ignore]
-    fn bug_trait_inside_fn() {
-        // FIXME:
-        // This is broken, and in fact, should not even be looked at by this
-        // lint in the first place. There's weird stuff going on in the
-        // collection phase.
-        // It's currently being brought in by:
-        // * validate_func on `a` recursing into modules
-        // * then it finds the trait and then the function while iterating
-        //   through modules
-        // * then validate_func is called on Dirty
-        // * ... which then proceeds to look at some unknown module taking no
-        //   attrs from either the impl or the fn a, and then finally to the root
-        //   module
-        //
-        // It should find the attribute on the trait, but it *doesn't even see
-        // the trait* as far as I can tell.
-
-        check_diagnostics(
-            r#"
-trait T { fn a(); }
-struct U {}
-impl T for U {
-    fn a() {
-        // this comes out of bitflags, mostly
-        #[allow(non_snake_case)]
-        trait __BitFlags {
-            const HiImAlsoBad: u8 = 2;
-            #[inline]
-            fn Dirty(&self) -> bool {
-                false
-            }
-        }
-
-    }
-}
-    "#,
-        );
-    }
-
-    #[test]
-    #[ignore]
-    fn bug_traits_arent_checked() {
-        // FIXME: Traits and functions in traits aren't currently checked by
-        // r-a, even though rustc will complain about them.
-        check_diagnostics(
-            r#"
-trait BAD_TRAIT {
-    // ^^^^^^^^^ Trait `BAD_TRAIT` should have CamelCase name, e.g. `BadTrait`
-    fn BAD_FUNCTION();
-    // ^^^^^^^^^^^^ Function `BAD_FUNCTION` should have snake_case name, e.g. `bad_function`
-    fn BadFunction();
-    // ^^^^^^^^^^^^ Function `BadFunction` should have snake_case name, e.g. `bad_function`
-}
-    "#,
-        );
-    }
-
-    #[test]
-    fn ignores_extern_items() {
-        cov_mark::check!(extern_func_incorrect_case_ignored);
-        cov_mark::check!(extern_static_incorrect_case_ignored);
-        check_diagnostics(
-            r#"
-extern {
-    fn NonSnakeCaseName(SOME_VAR: u8) -> u8;
-    pub static SomeStatic: u8 = 10;
-}
-            "#,
-        );
-    }
-
-    #[test]
-    fn infinite_loop_inner_items() {
-        check_diagnostics(
-            r#"
-fn qualify() {
-    mod foo {
-        use super::*;
-    }
-}
-            "#,
-        )
-    }
-
-    #[test] // Issue #8809.
-    fn parenthesized_parameter() {
-        check_diagnostics(r#"fn f((O): _) {}"#)
-    }
-}
diff --git a/crates/hir_ty/src/diagnostics/expr.rs b/crates/hir_ty/src/diagnostics/expr.rs
index a2a4d61db..b809b96a0 100644
--- a/crates/hir_ty/src/diagnostics/expr.rs
+++ b/crates/hir_ty/src/diagnostics/expr.rs
@@ -8,20 +8,15 @@ use hir_def::{
     expr::Statement, path::path, resolver::HasResolver, AssocItemId, DefWithBodyId, HasModule,
 };
 use hir_expand::name;
+use itertools::Either;
 use rustc_hash::FxHashSet;
-use syntax::{ast, AstPtr};
 
 use crate::{
     db::HirDatabase,
-    diagnostics::{
-        match_check::{
-            self,
-            usefulness::{compute_match_usefulness, expand_pattern, MatchCheckCtx, PatternArena},
-        },
-        MismatchedArgCount, MissingFields, MissingMatchArms, MissingOkOrSomeInTailExpr,
-        MissingPatFields, RemoveThisSemicolon,
+    diagnostics::match_check::{
+        self,
+        usefulness::{compute_match_usefulness, expand_pattern, MatchCheckCtx, PatternArena},
     },
-    diagnostics_sink::DiagnosticSink,
     AdtId, InferenceResult, Interner, TyExt, TyKind,
 };
 
@@ -31,38 +26,67 @@ pub(crate) use hir_def::{
     LocalFieldId, VariantId,
 };
 
-use super::ReplaceFilterMapNextWithFindMap;
+pub enum BodyValidationDiagnostic {
+    RecordMissingFields {
+        record: Either<ExprId, PatId>,
+        variant: VariantId,
+        missed_fields: Vec<LocalFieldId>,
+    },
+    ReplaceFilterMapNextWithFindMap {
+        method_call_expr: ExprId,
+    },
+    MismatchedArgCount {
+        call_expr: ExprId,
+        expected: usize,
+        found: usize,
+    },
+    RemoveThisSemicolon {
+        expr: ExprId,
+    },
+    MissingOkOrSomeInTailExpr {
+        expr: ExprId,
+        required: String,
+    },
+    MissingMatchArms {
+        match_expr: ExprId,
+    },
+}
+
+impl BodyValidationDiagnostic {
+    pub fn collect(db: &dyn HirDatabase, owner: DefWithBodyId) -> Vec<BodyValidationDiagnostic> {
+        let _p = profile::span("BodyValidationDiagnostic::collect");
+        let infer = db.infer(owner);
+        let mut validator = ExprValidator::new(owner, infer.clone());
+        validator.validate_body(db);
+        validator.diagnostics
+    }
+}
 
-pub(super) struct ExprValidator<'a, 'b: 'a> {
+struct ExprValidator {
     owner: DefWithBodyId,
     infer: Arc<InferenceResult>,
-    sink: &'a mut DiagnosticSink<'b>,
+    pub(super) diagnostics: Vec<BodyValidationDiagnostic>,
 }
 
-impl<'a, 'b> ExprValidator<'a, 'b> {
-    pub(super) fn new(
-        owner: DefWithBodyId,
-        infer: Arc<InferenceResult>,
-        sink: &'a mut DiagnosticSink<'b>,
-    ) -> ExprValidator<'a, 'b> {
-        ExprValidator { owner, infer, sink }
+impl ExprValidator {
+    fn new(owner: DefWithBodyId, infer: Arc<InferenceResult>) -> ExprValidator {
+        ExprValidator { owner, infer, diagnostics: Vec::new() }
     }
 
-    pub(super) fn validate_body(&mut self, db: &dyn HirDatabase) {
+    fn validate_body(&mut self, db: &dyn HirDatabase) {
         self.check_for_filter_map_next(db);
 
         let body = db.body(self.owner);
 
         for (id, expr) in body.exprs.iter() {
-            if let Some((variant_def, missed_fields, true)) =
+            if let Some((variant, missed_fields, true)) =
                 record_literal_missing_fields(db, &self.infer, id, expr)
             {
-                self.create_record_literal_missing_fields_diagnostic(
-                    id,
-                    db,
-                    variant_def,
+                self.diagnostics.push(BodyValidationDiagnostic::RecordMissingFields {
+                    record: Either::Left(id),
+                    variant,
                     missed_fields,
-                );
+                });
             }
 
             match expr {
@@ -76,15 +100,14 @@ impl<'a, 'b> ExprValidator<'a, 'b> {
             }
         }
         for (id, pat) in body.pats.iter() {
-            if let Some((variant_def, missed_fields, true)) =
+            if let Some((variant, missed_fields, true)) =
                 record_pattern_missing_fields(db, &self.infer, id, pat)
             {
-                self.create_record_pattern_missing_fields_diagnostic(
-                    id,
-                    db,
-                    variant_def,
+                self.diagnostics.push(BodyValidationDiagnostic::RecordMissingFields {
+                    record: Either::Right(id),
+                    variant,
                     missed_fields,
-                );
+                });
             }
         }
         let body_expr = &body[body.body_expr];
@@ -92,71 +115,7 @@ impl<'a, 'b> ExprValidator<'a, 'b> {
             if let Some(t) = tail {
                 self.validate_results_in_tail_expr(body.body_expr, *t, db);
             } else if let Some(Statement::Expr { expr: id, .. }) = statements.last() {
-                self.validate_missing_tail_expr(body.body_expr, *id, db);
-            }
-        }
-    }
-
-    fn create_record_literal_missing_fields_diagnostic(
-        &mut self,
-        id: ExprId,
-        db: &dyn HirDatabase,
-        variant_def: VariantId,
-        missed_fields: Vec<LocalFieldId>,
-    ) {
-        // XXX: only look at source_map if we do have missing fields
-        let (_, source_map) = db.body_with_source_map(self.owner);
-
-        if let Ok(source_ptr) = source_map.expr_syntax(id) {
-            let root = source_ptr.file_syntax(db.upcast());
-            if let ast::Expr::RecordExpr(record_expr) = &source_ptr.value.to_node(&root) {
-                if let Some(_) = record_expr.record_expr_field_list() {
-                    let variant_data = variant_def.variant_data(db.upcast());
-                    let missed_fields = missed_fields
-                        .into_iter()
-                        .map(|idx| variant_data.fields()[idx].name.clone())
-                        .collect();
-                    self.sink.push(MissingFields {
-                        file: source_ptr.file_id,
-                        field_list_parent: AstPtr::new(&record_expr),
-                        field_list_parent_path: record_expr.path().map(|path| AstPtr::new(&path)),
-                        missed_fields,
-                    })
-                }
-            }
-        }
-    }
-
-    fn create_record_pattern_missing_fields_diagnostic(
-        &mut self,
-        id: PatId,
-        db: &dyn HirDatabase,
-        variant_def: VariantId,
-        missed_fields: Vec<LocalFieldId>,
-    ) {
-        // XXX: only look at source_map if we do have missing fields
-        let (_, source_map) = db.body_with_source_map(self.owner);
-
-        if let Ok(source_ptr) = source_map.pat_syntax(id) {
-            if let Some(expr) = source_ptr.value.as_ref().left() {
-                let root = source_ptr.file_syntax(db.upcast());
-                if let ast::Pat::RecordPat(record_pat) = expr.to_node(&root) {
-                    if let Some(_) = record_pat.record_pat_field_list() {
-                        let variant_data = variant_def.variant_data(db.upcast());
-                        let missed_fields = missed_fields
-                            .into_iter()
-                            .map(|idx| variant_data.fields()[idx].name.clone())
-                            .collect();
-                        self.sink.push(MissingPatFields {
-                            file: source_ptr.file_id,
-                            field_list_parent: AstPtr::new(&record_pat),
-                            field_list_parent_path: record_pat
-                                .path()
-                                .map(|path| AstPtr::new(&path)),
-                            missed_fields,
-                        })
-                    }
-                }
+                self.validate_missing_tail_expr(body.body_expr, *id);
             }
         }
     }
@@ -199,13 +158,11 @@ impl<'a, 'b> ExprValidator<'a, 'b> {
                 if function_id == *next_function_id {
                     if let Some(filter_map_id) = prev {
                         if *receiver == filter_map_id {
-                            let (_, source_map) = db.body_with_source_map(self.owner);
-                            if let Ok(next_source_ptr) = source_map.expr_syntax(id) {
-                                self.sink.push(ReplaceFilterMapNextWithFindMap {
-                                    file: next_source_ptr.file_id,
-                                    next_expr: next_source_ptr.value,
-                                });
-                            }
+                            self.diagnostics.push(
+                                BodyValidationDiagnostic::ReplaceFilterMapNextWithFindMap {
+                                    method_call_expr: id,
+                                },
+                            );
                         }
                     }
                 }
@@ -266,19 +223,15 @@ impl<'a, 'b> ExprValidator<'a, 'b> {
         let mut arg_count = args.len();
 
         if arg_count != param_count {
-            let (_, source_map) = db.body_with_source_map(self.owner);
-            if let Ok(source_ptr) = source_map.expr_syntax(call_id) {
-                if is_method_call {
-                    param_count -= 1;
-                    arg_count -= 1;
-                }
-                self.sink.push(MismatchedArgCount {
-                    file: source_ptr.file_id,
-                    call_expr: source_ptr.value,
-                    expected: param_count,
-                    found: arg_count,
-                });
+            if is_method_call {
+                param_count -= 1;
+                arg_count -= 1;
             }
+            self.diagnostics.push(BodyValidationDiagnostic::MismatchedArgCount {
+                call_expr: call_id,
+                expected: param_count,
+                found: arg_count,
+            });
         }
     }
 
@@ -346,8 +299,7 @@ impl<'a, 'b> ExprValidator<'a, 'b> {
             // fit the match expression, we skip this diagnostic. Skipping the entire
             // diagnostic rather than just not including this match arm is preferred
             // to avoid the chance of false positives.
-            #[cfg(test)]
-            match_check::tests::report_bail_out(db, self.owner, arm.pat, self.sink);
+            cov_mark::hit!(validate_match_bailed_out);
             return;
         }
 
@@ -382,20 +334,7 @@ impl<'a, 'b> ExprValidator<'a, 'b> {
         // FIXME Report witnesses
         // eprintln!("compute_match_usefulness(..) -> {:?}", &witnesses);
         if !witnesses.is_empty() {
-            if let Ok(source_ptr) = source_map.expr_syntax(id) {
-                let root = source_ptr.file_syntax(db.upcast());
-                if let ast::Expr::MatchExpr(match_expr) = &source_ptr.value.to_node(&root) {
-                    if let (Some(match_expr), Some(arms)) =
-                        (match_expr.expr(), match_expr.match_arm_list())
-                    {
-                        self.sink.push(MissingMatchArms {
-                            file: source_ptr.file_id,
-                            match_expr: AstPtr::new(&match_expr),
-                            arms: AstPtr::new(&arms),
-                        })
-                    }
-                }
-            }
+            self.diagnostics.push(BodyValidationDiagnostic::MissingMatchArms { match_expr: id });
         }
     }
 
@@ -453,24 +392,12 @@ impl<'a, 'b> ExprValidator<'a, 'b> {
         if params.len(&Interner) > 0
             && params.at(&Interner, 0).ty(&Interner) == Some(&mismatch.actual)
         {
-            let (_, source_map) = db.body_with_source_map(self.owner);
-
-            if let Ok(source_ptr) = source_map.expr_syntax(id) {
-                self.sink.push(MissingOkOrSomeInTailExpr {
-                    file: source_ptr.file_id,
-                    expr: source_ptr.value,
-                    required,
-                });
-            }
+            self.diagnostics
+                .push(BodyValidationDiagnostic::MissingOkOrSomeInTailExpr { expr: id, required });
         }
     }
 
-    fn validate_missing_tail_expr(
-        &mut self,
-        body_id: ExprId,
-        possible_tail_id: ExprId,
-        db: &dyn HirDatabase,
-    ) {
+    fn validate_missing_tail_expr(&mut self, body_id: ExprId, possible_tail_id: ExprId) {
         let mismatch = match self.infer.type_mismatch_for_expr(body_id) {
             Some(m) => m,
             None => return,
@@ -485,12 +412,8 @@ impl<'a, 'b> ExprValidator<'a, 'b> {
             return;
         }
 
-        let (_, source_map) = db.body_with_source_map(self.owner);
-
-        if let Ok(source_ptr) = source_map.expr_syntax(possible_tail_id) {
-            self.sink
-                .push(RemoveThisSemicolon { file: source_ptr.file_id, expr: source_ptr.value });
-        }
+        self.diagnostics
+            .push(BodyValidationDiagnostic::RemoveThisSemicolon { expr: possible_tail_id });
     }
 }
 
@@ -568,258 +491,3 @@ fn types_of_subpatterns_do_match(pat: PatId, body: &Body, infer: &InferenceResul
     walk(pat, body, infer, &mut has_type_mismatches);
     !has_type_mismatches
 }
-
-#[cfg(test)]
-mod tests {
-    use crate::diagnostics::tests::check_diagnostics;
-
-    #[test]
-    fn simple_free_fn_zero() {
-        check_diagnostics(
-            r#"
-fn zero() {}
-fn f() { zero(1); }
-       //^^^^^^^ Expected 0 arguments, found 1
-"#,
-        );
-
-        check_diagnostics(
-            r#"
-fn zero() {}
-fn f() { zero(); }
-"#,
-        );
-    }
-
-    #[test]
-    fn simple_free_fn_one() {
-        check_diagnostics(
-            r#"
-fn one(arg: u8) {}
-fn f() { one(); }
-       //^^^^^ Expected 1 argument, found 0
-"#,
-        );
-
-        check_diagnostics(
-            r#"
-fn one(arg: u8) {}
-fn f() { one(1); }
-"#,
-        );
-    }
-
-    #[test]
-    fn method_as_fn() {
-        check_diagnostics(
-            r#"
-struct S;
-impl S { fn method(&self) {} }
-
-fn f() {
-    S::method();
-} //^^^^^^^^^^^ Expected 1 argument, found 0
-"#,
-        );
-
-        check_diagnostics(
-            r#"
-struct S;
-impl S { fn method(&self) {} }
-
-fn f() {
-    S::method(&S);
-    S.method();
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn method_with_arg() {
-        check_diagnostics(
-            r#"
-struct S;
-impl S { fn method(&self, arg: u8) {} }
-
-            fn f() {
-                S.method();
-            } //^^^^^^^^^^ Expected 1 argument, found 0
-            "#,
-        );
-
-        check_diagnostics(
-            r#"
-struct S;
-impl S { fn method(&self, arg: u8) {} }
-
-fn f() {
-    S::method(&S, 0);
-    S.method(1);
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn method_unknown_receiver() {
-        // note: this is incorrect code, so there might be errors on this in the
-        // future, but we shouldn't emit an argument count diagnostic here
-        check_diagnostics(
-            r#"
-trait Foo { fn method(&self, arg: usize) {} }
-
-fn f() {
-    let x;
-    x.method();
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn tuple_struct() {
-        check_diagnostics(
-            r#"
-struct Tup(u8, u16);
-fn f() {
-    Tup(0);
-} //^^^^^^ Expected 2 arguments, found 1
-"#,
-        )
-    }
-
-    #[test]
-    fn enum_variant() {
-        check_diagnostics(
-            r#"
-enum En { Variant(u8, u16), }
-fn f() {
-    En::Variant(0);
-} //^^^^^^^^^^^^^^ Expected 2 arguments, found 1
-"#,
-        )
-    }
-
-    #[test]
-    fn enum_variant_type_macro() {
-        check_diagnostics(
-            r#"
-macro_rules! Type {
-    () => { u32 };
-}
-enum Foo {
-    Bar(Type![])
-}
-impl Foo {
-    fn new() {
-        Foo::Bar(0);
-        Foo::Bar(0, 1);
-      //^^^^^^^^^^^^^^ Expected 1 argument, found 2
-        Foo::Bar();
-      //^^^^^^^^^^ Expected 1 argument, found 0
-    }
-}
-        "#,
-        );
-    }
-
-    #[test]
-    fn varargs() {
-        check_diagnostics(
-            r#"
-extern "C" {
-    fn fixed(fixed: u8);
-    fn varargs(fixed: u8, ...);
-    fn varargs2(...);
-}
-
-fn f() {
-    unsafe {
-        fixed(0);
-        fixed(0, 1);
-      //^^^^^^^^^^^ Expected 1 argument, found 2
-        varargs(0);
-        varargs(0, 1);
-        varargs2();
-        varargs2(0);
-        varargs2(0, 1);
-    }
-}
-        "#,
-        )
-    }
-
-    #[test]
-    fn arg_count_lambda() {
-        check_diagnostics(
-            r#"
-fn main() {
-    let f = |()| ();
-    f();
-  //^^^ Expected 1 argument, found 0
-    f(());
-    f((), ());
-  //^^^^^^^^^ Expected 1 argument, found 2
-}
-"#,
-        )
-    }
-
-    #[test]
-    fn cfgd_out_call_arguments() {
-        check_diagnostics(
-            r#"
-struct C(#[cfg(FALSE)] ());
-impl C {
-    fn new() -> Self {
-        Self(
-            #[cfg(FALSE)]
-            (),
-        )
-    }
-
-    fn method(&self) {}
-}
-
-fn main() {
-    C::new().method(#[cfg(FALSE)] 0);
-}
-            "#,
-        );
-    }
-
-    #[test]
-    fn cfgd_out_fn_params() {
-        check_diagnostics(
-            r#"
-fn foo(#[cfg(NEVER)] x: ()) {}
-
-struct S;
-
-impl S {
-    fn method(#[cfg(NEVER)] self) {}
-    fn method2(#[cfg(NEVER)] self, arg: u8) {}
-    fn method3(self, #[cfg(NEVER)] arg: u8) {}
-}
-
-extern "C" {
-    fn fixed(fixed: u8, #[cfg(NEVER)] ...);
-    fn varargs(#[cfg(not(NEVER))] ...);
-}
-
-fn main() {
-    foo();
-    S::method();
-    S::method2(0);
-    S::method3(S);
-    S.method3();
-    unsafe {
-        fixed(0);
-        varargs(1, 2, 3);
-    }
-}
-            "#,
-        )
-    }
-}
diff --git a/crates/hir_ty/src/diagnostics/match_check.rs b/crates/hir_ty/src/diagnostics/match_check.rs
index c8e1b23de..a30e42699 100644
--- a/crates/hir_ty/src/diagnostics/match_check.rs
+++ b/crates/hir_ty/src/diagnostics/match_check.rs
@@ -364,960 +364,3 @@ impl PatternFoldable for PatKind {
         }
     }
 }
-
-#[cfg(test)]
-pub(super) mod tests {
-    mod report {
-        use std::any::Any;
-
-        use hir_def::{expr::PatId, DefWithBodyId};
-        use hir_expand::{HirFileId, InFile};
-        use syntax::SyntaxNodePtr;
-
-        use crate::{
-            db::HirDatabase,
-            diagnostics_sink::{Diagnostic, DiagnosticCode, DiagnosticSink},
-        };
-
-        /// In tests, match check bails out loudly.
-        /// This helps to catch incorrect tests that pass due to false negatives.
-        pub(crate) fn report_bail_out(
-            db: &dyn HirDatabase,
-            def: DefWithBodyId,
-            pat: PatId,
-            sink: &mut DiagnosticSink,
-        ) {
-            let (_, source_map) = db.body_with_source_map(def);
-            if let Ok(source_ptr) = source_map.pat_syntax(pat) {
-                let pat_syntax_ptr = source_ptr.value.either(Into::into, Into::into);
-                sink.push(BailedOut { file: source_ptr.file_id, pat_syntax_ptr });
-            }
-        }
-
-        #[derive(Debug)]
-        struct BailedOut {
-            file: HirFileId,
-            pat_syntax_ptr: SyntaxNodePtr,
-        }
-
-        impl Diagnostic for BailedOut {
-            fn code(&self) -> DiagnosticCode {
-                DiagnosticCode("internal:match-check-bailed-out")
-            }
-            fn message(&self) -> String {
-                format!("Internal: match check bailed out")
-            }
-            fn display_source(&self) -> InFile<SyntaxNodePtr> {
-                InFile { file_id: self.file, value: self.pat_syntax_ptr.clone() }
-            }
-            fn as_any(&self) -> &(dyn Any + Send + 'static) {
-                self
-            }
-        }
-    }
-
-    use crate::diagnostics::tests::check_diagnostics;
-
-    pub(crate) use self::report::report_bail_out;
-
-    #[test]
-    fn empty_tuple() {
-        check_diagnostics(
-            r#"
-fn main() {
-    match () { }
-        //^^ Missing match arm
-    match (()) { }
-        //^^^^ Missing match arm
-
-    match () { _ => (), }
-    match () { () => (), }
-    match (()) { (()) => (), }
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn tuple_of_two_empty_tuple() {
-        check_diagnostics(
-            r#"
-fn main() {
-    match ((), ()) { }
-        //^^^^^^^^ Missing match arm
-
-    match ((), ()) { ((), ()) => (), }
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn boolean() {
-        check_diagnostics(
-            r#"
-fn test_main() {
-    match false { }
-        //^^^^^ Missing match arm
-    match false { true => (), }
-        //^^^^^ Missing match arm
-    match (false, true) {}
-        //^^^^^^^^^^^^^ Missing match arm
-    match (false, true) { (true, true) => (), }
-        //^^^^^^^^^^^^^ Missing match arm
-    match (false, true) {
-        //^^^^^^^^^^^^^ Missing match arm
-        (false, true) => (),
-        (false, false) => (),
-        (true, false) => (),
-    }
-    match (false, true) { (true, _x) => (), }
-        //^^^^^^^^^^^^^ Missing match arm
-
-    match false { true => (), false => (), }
-    match (false, true) {
-        (false, _) => (),
-        (true, false) => (),
-        (_, true) => (),
-    }
-    match (false, true) {
-        (true, true) => (),
-        (true, false) => (),
-        (false, true) => (),
-        (false, false) => (),
-    }
-    match (false, true) {
-        (true, _x) => (),
-        (false, true) => (),
-        (false, false) => (),
-    }
-    match (false, true, false) {
-        (false, ..) => (),
-        (true, ..) => (),
-    }
-    match (false, true, false) {
-        (.., false) => (),
-        (.., true) => (),
-    }
-    match (false, true, false) { (..) => (), }
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn tuple_of_tuple_and_bools() {
-        check_diagnostics(
-            r#"
-fn main() {
-    match (false, ((), false)) {}
-        //^^^^^^^^^^^^^^^^^^^^ Missing match arm
-    match (false, ((), false)) { (true, ((), true)) => (), }
-        //^^^^^^^^^^^^^^^^^^^^ Missing match arm
-    match (false, ((), false)) { (true, _) => (), }
-        //^^^^^^^^^^^^^^^^^^^^ Missing match arm
-
-    match (false, ((), false)) {
-        (true, ((), true)) => (),
-        (true, ((), false)) => (),
-        (false, ((), true)) => (),
-        (false, ((), false)) => (),
-    }
-    match (false, ((), false)) {
-        (true, ((), true)) => (),
-        (true, ((), false)) => (),
-        (false, _) => (),
-    }
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn enums() {
-        check_diagnostics(
-            r#"
-enum Either { A, B, }
-
-fn main() {
-    match Either::A { }
-        //^^^^^^^^^ Missing match arm
-    match Either::B { Either::A => (), }
-        //^^^^^^^^^ Missing match arm
-
-    match &Either::B {
-        //^^^^^^^^^^ Missing match arm
-        Either::A => (),
-    }
-
-    match Either::B {
-        Either::A => (), Either::B => (),
-    }
-    match &Either::B {
-        Either::A => (), Either::B => (),
-    }
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn enum_containing_bool() {
-        check_diagnostics(
-            r#"
-enum Either { A(bool), B }
-
-fn main() {
-    match Either::B { }
-        //^^^^^^^^^ Missing match arm
-    match Either::B {
-        //^^^^^^^^^ Missing match arm
-        Either::A(true) => (), Either::B => ()
-    }
-
-    match Either::B {
-        Either::A(true) => (),
-        Either::A(false) => (),
-        Either::B => (),
-    }
-    match Either::B {
-        Either::B => (),
-        _ => (),
-    }
-    match Either::B {
-        Either::A(_) => (),
-        Either::B => (),
-    }
-
-}
-        "#,
-        );
-    }
-
-    #[test]
-    fn enum_different_sizes() {
-        check_diagnostics(
-            r#"
-enum Either { A(bool), B(bool, bool) }
-
-fn main() {
-    match Either::A(false) {
-        //^^^^^^^^^^^^^^^^ Missing match arm
-        Either::A(_) => (),
-        Either::B(false, _) => (),
-    }
-
-    match Either::A(false) {
-        Either::A(_) => (),
-        Either::B(true, _) => (),
-        Either::B(false, _) => (),
-    }
-    match Either::A(false) {
-        Either::A(true) | Either::A(false) => (),
-        Either::B(true, _) => (),
-        Either::B(false, _) => (),
-    }
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn tuple_of_enum_no_diagnostic() {
-        check_diagnostics(
-            r#"
-enum Either { A(bool), B(bool, bool) }
-enum Either2 { C, D }
-
-fn main() {
-    match (Either::A(false), Either2::C) {
-        (Either::A(true), _) | (Either::A(false), _) => (),
-        (Either::B(true, _), Either2::C) => (),
-        (Either::B(false, _), Either2::C) => (),
-        (Either::B(_, _), Either2::D) => (),
-    }
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn or_pattern_no_diagnostic() {
-        check_diagnostics(
-            r#"
-enum Either {A, B}
-
-fn main() {
-    match (Either::A, Either::B) {
-        (Either::A | Either::B, _) => (),
-    }
-}"#,
-        )
-    }
-
-    #[test]
-    fn mismatched_types() {
-        // Match statements with arms that don't match the
-        // expression pattern do not fire this diagnostic.
-        check_diagnostics(
-            r#"
-enum Either { A, B }
-enum Either2 { C, D }
-
-fn main() {
-    match Either::A {
-        Either2::C => (),
-    //  ^^^^^^^^^^ Internal: match check bailed out
-        Either2::D => (),
-    }
-    match (true, false) {
-        (true, false, true) => (),
-    //  ^^^^^^^^^^^^^^^^^^^ Internal: match check bailed out
-        (true) => (),
-    }
-    match (true, false) { (true,) => {} }
-    //                    ^^^^^^^ Internal: match check bailed out
-    match (0) { () => () }
-            //  ^^ Internal: match check bailed out
-    match Unresolved::Bar { Unresolved::Baz => () }
-}
-        "#,
-        );
-    }
-
-    #[test]
-    fn mismatched_types_in_or_patterns() {
-        check_diagnostics(
-            r#"
-fn main() {
-    match false { true | () => {} }
-    //            ^^^^^^^^^ Internal: match check bailed out
-    match (false,) { (true | (),) => {} }
-    //               ^^^^^^^^^^^^ Internal: match check bailed out
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn malformed_match_arm_tuple_enum_missing_pattern() {
-        // We are testing to be sure we don't panic here when the match
-        // arm `Either::B` is missing its pattern.
-        check_diagnostics(
-            r#"
-enum Either { A, B(u32) }
-
-fn main() {
-    match Either::A {
-        Either::A => (),
-        Either::B() => (),
-    }
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn malformed_match_arm_extra_fields() {
-        check_diagnostics(
-            r#"
-enum A { B(isize, isize), C }
-fn main() {
-    match A::B(1, 2) {
-        A::B(_, _, _) => (),
-    //  ^^^^^^^^^^^^^ Internal: match check bailed out
-    }
-    match A::B(1, 2) {
-        A::C(_) => (),
-    //  ^^^^^^^ Internal: match check bailed out
-    }
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn expr_diverges() {
-        check_diagnostics(
-            r#"
-enum Either { A, B }
-
-fn main() {
-    match loop {} {
-        Either::A => (),
-    //  ^^^^^^^^^ Internal: match check bailed out
-        Either::B => (),
-    }
-    match loop {} {
-        Either::A => (),
-    //  ^^^^^^^^^ Internal: match check bailed out
-    }
-    match loop { break Foo::A } {
-        //^^^^^^^^^^^^^^^^^^^^^ Missing match arm
-        Either::A => (),
-    }
-    match loop { break Foo::A } {
-        Either::A => (),
-        Either::B => (),
-    }
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn expr_partially_diverges() {
-        check_diagnostics(
-            r#"
-enum Either<T> { A(T), B }
-
-fn foo() -> Either<!> { Either::B }
-fn main() -> u32 {
-    match foo() {
-        Either::A(val) => val,
-        Either::B => 0,
-    }
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn enum_record() {
-        check_diagnostics(
-            r#"
-enum Either { A { foo: bool }, B }
-
-fn main() {
-    let a = Either::A { foo: true };
-    match a { }
-        //^ Missing match arm
-    match a { Either::A { foo: true } => () }
-        //^ Missing match arm
-    match a {
-        Either::A { } => (),
-      //^^^^^^^^^ Missing structure fields:
-      //        | - foo
-        Either::B => (),
-    }
-    match a {
-        //^ Missing match arm
-        Either::A { } => (),
-    } //^^^^^^^^^ Missing structure fields:
-      //        | - foo
-
-    match a {
-        Either::A { foo: true } => (),
-        Either::A { foo: false } => (),
-        Either::B => (),
-    }
-    match a {
-        Either::A { foo: _ } => (),
-        Either::B => (),
-    }
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn enum_record_fields_out_of_order() {
-        check_diagnostics(
-            r#"
-enum Either {
-    A { foo: bool, bar: () },
-    B,
-}
-
-fn main() {
-    let a = Either::A { foo: true, bar: () };
-    match a {
-        //^ Missing match arm
-        Either::A { bar: (), foo: false } => (),
-        Either::A { foo: true, bar: () } => (),
-    }
-
-    match a {
-        Either::A { bar: (), foo: false } => (),
-        Either::A { foo: true, bar: () } => (),
-        Either::B => (),
-    }
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn enum_record_ellipsis() {
-        check_diagnostics(
-            r#"
-enum Either {
-    A { foo: bool, bar: bool },
-    B,
-}
-
-fn main() {
-    let a = Either::B;
-    match a {
-        //^ Missing match arm
-        Either::A { foo: true, .. } => (),
-        Either::B => (),
-    }
-    match a {
-        //^ Missing match arm
-        Either::A { .. } => (),
-    }
-
-    match a {
-        Either::A { foo: true, .. } => (),
-        Either::A { foo: false, .. } => (),
-        Either::B => (),
-    }
-
-    match a {
-        Either::A { .. } => (),
-        Either::B => (),
-    }
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn enum_tuple_partial_ellipsis() {
-        check_diagnostics(
-            r#"
-enum Either {
-    A(bool, bool, bool, bool),
-    B,
-}
-
-fn main() {
-    match Either::B {
-        //^^^^^^^^^ Missing match arm
-        Either::A(true, .., true) => (),
-        Either::A(true, .., false) => (),
-        Either::A(false, .., false) => (),
-        Either::B => (),
-    }
-    match Either::B {
-        //^^^^^^^^^ Missing match arm
-        Either::A(true, .., true) => (),
-        Either::A(true, .., false) => (),
-        Either::A(.., true) => (),
-        Either::B => (),
-    }
-
-    match Either::B {
-        Either::A(true, .., true) => (),
-        Either::A(true, .., false) => (),
-        Either::A(false, .., true) => (),
-        Either::A(false, .., false) => (),
-        Either::B => (),
-    }
-    match Either::B {
-        Either::A(true, .., true) => (),
-        Either::A(true, .., false) => (),
-        Either::A(.., true) => (),
-        Either::A(.., false) => (),
-        Either::B => (),
-    }
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn never() {
-        check_diagnostics(
-            r#"
-enum Never {}
-
-fn enum_(never: Never) {
-    match never {}
-}
-fn enum_ref(never: &Never) {
-    match never {}
-        //^^^^^ Missing match arm
-}
-fn bang(never: !) {
-    match never {}
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn unknown_type() {
-        check_diagnostics(
-            r#"
-enum Option<T> { Some(T), None }
-
-fn main() {
-    // `Never` is deliberately not defined so that it's an uninferred type.
-    match Option::<Never>::None {
-        None => (),
-        Some(never) => match never {},
-    //  ^^^^^^^^^^^ Internal: match check bailed out
-    }
-    match Option::<Never>::None {
-        //^^^^^^^^^^^^^^^^^^^^^ Missing match arm
-        Option::Some(_never) => {},
-    }
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn tuple_of_bools_with_ellipsis_at_end_missing_arm() {
-        check_diagnostics(
-            r#"
-fn main() {
-    match (false, true, false) {
-        //^^^^^^^^^^^^^^^^^^^^ Missing match arm
-        (false, ..) => (),
-    }
-}"#,
-        );
-    }
-
-    #[test]
-    fn tuple_of_bools_with_ellipsis_at_beginning_missing_arm() {
-        check_diagnostics(
-            r#"
-fn main() {
-    match (false, true, false) {
-        //^^^^^^^^^^^^^^^^^^^^ Missing match arm
-        (.., false) => (),
-    }
-}"#,
-        );
-    }
-
-    #[test]
-    fn tuple_of_bools_with_ellipsis_in_middle_missing_arm() {
-        check_diagnostics(
-            r#"
-fn main() {
-    match (false, true, false) {
-        //^^^^^^^^^^^^^^^^^^^^ Missing match arm
-        (true, .., false) => (),
-    }
-}"#,
-        );
-    }
-
-    #[test]
-    fn record_struct() {
-        check_diagnostics(
-            r#"struct Foo { a: bool }
-fn main(f: Foo) {
-    match f {}
-        //^ Missing match arm
-    match f { Foo { a: true } => () }
-        //^ Missing match arm
-    match &f { Foo { a: true } => () }
-        //^^ Missing match arm
-    match f { Foo { a: _ } => () }
-    match f {
-        Foo { a: true } => (),
-        Foo { a: false } => (),
-    }
-    match &f {
-        Foo { a: true } => (),
-        Foo { a: false } => (),
-    }
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn tuple_struct() {
-        check_diagnostics(
-            r#"struct Foo(bool);
-fn main(f: Foo) {
-    match f {}
-        //^ Missing match arm
-    match f { Foo(true) => () }
-        //^ Missing match arm
-    match f {
-        Foo(true) => (),
-        Foo(false) => (),
-    }
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn unit_struct() {
-        check_diagnostics(
-            r#"struct Foo;
-fn main(f: Foo) {
-    match f {}
-        //^ Missing match arm
-    match f { Foo => () }
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn record_struct_ellipsis() {
-        check_diagnostics(
-            r#"struct Foo { foo: bool, bar: bool }
-fn main(f: Foo) {
-    match f { Foo { foo: true, .. } => () }
-        //^ Missing match arm
-    match f {
-        //^ Missing match arm
-        Foo { foo: true, .. } => (),
-        Foo { bar: false, .. } => ()
-    }
-    match f { Foo { .. } => () }
-    match f {
-        Foo { foo: true, .. } => (),
-        Foo { foo: false, .. } => ()
-    }
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn internal_or() {
-        check_diagnostics(
-            r#"
-fn main() {
-    enum Either { A(bool), B }
-    match Either::B {
-        //^^^^^^^^^ Missing match arm
-        Either::A(true | false) => (),
-    }
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn no_panic_at_unimplemented_subpattern_type() {
-        check_diagnostics(
-            r#"
-struct S { a: char}
-fn main(v: S) {
-    match v { S{ a }      => {} }
-    match v { S{ a: _x }  => {} }
-    match v { S{ a: 'a' } => {} }
-            //^^^^^^^^^^^ Internal: match check bailed out
-    match v { S{..}       => {} }
-    match v { _           => {} }
-    match v { }
-        //^ Missing match arm
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn binding() {
-        check_diagnostics(
-            r#"
-fn main() {
-    match true {
-        _x @ true => {}
-        false     => {}
-    }
-    match true { _x @ true => {} }
-        //^^^^ Missing match arm
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn binding_ref_has_correct_type() {
-        // Asserts `PatKind::Binding(ref _x): bool`, not &bool.
-        // If that's not true match checking will panic with "incompatible constructors"
-        // FIXME: make facilities to test this directly like `tests::check_infer(..)`
-        check_diagnostics(
-            r#"
-enum Foo { A }
-fn main() {
-    // FIXME: this should not bail out but current behavior is such as the old algorithm.
-    // ExprValidator::validate_match(..) checks types of top level patterns incorrecly.
-    match Foo::A {
-        ref _x => {}
-    //  ^^^^^^ Internal: match check bailed out
-        Foo::A => {}
-    }
-    match (true,) {
-        (ref _x,) => {}
-        (true,) => {}
-    }
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn enum_non_exhaustive() {
-        check_diagnostics(
-            r#"
-//- /lib.rs crate:lib
-#[non_exhaustive]
-pub enum E { A, B }
-fn _local() {
-    match E::A { _ => {} }
-    match E::A {
-        E::A => {}
-        E::B => {}
-    }
-    match E::A {
-        E::A | E::B => {}
-    }
-}
-
-//- /main.rs crate:main deps:lib
-use lib::E;
-fn main() {
-    match E::A { _ => {} }
-    match E::A {
-        //^^^^ Missing match arm
-        E::A => {}
-        E::B => {}
-    }
-    match E::A {
-        //^^^^ Missing match arm
-        E::A | E::B => {}
-    }
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn match_guard() {
-        check_diagnostics(
-            r#"
-fn main() {
-    match true {
-        true if false => {}
-        true          => {}
-        false         => {}
-    }
-    match true {
-        //^^^^ Missing match arm
-        true if false => {}
-        false         => {}
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn pattern_type_is_of_substitution() {
-        cov_mark::check!(match_check_wildcard_expanded_to_substitutions);
-        check_diagnostics(
-            r#"
-struct Foo<T>(T);
-struct Bar;
-fn main() {
-    match Foo(Bar) {
-        _ | Foo(Bar) => {}
-    }
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn record_struct_no_such_field() {
-        check_diagnostics(
-            r#"
-struct Foo { }
-fn main(f: Foo) {
-    match f { Foo { bar } => () }
-    //        ^^^^^^^^^^^ Internal: match check bailed out
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn match_ergonomics_issue_9095() {
-        check_diagnostics(
-            r#"
-enum Foo<T> { A(T) }
-fn main() {
-    match &Foo::A(true) {
-        _ => {}
-        Foo::A(_) => {}
-    }
-}
-"#,
-        );
-    }
-
-    mod false_negatives {
-        //! The implementation of match checking here is a work in progress. As we roll this out, we
-        //! prefer false negatives to false positives (ideally there would be no false positives). This
-        //! test module should document known false negatives. Eventually we will have a complete
-        //! implementation of match checking and this module will be empty.
-        //!
-        //! The reasons for documenting known false negatives:
-        //!
-        //!   1. It acts as a backlog of work that can be done to improve the behavior of the system.
-        //!   2. It ensures the code doesn't panic when handling these cases.
-        use super::*;
-
-        #[test]
-        fn integers() {
-            // We don't currently check integer exhaustiveness.
-            check_diagnostics(
-                r#"
-fn main() {
-    match 5 {
-        10 => (),
-    //  ^^ Internal: match check bailed out
-        11..20 => (),
-    }
-}
-"#,
-            );
-        }
-
-        #[test]
-        fn reference_patterns_at_top_level() {
-            check_diagnostics(
-                r#"
-fn main() {
-    match &false {
-        &true => {}
-    //  ^^^^^ Internal: match check bailed out
-    }
-}
-            "#,
-            );
-        }
-
-        #[test]
-        fn reference_patterns_in_fields() {
-            check_diagnostics(
-                r#"
-fn main() {
-    match (&false,) {
-        (true,) => {}
-    //  ^^^^^^^ Internal: match check bailed out
-    }
-    match (&false,) {
-        (&true,) => {}
-    //  ^^^^^^^^ Internal: match check bailed out
-    }
-}
-            "#,
-            );
-        }
-    }
-}
diff --git a/crates/hir_ty/src/diagnostics/match_check/deconstruct_pat.rs b/crates/hir_ty/src/diagnostics/match_check/deconstruct_pat.rs
index 1f4219b42..471cd4921 100644
--- a/crates/hir_ty/src/diagnostics/match_check/deconstruct_pat.rs
+++ b/crates/hir_ty/src/diagnostics/match_check/deconstruct_pat.rs
@@ -528,7 +528,7 @@ impl SplitWildcard {
                 smallvec![NonExhaustive]
             }
             TyKind::Never => SmallVec::new(),
-            _ if cx.is_uninhabited(&pcx.ty) => SmallVec::new(),
+            _ if cx.is_uninhabited(pcx.ty) => SmallVec::new(),
             TyKind::Adt(..) | TyKind::Tuple(..) | TyKind::Ref(..) => smallvec![Single],
             // This type is one for which we cannot list constructors, like `str` or `f64`.
             _ => smallvec![NonExhaustive],
diff --git a/crates/hir_ty/src/diagnostics/match_check/usefulness.rs b/crates/hir_ty/src/diagnostics/match_check/usefulness.rs
index bd76a606c..8451f9df5 100644
--- a/crates/hir_ty/src/diagnostics/match_check/usefulness.rs
+++ b/crates/hir_ty/src/diagnostics/match_check/usefulness.rs
@@ -1,5 +1,5 @@
 //! Based on rust-lang/rust 1.52.0-nightly (25c15cdbe 2021-04-22)
-//! https://github.com/rust-lang/rust/blob/25c15cdbe/compiler/rustc_mir_build/src/thir/pattern/usefulness.rs
+//! <https://github.com/rust-lang/rust/blob/25c15cdbe/compiler/rustc_mir_build/src/thir/pattern/usefulness.rs>
 //!
 //! -----
 //!
@@ -645,7 +645,7 @@ impl SubPatSet {
             (Seq { subpats: s_set }, Seq { subpats: mut o_set }) => {
                 s_set.retain(|i, s_sub_set| {
                     // Missing entries count as full.
-                    let o_sub_set = o_set.remove(&i).unwrap_or(Full);
+                    let o_sub_set = o_set.remove(i).unwrap_or(Full);
                     s_sub_set.union(o_sub_set);
                     // We drop full entries.
                     !s_sub_set.is_full()
@@ -656,7 +656,7 @@ impl SubPatSet {
             (Alt { subpats: s_set, .. }, Alt { subpats: mut o_set, .. }) => {
                 s_set.retain(|i, s_sub_set| {
                     // Missing entries count as empty.
-                    let o_sub_set = o_set.remove(&i).unwrap_or(Empty);
+                    let o_sub_set = o_set.remove(i).unwrap_or(Empty);
                     s_sub_set.union(o_sub_set);
                     // We drop empty entries.
                     !s_sub_set.is_empty()
@@ -898,7 +898,7 @@ impl Usefulness {
                 } else {
                     witnesses
                         .into_iter()
-                        .map(|witness| witness.apply_constructor(pcx, &ctor, ctor_wild_subpatterns))
+                        .map(|witness| witness.apply_constructor(pcx, ctor, ctor_wild_subpatterns))
                         .collect()
                 };
                 WithWitnesses(new_witnesses)
diff --git a/crates/hir_ty/src/diagnostics/unsafe_check.rs b/crates/hir_ty/src/diagnostics/unsafe_check.rs
index c3c483425..777f347b8 100644
--- a/crates/hir_ty/src/diagnostics/unsafe_check.rs
+++ b/crates/hir_ty/src/diagnostics/unsafe_check.rs
@@ -1,8 +1,6 @@
 //! Provides validations for unsafe code. Currently checks if unsafe functions are missing
 //! unsafe blocks.
 
-use std::sync::Arc;
-
 use hir_def::{
     body::Body,
     expr::{Expr, ExprId, UnaryOp},
@@ -10,60 +8,32 @@ use hir_def::{
     DefWithBodyId,
 };
 
-use crate::{
-    db::HirDatabase, diagnostics::MissingUnsafe, diagnostics_sink::DiagnosticSink, InferenceResult,
-    Interner, TyExt, TyKind,
-};
+use crate::{db::HirDatabase, InferenceResult, Interner, TyExt, TyKind};
 
-pub(super) struct UnsafeValidator<'a, 'b: 'a> {
-    owner: DefWithBodyId,
-    infer: Arc<InferenceResult>,
-    sink: &'a mut DiagnosticSink<'b>,
-}
+pub fn missing_unsafe(db: &dyn HirDatabase, def: DefWithBodyId) -> Vec<ExprId> {
+    let infer = db.infer(def);
 
-impl<'a, 'b> UnsafeValidator<'a, 'b> {
-    pub(super) fn new(
-        owner: DefWithBodyId,
-        infer: Arc<InferenceResult>,
-        sink: &'a mut DiagnosticSink<'b>,
-    ) -> UnsafeValidator<'a, 'b> {
-        UnsafeValidator { owner, infer, sink }
+    let is_unsafe = match def {
+        DefWithBodyId::FunctionId(it) => db.function_data(it).is_unsafe(),
+        DefWithBodyId::StaticId(_) | DefWithBodyId::ConstId(_) => false,
+    };
+    if is_unsafe {
+        return Vec::new();
     }
 
-    pub(super) fn validate_body(&mut self, db: &dyn HirDatabase) {
-        let def = self.owner;
-        let unsafe_expressions = unsafe_expressions(db, self.infer.as_ref(), def);
-        let is_unsafe = match self.owner {
-            DefWithBodyId::FunctionId(it) => db.function_data(it).is_unsafe(),
-            DefWithBodyId::StaticId(_) | DefWithBodyId::ConstId(_) => false,
-        };
-        if is_unsafe
-            || unsafe_expressions
-                .iter()
-                .filter(|unsafe_expr| !unsafe_expr.inside_unsafe_block)
-                .count()
-                == 0
-        {
-            return;
-        }
-
-        let (_, body_source) = db.body_with_source_map(def);
-        for unsafe_expr in unsafe_expressions {
-            if !unsafe_expr.inside_unsafe_block {
-                if let Ok(in_file) = body_source.as_ref().expr_syntax(unsafe_expr.expr) {
-                    self.sink.push(MissingUnsafe { file: in_file.file_id, expr: in_file.value })
-                }
-            }
-        }
-    }
+    unsafe_expressions(db, &infer, def)
+        .into_iter()
+        .filter(|it| !it.inside_unsafe_block)
+        .map(|it| it.expr)
+        .collect()
 }
 
-pub(crate) struct UnsafeExpr {
+struct UnsafeExpr {
     pub(crate) expr: ExprId,
     pub(crate) inside_unsafe_block: bool,
 }
 
-pub(crate) fn unsafe_expressions(
+fn unsafe_expressions(
     db: &dyn HirDatabase,
     infer: &InferenceResult,
     def: DefWithBodyId,
@@ -126,92 +96,3 @@ fn walk_unsafe(
         walk_unsafe(unsafe_exprs, db, infer, def, body, child, inside_unsafe_block);
     });
 }
-
-#[cfg(test)]
-mod tests {
-    use crate::diagnostics::tests::check_diagnostics;
-
-    #[test]
-    fn missing_unsafe_diagnostic_with_raw_ptr() {
-        check_diagnostics(
-            r#"
-fn main() {
-    let x = &5 as *const usize;
-    unsafe { let y = *x; }
-    let z = *x;
-}         //^^ This operation is unsafe and requires an unsafe function or block
-"#,
-        )
-    }
-
-    #[test]
-    fn missing_unsafe_diagnostic_with_unsafe_call() {
-        check_diagnostics(
-            r#"
-struct HasUnsafe;
-
-impl HasUnsafe {
-    unsafe fn unsafe_fn(&self) {
-        let x = &5 as *const usize;
-        let y = *x;
-    }
-}
-
-unsafe fn unsafe_fn() {
-    let x = &5 as *const usize;
-    let y = *x;
-}
-
-fn main() {
-    unsafe_fn();
-  //^^^^^^^^^^^ This operation is unsafe and requires an unsafe function or block
-    HasUnsafe.unsafe_fn();
-  //^^^^^^^^^^^^^^^^^^^^^ This operation is unsafe and requires an unsafe function or block
-    unsafe {
-        unsafe_fn();
-        HasUnsafe.unsafe_fn();
-    }
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn missing_unsafe_diagnostic_with_static_mut() {
-        check_diagnostics(
-            r#"
-struct Ty {
-    a: u8,
-}
-
-static mut STATIC_MUT: Ty = Ty { a: 0 };
-
-fn main() {
-    let x = STATIC_MUT.a;
-          //^^^^^^^^^^ This operation is unsafe and requires an unsafe function or block
-    unsafe {
-        let x = STATIC_MUT.a;
-    }
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn no_missing_unsafe_diagnostic_with_safe_intrinsic() {
-        check_diagnostics(
-            r#"
-extern "rust-intrinsic" {
-    pub fn bitreverse(x: u32) -> u32; // Safe intrinsic
-    pub fn floorf32(x: f32) -> f32; // Unsafe intrinsic
-}
-
-fn main() {
-    let _ = bitreverse(12);
-    let _ = floorf32(12.0);
-          //^^^^^^^^^^^^^^ This operation is unsafe and requires an unsafe function or block
-}
-"#,
-        );
-    }
-}
diff --git a/crates/hir_ty/src/diagnostics_sink.rs b/crates/hir_ty/src/diagnostics_sink.rs
deleted file mode 100644
index 084fa8b06..000000000
--- a/crates/hir_ty/src/diagnostics_sink.rs
+++ /dev/null
@@ -1,109 +0,0 @@
-//! Semantic errors and warnings.
-//!
-//! The `Diagnostic` trait defines a trait object which can represent any
-//! diagnostic.
-//!
-//! `DiagnosticSink` struct is used as an emitter for diagnostic. When creating
-//! a `DiagnosticSink`, you supply a callback which can react to a `dyn
-//! Diagnostic` or to any concrete diagnostic (downcasting is used internally).
-//!
-//! Because diagnostics store file offsets, it's a bad idea to store them
-//! directly in salsa. For this reason, every hir subsytem defines it's own
-//! strongly-typed closed set of diagnostics which use hir ids internally, are
-//! stored in salsa and do *not* implement the `Diagnostic` trait. Instead, a
-//! subsystem provides a separate, non-query-based API which can walk all stored
-//! values and transform them into instances of `Diagnostic`.
-
-use std::{any::Any, fmt};
-
-use hir_expand::InFile;
-use syntax::SyntaxNodePtr;
-
-#[derive(Copy, Clone, Debug, PartialEq)]
-pub struct DiagnosticCode(pub &'static str);
-
-impl DiagnosticCode {
-    pub fn as_str(&self) -> &str {
-        self.0
-    }
-}
-
-pub trait Diagnostic: Any + Send + Sync + fmt::Debug + 'static {
-    fn code(&self) -> DiagnosticCode;
-    fn message(&self) -> String;
-    /// Source element that triggered the diagnostics.
-    ///
-    /// Note that this should reflect "semantics", rather than specific span we
-    /// want to highlight. When rendering the diagnostics into an error message,
-    /// the IDE will fetch the `SyntaxNode` and will narrow the span
-    /// appropriately.
-    fn display_source(&self) -> InFile<SyntaxNodePtr>;
-    fn as_any(&self) -> &(dyn Any + Send + 'static);
-    fn is_experimental(&self) -> bool {
-        false
-    }
-}
-
-pub struct DiagnosticSink<'a> {
-    callbacks: Vec<Box<dyn FnMut(&dyn Diagnostic) -> Result<(), ()> + 'a>>,
-    filters: Vec<Box<dyn FnMut(&dyn Diagnostic) -> bool + 'a>>,
-    default_callback: Box<dyn FnMut(&dyn Diagnostic) + 'a>,
-}
-
-impl<'a> DiagnosticSink<'a> {
-    pub fn push(&mut self, d: impl Diagnostic) {
-        let d: &dyn Diagnostic = &d;
-        self._push(d);
-    }
-
-    fn _push(&mut self, d: &dyn Diagnostic) {
-        for filter in &mut self.filters {
-            if !filter(d) {
-                return;
-            }
-        }
-        for cb in &mut self.callbacks {
-            match cb(d) {
-                Ok(()) => return,
-                Err(()) => (),
-            }
-        }
-        (self.default_callback)(d)
-    }
-}
-
-pub struct DiagnosticSinkBuilder<'a> {
-    callbacks: Vec<Box<dyn FnMut(&dyn Diagnostic) -> Result<(), ()> + 'a>>,
-    filters: Vec<Box<dyn FnMut(&dyn Diagnostic) -> bool + 'a>>,
-}
-
-impl<'a> DiagnosticSinkBuilder<'a> {
-    pub fn new() -> Self {
-        Self { callbacks: Vec::new(), filters: Vec::new() }
-    }
-
-    pub fn filter<F: FnMut(&dyn Diagnostic) -> bool + 'a>(mut self, cb: F) -> Self {
-        self.filters.push(Box::new(cb));
-        self
-    }
-
-    pub fn on<D: Diagnostic, F: FnMut(&D) + 'a>(mut self, mut cb: F) -> Self {
-        let cb = move |diag: &dyn Diagnostic| match diag.as_any().downcast_ref::<D>() {
-            Some(d) => {
-                cb(d);
-                Ok(())
-            }
-            None => Err(()),
-        };
-        self.callbacks.push(Box::new(cb));
-        self
-    }
-
-    pub fn build<F: FnMut(&dyn Diagnostic) + 'a>(self, default_callback: F) -> DiagnosticSink<'a> {
-        DiagnosticSink {
-            callbacks: self.callbacks,
-            filters: self.filters,
-            default_callback: Box::new(default_callback),
-        }
-    }
-}
diff --git a/crates/hir_ty/src/infer.rs b/crates/hir_ty/src/infer.rs
index 0e9f777da..63f37c0ab 100644
--- a/crates/hir_ty/src/infer.rs
+++ b/crates/hir_ty/src/infer.rs
@@ -35,11 +35,9 @@ use stdx::impl_from;
 use syntax::SmolStr;
 
 use super::{DomainGoal, InEnvironment, ProjectionTy, TraitEnvironment, TraitRef, Ty};
-use crate::diagnostics_sink::DiagnosticSink;
 use crate::{
-    db::HirDatabase, fold_tys, infer::diagnostics::InferenceDiagnostic,
-    lower::ImplTraitLoweringMode, to_assoc_type_id, AliasEq, AliasTy, Goal, Interner, Substitution,
-    TyBuilder, TyExt, TyKind,
+    db::HirDatabase, fold_tys, lower::ImplTraitLoweringMode, to_assoc_type_id, AliasEq, AliasTy,
+    Goal, Interner, Substitution, TyBuilder, TyExt, TyKind,
 };
 
 // This lint has a false positive here. See the link below for details.
@@ -80,7 +78,7 @@ enum ExprOrPatId {
 impl_from!(ExprId, PatId for ExprOrPatId);
 
 /// Binding modes inferred for patterns.
-/// https://doc.rust-lang.org/reference/patterns.html#binding-modes
+/// <https://doc.rust-lang.org/reference/patterns.html#binding-modes>
 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
 enum BindingMode {
     Move,
@@ -111,6 +109,12 @@ pub(crate) struct InferOk {
 pub(crate) struct TypeError;
 pub(crate) type InferResult = Result<InferOk, TypeError>;
 
+#[derive(Debug, PartialEq, Eq, Clone)]
+pub enum InferenceDiagnostic {
+    NoSuchField { expr: ExprId },
+    BreakOutsideOfLoop { expr: ExprId },
+}
+
 /// A mismatch between an expected and an inferred type.
 #[derive(Clone, PartialEq, Eq, Debug, Hash)]
 pub struct TypeMismatch {
@@ -140,7 +144,7 @@ pub struct InferenceResult {
     variant_resolutions: FxHashMap<ExprOrPatId, VariantId>,
     /// For each associated item record what it resolves to
     assoc_resolutions: FxHashMap<ExprOrPatId, AssocItemId>,
-    diagnostics: Vec<InferenceDiagnostic>,
+    pub diagnostics: Vec<InferenceDiagnostic>,
     pub type_of_expr: ArenaMap<ExprId, Ty>,
     /// For each pattern record the type it resolves to.
     ///
@@ -191,14 +195,6 @@ impl InferenceResult {
             _ => None,
         })
     }
-    pub fn add_diagnostics(
-        &self,
-        db: &dyn HirDatabase,
-        owner: DefWithBodyId,
-        sink: &mut DiagnosticSink,
-    ) {
-        self.diagnostics.iter().for_each(|it| it.add_to(db, owner, sink))
-    }
 }
 
 impl Index<ExprId> for InferenceResult {
@@ -765,6 +761,38 @@ impl Expectation {
             Expectation::RValueLikeUnsized(_) | Expectation::None => None,
         }
     }
+
+    /// Comment copied from rustc:
+    /// Disregard "castable to" expectations because they
+    /// can lead us astray. Consider for example `if cond
+    /// {22} else {c} as u8` -- if we propagate the
+    /// "castable to u8" constraint to 22, it will pick the
+    /// type 22u8, which is overly constrained (c might not
+    /// be a u8). In effect, the problem is that the
+    /// "castable to" expectation is not the tightest thing
+    /// we can say, so we want to drop it in this case.
+    /// The tightest thing we can say is "must unify with
+    /// else branch". Note that in the case of a "has type"
+    /// constraint, this limitation does not hold.
+    ///
+    /// If the expected type is just a type variable, then don't use
+    /// an expected type. Otherwise, we might write parts of the type
+    /// when checking the 'then' block which are incompatible with the
+    /// 'else' branch.
+    fn adjust_for_branches(&self, table: &mut unify::InferenceTable) -> Expectation {
+        match self {
+            Expectation::HasType(ety) => {
+                let ety = table.resolve_ty_shallow(ety);
+                if !ety.is_ty_var() {
+                    Expectation::HasType(ety)
+                } else {
+                    Expectation::None
+                }
+            }
+            Expectation::RValueLikeUnsized(ety) => Expectation::RValueLikeUnsized(ety.clone()),
+            _ => Expectation::None,
+        }
+    }
 }
 
 #[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord)]
@@ -804,43 +832,3 @@ impl std::ops::BitOrAssign for Diverges {
         *self = *self | other;
     }
 }
-
-mod diagnostics {
-    use hir_def::{expr::ExprId, DefWithBodyId};
-
-    use crate::{
-        db::HirDatabase,
-        diagnostics::{BreakOutsideOfLoop, NoSuchField},
-        diagnostics_sink::DiagnosticSink,
-    };
-
-    #[derive(Debug, PartialEq, Eq, Clone)]
-    pub(super) enum InferenceDiagnostic {
-        NoSuchField { expr: ExprId },
-        BreakOutsideOfLoop { expr: ExprId },
-    }
-
-    impl InferenceDiagnostic {
-        pub(super) fn add_to(
-            &self,
-            db: &dyn HirDatabase,
-            owner: DefWithBodyId,
-            sink: &mut DiagnosticSink,
-        ) {
-            match self {
-                InferenceDiagnostic::NoSuchField { expr } => {
-                    let (_, source_map) = db.body_with_source_map(owner);
-                    let field = source_map.field_syntax(*expr);
-                    sink.push(NoSuchField { file: field.file_id, field: field.value })
-                }
-                InferenceDiagnostic::BreakOutsideOfLoop { expr } => {
-                    let (_, source_map) = db.body_with_source_map(owner);
-                    let ptr = source_map
-                        .expr_syntax(*expr)
-                        .expect("break outside of loop in synthetic syntax");
-                    sink.push(BreakOutsideOfLoop { file: ptr.file_id, expr: ptr.value })
-                }
-            }
-        }
-    }
-}
diff --git a/crates/hir_ty/src/infer/coerce.rs b/crates/hir_ty/src/infer/coerce.rs
index 03b97e7db..4b7f31521 100644
--- a/crates/hir_ty/src/infer/coerce.rs
+++ b/crates/hir_ty/src/infer/coerce.rs
@@ -2,8 +2,8 @@
 //! 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 and
-//! librustc_typeck/check/coercion.rs.
+//! See <https://doc.rust-lang.org/nomicon/coercions.html> and
+//! `librustc_typeck/check/coercion.rs`.
 
 use chalk_ir::{cast::Cast, Mutability, TyVariableKind};
 use hir_def::{expr::ExprId, lang_item::LangItemTarget};
@@ -109,7 +109,7 @@ impl<'a> InferenceContext<'a> {
         }
 
         // Consider coercing the subtype to a DST
-        if let Ok(ret) = self.try_coerce_unsized(&from_ty, &to_ty) {
+        if let Ok(ret) = self.try_coerce_unsized(&from_ty, to_ty) {
             return Ok(ret);
         }
 
@@ -331,7 +331,7 @@ impl<'a> InferenceContext<'a> {
 
     /// Coerce a type using `from_ty: CoerceUnsized<ty_ty>`
     ///
-    /// See: https://doc.rust-lang.org/nightly/std/marker/trait.CoerceUnsized.html
+    /// See: <https://doc.rust-lang.org/nightly/std/marker/trait.CoerceUnsized.html>
     fn try_coerce_unsized(&mut self, from_ty: &Ty, to_ty: &Ty) -> InferResult {
         // These 'if' statements require some explanation.
         // The `CoerceUnsized` trait is special - it is only
diff --git a/crates/hir_ty/src/infer/expr.rs b/crates/hir_ty/src/infer/expr.rs
index f73bf43b2..5ea2e5934 100644
--- a/crates/hir_ty/src/infer/expr.rs
+++ b/crates/hir_ty/src/infer/expr.rs
@@ -54,7 +54,7 @@ impl<'a> InferenceContext<'a> {
     /// Infer type of expression with possibly implicit coerce to the expected type.
     /// Return the type after possible coercion.
     pub(super) fn infer_expr_coerce(&mut self, expr: ExprId, expected: &Expectation) -> Ty {
-        let ty = self.infer_expr_inner(expr, &expected);
+        let ty = self.infer_expr_inner(expr, expected);
         let ty = if let Some(target) = expected.only_has_type(&mut self.table) {
             if !self.coerce(&ty, &target) {
                 self.result
@@ -135,11 +135,11 @@ impl<'a> InferenceContext<'a> {
                 let mut both_arms_diverge = Diverges::Always;
 
                 let mut result_ty = self.table.new_type_var();
-                let then_ty = self.infer_expr_inner(*then_branch, &expected);
+                let then_ty = self.infer_expr_inner(*then_branch, expected);
                 both_arms_diverge &= mem::replace(&mut self.diverges, Diverges::Maybe);
                 result_ty = self.coerce_merge_branch(Some(*then_branch), &result_ty, &then_ty);
                 let else_ty = match else_branch {
-                    Some(else_branch) => self.infer_expr_inner(*else_branch, &expected),
+                    Some(else_branch) => self.infer_expr_inner(*else_branch, expected),
                     None => TyBuilder::unit(),
                 };
                 both_arms_diverge &= self.diverges;
@@ -327,20 +327,19 @@ impl<'a> InferenceContext<'a> {
                 self.normalize_associated_types_in(ret_ty)
             }
             Expr::MethodCall { receiver, args, method_name, generic_args } => self
-                .infer_method_call(
-                    tgt_expr,
-                    *receiver,
-                    &args,
-                    &method_name,
-                    generic_args.as_deref(),
-                ),
+                .infer_method_call(tgt_expr, *receiver, args, method_name, generic_args.as_deref()),
             Expr::Match { expr, arms } => {
                 let input_ty = self.infer_expr(*expr, &Expectation::none());
 
+                let expected = expected.adjust_for_branches(&mut self.table);
+
                 let mut result_ty = if arms.is_empty() {
                     TyKind::Never.intern(&Interner)
                 } else {
-                    self.table.new_type_var()
+                    match &expected {
+                        Expectation::HasType(ty) => ty.clone(),
+                        _ => self.table.new_type_var(),
+                    }
                 };
 
                 let matchee_diverges = self.diverges;
@@ -988,7 +987,7 @@ impl<'a> InferenceContext<'a> {
     }
 
     fn register_obligations_for_call(&mut self, callable_ty: &Ty) {
-        let callable_ty = self.resolve_ty_shallow(&callable_ty);
+        let callable_ty = self.resolve_ty_shallow(callable_ty);
         if let TyKind::FnDef(fn_def, parameters) = callable_ty.kind(&Interner) {
             let def: CallableDefId = from_chalk(self.db, *fn_def);
             let generic_predicates = self.db.generic_predicates(def.into());
diff --git a/crates/hir_ty/src/infer/pat.rs b/crates/hir_ty/src/infer/pat.rs
index 25dff7e49..035f4ded6 100644
--- a/crates/hir_ty/src/infer/pat.rs
+++ b/crates/hir_ty/src/infer/pat.rs
@@ -192,7 +192,7 @@ impl<'a> InferenceContext<'a> {
             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(self.err_ty())
+                self.infer_path(&resolver, path, pat.into()).unwrap_or(self.err_ty())
             }
             Pat::Bind { mode, name: _, subpat } => {
                 let mode = if mode == &BindingAnnotation::Unannotated {
@@ -275,7 +275,7 @@ impl<'a> InferenceContext<'a> {
         if !self.unify(&ty, &expected) {
             self.result
                 .type_mismatches
-                .insert(pat.into(), TypeMismatch { expected: expected, actual: ty.clone() });
+                .insert(pat.into(), TypeMismatch { expected, actual: ty.clone() });
         }
         self.write_pat_ty(pat, ty.clone());
         ty
diff --git a/crates/hir_ty/src/infer/path.rs b/crates/hir_ty/src/infer/path.rs
index 14c99eafd..056cdb5d5 100644
--- a/crates/hir_ty/src/infer/path.rs
+++ b/crates/hir_ty/src/infer/path.rs
@@ -43,11 +43,11 @@ impl<'a> InferenceContext<'a> {
             }
             let ty = self.make_ty(type_ref);
             let remaining_segments_for_ty = path.segments().take(path.segments().len() - 1);
-            let ctx = crate::lower::TyLoweringContext::new(self.db, &resolver);
+            let ctx = crate::lower::TyLoweringContext::new(self.db, resolver);
             let (ty, _) = ctx.lower_ty_relative_path(ty, None, remaining_segments_for_ty);
             self.resolve_ty_assoc_item(
                 ty,
-                &path.segments().last().expect("path had at least one segment").name,
+                path.segments().last().expect("path had at least one segment").name,
                 id,
             )?
         } else {
@@ -154,7 +154,7 @@ impl<'a> InferenceContext<'a> {
                 let segment =
                     remaining_segments.last().expect("there should be at least one segment here");
 
-                self.resolve_ty_assoc_item(ty, &segment.name, id)
+                self.resolve_ty_assoc_item(ty, segment.name, id)
             }
         }
     }
diff --git a/crates/hir_ty/src/interner.rs b/crates/hir_ty/src/interner.rs
index 29ffdd9b7..5fef878e8 100644
--- a/crates/hir_ty/src/interner.rs
+++ b/crates/hir_ty/src/interner.rs
@@ -331,7 +331,7 @@ impl chalk_ir::interner::Interner for Interner {
         &self,
         clauses: &'a Self::InternedProgramClauses,
     ) -> &'a [chalk_ir::ProgramClause<Self>] {
-        &clauses
+        clauses
     }
 
     fn intern_quantified_where_clauses<E>(
@@ -373,7 +373,7 @@ impl chalk_ir::interner::Interner for Interner {
         &self,
         canonical_var_kinds: &'a Self::InternedCanonicalVarKinds,
     ) -> &'a [chalk_ir::CanonicalVarKind<Self>] {
-        &canonical_var_kinds
+        canonical_var_kinds
     }
 
     fn intern_constraints<E>(
@@ -413,7 +413,7 @@ impl chalk_ir::interner::Interner for Interner {
         &self,
         variances: &'a Self::InternedVariances,
     ) -> &'a [chalk_ir::Variance] {
-        &variances
+        variances
     }
 }
 
diff --git a/crates/hir_ty/src/lib.rs b/crates/hir_ty/src/lib.rs
index 50e0d6333..128cae830 100644
--- a/crates/hir_ty/src/lib.rs
+++ b/crates/hir_ty/src/lib.rs
@@ -21,7 +21,6 @@ mod utils;
 mod walk;
 pub mod db;
 pub mod diagnostics;
-pub mod diagnostics_sink;
 pub mod display;
 pub mod method_resolution;
 pub mod primitive;
@@ -50,7 +49,7 @@ use crate::{db::HirDatabase, utils::generics};
 pub use autoderef::autoderef;
 pub use builder::TyBuilder;
 pub use chalk_ext::*;
-pub use infer::{could_unify, InferenceResult};
+pub use infer::{could_unify, InferenceDiagnostic, InferenceResult};
 pub use interner::Interner;
 pub use lower::{
     associated_type_shorthand_candidates, callable_item_sig, CallableDefId, ImplTraitLoweringMode,
diff --git a/crates/hir_ty/src/lower.rs b/crates/hir_ty/src/lower.rs
index c83933c73..817a65c20 100644
--- a/crates/hir_ty/src/lower.rs
+++ b/crates/hir_ty/src/lower.rs
@@ -238,7 +238,7 @@ impl<'a> TyLoweringContext<'a> {
                         // away instead of two.
                         let actual_opaque_type_data = self
                             .with_debruijn(DebruijnIndex::INNERMOST, |ctx| {
-                                ctx.lower_impl_trait(&bounds)
+                                ctx.lower_impl_trait(bounds)
                             });
                         self.opaque_type_data.borrow_mut()[idx as usize] = actual_opaque_type_data;
 
@@ -421,7 +421,7 @@ impl<'a> TyLoweringContext<'a> {
                     let found = self
                         .db
                         .trait_data(trait_ref.hir_trait_id())
-                        .associated_type_by_name(&segment.name);
+                        .associated_type_by_name(segment.name);
                     match found {
                         Some(associated_ty) => {
                             // FIXME handle type parameters on the segment
@@ -505,7 +505,7 @@ impl<'a> TyLoweringContext<'a> {
     pub(crate) fn lower_path(&self, path: &Path) -> (Ty, Option<TypeNs>) {
         // Resolve the path (in type namespace)
         if let Some(type_ref) = path.type_anchor() {
-            let (ty, res) = self.lower_ty_ext(&type_ref);
+            let (ty, res) = self.lower_ty_ext(type_ref);
             return self.lower_ty_relative_path(ty, res, path.segments());
         }
         let (resolution, remaining_index) =
@@ -784,7 +784,7 @@ impl<'a> TyLoweringContext<'a> {
         let trait_ref = match bound {
             TypeBound::Path(path) => {
                 bindings = self.lower_trait_ref_from_path(path, Some(self_ty));
-                bindings.clone().map(WhereClause::Implemented).map(|b| crate::wrap_empty_binders(b))
+                bindings.clone().map(WhereClause::Implemented).map(crate::wrap_empty_binders)
             }
             TypeBound::Lifetime(_) => None,
             TypeBound::Error => None,
@@ -957,7 +957,7 @@ pub(crate) fn field_types_query(
 /// 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
+/// <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<()>`.
diff --git a/crates/hir_ty/src/method_resolution.rs b/crates/hir_ty/src/method_resolution.rs
index a23527f7d..3d233b1e2 100644
--- a/crates/hir_ty/src/method_resolution.rs
+++ b/crates/hir_ty/src/method_resolution.rs
@@ -8,7 +8,7 @@ use arrayvec::ArrayVec;
 use base_db::{CrateId, Edition};
 use chalk_ir::{cast::Cast, Mutability, UniverseIndex};
 use hir_def::{
-    lang_item::LangItemTarget, nameres::DefMap, AssocContainerId, AssocItemId, FunctionId,
+    lang_item::LangItemTarget, nameres::DefMap, AssocContainerId, AssocItemId, BlockId, FunctionId,
     GenericDefId, HasModule, ImplId, Lookup, ModuleId, TraitId,
 };
 use hir_expand::name::Name;
@@ -60,7 +60,7 @@ impl TyFingerprint {
             TyKind::Adt(AdtId(adt), _) => TyFingerprint::Adt(*adt),
             TyKind::Raw(mutability, ..) => TyFingerprint::RawPtr(*mutability),
             TyKind::Foreign(alias_id, ..) => TyFingerprint::ForeignType(*alias_id),
-            TyKind::Dyn(_) => ty.dyn_trait().map(|trait_| TyFingerprint::Dyn(trait_))?,
+            TyKind::Dyn(_) => ty.dyn_trait().map(TyFingerprint::Dyn)?,
             _ => return None,
         };
         Some(fp)
@@ -77,7 +77,7 @@ impl TyFingerprint {
             TyKind::Adt(AdtId(adt), _) => TyFingerprint::Adt(*adt),
             TyKind::Raw(mutability, ..) => TyFingerprint::RawPtr(*mutability),
             TyKind::Foreign(alias_id, ..) => TyFingerprint::ForeignType(*alias_id),
-            TyKind::Dyn(_) => ty.dyn_trait().map(|trait_| TyFingerprint::Dyn(trait_))?,
+            TyKind::Dyn(_) => ty.dyn_trait().map(TyFingerprint::Dyn)?,
             TyKind::Ref(_, _, ty) => return TyFingerprint::for_trait_impl(ty),
             TyKind::Tuple(_, subst) => {
                 let first_ty = subst.interned().get(0).map(|arg| arg.assert_ty_ref(&Interner));
@@ -139,35 +139,47 @@ impl TraitImpls {
         let mut impls = Self { map: FxHashMap::default() };
 
         let crate_def_map = db.crate_def_map(krate);
-        collect_def_map(db, &crate_def_map, &mut impls);
+        impls.collect_def_map(db, &crate_def_map);
 
         return Arc::new(impls);
+    }
 
-        fn collect_def_map(db: &dyn HirDatabase, def_map: &DefMap, impls: &mut TraitImpls) {
-            for (_module_id, module_data) in def_map.modules() {
-                for impl_id in module_data.scope.impls() {
-                    let target_trait = match db.impl_trait(impl_id) {
-                        Some(tr) => tr.skip_binders().hir_trait_id(),
-                        None => continue,
-                    };
-                    let self_ty = db.impl_self_ty(impl_id);
-                    let self_ty_fp = TyFingerprint::for_trait_impl(self_ty.skip_binders());
-                    impls
-                        .map
-                        .entry(target_trait)
-                        .or_default()
-                        .entry(self_ty_fp)
-                        .or_default()
-                        .push(impl_id);
-                }
+    pub(crate) fn trait_impls_in_block_query(
+        db: &dyn HirDatabase,
+        block: BlockId,
+    ) -> Option<Arc<Self>> {
+        let _p = profile::span("trait_impls_in_block_query");
+        let mut impls = Self { map: FxHashMap::default() };
 
-                // To better support custom derives, collect impls in all unnamed const items.
-                // const _: () = { ... };
-                for konst in module_data.scope.unnamed_consts() {
-                    let body = db.body(konst.into());
-                    for (_, block_def_map) in body.blocks(db.upcast()) {
-                        collect_def_map(db, &block_def_map, impls);
-                    }
+        let block_def_map = db.block_def_map(block)?;
+        impls.collect_def_map(db, &block_def_map);
+
+        return Some(Arc::new(impls));
+    }
+
+    fn collect_def_map(&mut self, db: &dyn HirDatabase, def_map: &DefMap) {
+        for (_module_id, module_data) in def_map.modules() {
+            for impl_id in module_data.scope.impls() {
+                let target_trait = match db.impl_trait(impl_id) {
+                    Some(tr) => tr.skip_binders().hir_trait_id(),
+                    None => continue,
+                };
+                let self_ty = db.impl_self_ty(impl_id);
+                let self_ty_fp = TyFingerprint::for_trait_impl(self_ty.skip_binders());
+                self.map
+                    .entry(target_trait)
+                    .or_default()
+                    .entry(self_ty_fp)
+                    .or_default()
+                    .push(impl_id);
+            }
+
+            // To better support custom derives, collect impls in all unnamed const items.
+            // const _: () = { ... };
+            for konst in module_data.scope.unnamed_consts() {
+                let body = db.body(konst.into());
+                for (_, block_def_map) in body.blocks(db.upcast()) {
+                    self.collect_def_map(db, &block_def_map);
                 }
             }
         }
@@ -372,7 +384,7 @@ pub(crate) fn lookup_method(
         db,
         env,
         krate,
-        &traits_in_scope,
+        traits_in_scope,
         visible_from_module,
         Some(name),
         LookupMode::MethodCall,
@@ -484,7 +496,7 @@ fn iterate_method_candidates_impl(
         LookupMode::Path => {
             // No autoderef for path lookups
             iterate_method_candidates_for_self_ty(
-                &ty,
+                ty,
                 db,
                 env,
                 krate,
@@ -513,7 +525,7 @@ fn iterate_method_candidates_with_autoref(
         db,
         env.clone(),
         krate,
-        &traits_in_scope,
+        traits_in_scope,
         visible_from_module,
         name,
         &mut callback,
@@ -531,7 +543,7 @@ fn iterate_method_candidates_with_autoref(
         db,
         env.clone(),
         krate,
-        &traits_in_scope,
+        traits_in_scope,
         visible_from_module,
         name,
         &mut callback,
@@ -549,7 +561,7 @@ fn iterate_method_candidates_with_autoref(
         db,
         env,
         krate,
-        &traits_in_scope,
+        traits_in_scope,
         visible_from_module,
         name,
         &mut callback,
@@ -593,7 +605,7 @@ fn iterate_method_candidates_by_receiver(
             db,
             env.clone(),
             krate,
-            &traits_in_scope,
+            traits_in_scope,
             name,
             Some(receiver_ty),
             &mut callback,
@@ -870,7 +882,7 @@ fn transform_receiver_ty(
             .fill_with_unknown()
             .build(),
         AssocContainerId::ImplId(impl_id) => {
-            let impl_substs = inherent_impl_substs(db, env, impl_id, &self_ty)?;
+            let impl_substs = inherent_impl_substs(db, env, impl_id, self_ty)?;
             TyBuilder::subst_for_def(db, function_id)
                 .use_parent_substs(&impl_substs)
                 .fill_with_unknown()
diff --git a/crates/hir_ty/src/tests.rs b/crates/hir_ty/src/tests.rs
index 9d726b024..b873585c4 100644
--- a/crates/hir_ty/src/tests.rs
+++ b/crates/hir_ty/src/tests.rs
@@ -9,7 +9,7 @@ mod macros;
 mod display_source_code;
 mod incremental;
 
-use std::{env, sync::Arc};
+use std::{collections::HashMap, env, sync::Arc};
 
 use base_db::{fixture::WithFixture, FileRange, SourceDatabase, SourceDatabaseExt};
 use expect_test::Expect;
@@ -83,9 +83,105 @@ fn check_types_impl(ra_fixture: &str, display_source: bool) {
             checked_one = true;
         }
     }
+
     assert!(checked_one, "no `//^` annotations found");
 }
 
+fn check_no_mismatches(ra_fixture: &str) {
+    check_mismatches_impl(ra_fixture, true)
+}
+
+#[allow(unused)]
+fn check_mismatches(ra_fixture: &str) {
+    check_mismatches_impl(ra_fixture, false)
+}
+
+fn check_mismatches_impl(ra_fixture: &str, allow_none: bool) {
+    let _tracing = setup_tracing();
+    let (db, file_id) = TestDB::with_single_file(ra_fixture);
+    let module = db.module_for_file(file_id);
+    let def_map = module.def_map(&db);
+
+    let mut defs: Vec<DefWithBodyId> = Vec::new();
+    visit_module(&db, &def_map, module.local_id, &mut |it| defs.push(it));
+    defs.sort_by_key(|def| match def {
+        DefWithBodyId::FunctionId(it) => {
+            let loc = it.lookup(&db);
+            loc.source(&db).value.syntax().text_range().start()
+        }
+        DefWithBodyId::ConstId(it) => {
+            let loc = it.lookup(&db);
+            loc.source(&db).value.syntax().text_range().start()
+        }
+        DefWithBodyId::StaticId(it) => {
+            let loc = it.lookup(&db);
+            loc.source(&db).value.syntax().text_range().start()
+        }
+    });
+    let mut mismatches = HashMap::new();
+    let mut push_mismatch = |src_ptr: InFile<SyntaxNode>, mismatch: TypeMismatch| {
+        let range = src_ptr.value.text_range();
+        if src_ptr.file_id.call_node(&db).is_some() {
+            panic!("type mismatch in macro expansion");
+        }
+        let file_range = FileRange { file_id: src_ptr.file_id.original_file(&db), range };
+        let actual = format!(
+            "expected {}, got {}",
+            mismatch.expected.display_test(&db),
+            mismatch.actual.display_test(&db)
+        );
+        mismatches.insert(file_range, actual);
+    };
+    for def in defs {
+        let (_body, body_source_map) = db.body_with_source_map(def);
+        let inference_result = db.infer(def);
+        for (pat, mismatch) in inference_result.pat_type_mismatches() {
+            let syntax_ptr = match body_source_map.pat_syntax(pat) {
+                Ok(sp) => {
+                    let root = db.parse_or_expand(sp.file_id).unwrap();
+                    sp.map(|ptr| {
+                        ptr.either(
+                            |it| it.to_node(&root).syntax().clone(),
+                            |it| it.to_node(&root).syntax().clone(),
+                        )
+                    })
+                }
+                Err(SyntheticSyntax) => continue,
+            };
+            push_mismatch(syntax_ptr, mismatch.clone());
+        }
+        for (expr, mismatch) in inference_result.expr_type_mismatches() {
+            let node = match body_source_map.expr_syntax(expr) {
+                Ok(sp) => {
+                    let root = db.parse_or_expand(sp.file_id).unwrap();
+                    sp.map(|ptr| ptr.to_node(&root).syntax().clone())
+                }
+                Err(SyntheticSyntax) => continue,
+            };
+            push_mismatch(node, mismatch.clone());
+        }
+    }
+    let mut checked_one = false;
+    for (file_id, annotations) in db.extract_annotations() {
+        for (range, expected) in annotations {
+            let file_range = FileRange { file_id, range };
+            if let Some(mismatch) = mismatches.remove(&file_range) {
+                assert_eq!(mismatch, expected);
+            } else {
+                assert!(false, "Expected mismatch not encountered: {}\n", expected);
+            }
+            checked_one = true;
+        }
+    }
+    let mut buf = String::new();
+    for (range, mismatch) in mismatches {
+        format_to!(buf, "{:?}: {}\n", range.range, mismatch,);
+    }
+    assert!(buf.is_empty(), "Unexpected type mismatches:\n{}", buf);
+
+    assert!(checked_one || allow_none, "no `//^` annotations found");
+}
+
 fn type_at_range(db: &TestDB, pos: FileRange) -> Ty {
     let file = db.parse(pos.file_id).ok().unwrap();
     let expr = algo::find_node_at_range::<ast::Expr>(file.syntax(), pos.range).unwrap();
diff --git a/crates/hir_ty/src/tests/coercion.rs b/crates/hir_ty/src/tests/coercion.rs
index 6dac7e103..713b74165 100644
--- a/crates/hir_ty/src/tests/coercion.rs
+++ b/crates/hir_ty/src/tests/coercion.rs
@@ -1,6 +1,6 @@
 use expect_test::expect;
 
-use super::{check_infer, check_infer_with_mismatches, check_types};
+use super::{check_infer, check_infer_with_mismatches, check_no_mismatches, check_types};
 
 #[test]
 fn infer_block_expr_type_mismatch() {
@@ -23,38 +23,29 @@ fn infer_block_expr_type_mismatch() {
 fn coerce_places() {
     check_infer(
         r#"
-        struct S<T> { a: T }
+//- minicore: coerce_unsized
+struct S<T> { a: T }
 
-        fn f<T>(_: &[T]) -> T { loop {} }
-        fn g<T>(_: S<&[T]>) -> T { loop {} }
+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);
-        }
+fn gen<T>() -> *mut [T; 2] { loop {} }
+fn test1<U>() -> *mut [U] {
+    gen()
+}
 
-        #[lang = "sized"]
-        pub trait Sized {}
-        #[lang = "unsize"]
-        pub trait Unsize<T: ?Sized> {}
-        #[lang = "coerce_unsized"]
-        pub trait CoerceUnsized<T> {}
+fn test2() {
+    let arr: &[u8; 1] = &[1];
 
-        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 {}
-        "#,
+    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);
+}
+"#,
         expect![[r#"
             30..31 '_': &[T]
             44..55 '{ loop {} }': T
@@ -131,60 +122,52 @@ fn infer_let_stmt_coerce() {
 fn infer_custom_coerce_unsized() {
     check_infer(
         r#"
-        struct A<T: ?Sized>(*const T);
-        struct B<T: ?Sized>(*const T);
-        struct C<T: ?Sized> { inner: *const T }
+//- minicore: coerce_unsized
+use core::{marker::Unsize, ops::CoerceUnsized};
 
-        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> {}
+struct A<T: ?Sized>(*const T);
+struct B<T: ?Sized>(*const T);
+struct C<T: ?Sized> { inner: *const 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);
-        }
+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 }
 
-        #[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 {}
-        "#,
+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);
+}
+"#,
         expect![[r#"
-            257..258 'x': A<[T]>
-            278..283 '{ x }': A<[T]>
-            280..281 'x': A<[T]>
-            295..296 'x': B<[T]>
-            316..321 '{ x }': B<[T]>
-            318..319 'x': B<[T]>
-            333..334 'x': C<[T]>
-            354..359 '{ x }': C<[T]>
-            356..357 'x': C<[T]>
-            369..370 'a': A<[u8; 2]>
-            384..385 'b': B<[u8; 2]>
-            399..400 'c': C<[u8; 2]>
-            414..480 '{     ...(c); }': ()
-            424..425 'd': A<[{unknown}]>
-            428..432 'foo1': fn foo1<{unknown}>(A<[{unknown}]>) -> A<[{unknown}]>
-            428..435 'foo1(a)': A<[{unknown}]>
-            433..434 'a': A<[u8; 2]>
-            445..446 'e': B<[u8]>
-            449..453 'foo2': fn foo2<u8>(B<[u8]>) -> B<[u8]>
-            449..456 'foo2(b)': B<[u8]>
-            454..455 'b': B<[u8; 2]>
-            466..467 'f': C<[u8]>
-            470..474 'foo3': fn foo3<u8>(C<[u8]>) -> C<[u8]>
-            470..477 'foo3(c)': C<[u8]>
-            475..476 'c': C<[u8; 2]>
+            306..307 'x': A<[T]>
+            327..332 '{ x }': A<[T]>
+            329..330 'x': A<[T]>
+            344..345 'x': B<[T]>
+            365..370 '{ x }': B<[T]>
+            367..368 'x': B<[T]>
+            382..383 'x': C<[T]>
+            403..408 '{ x }': C<[T]>
+            405..406 'x': C<[T]>
+            418..419 'a': A<[u8; 2]>
+            433..434 'b': B<[u8; 2]>
+            448..449 'c': C<[u8; 2]>
+            463..529 '{     ...(c); }': ()
+            473..474 'd': A<[{unknown}]>
+            477..481 'foo1': fn foo1<{unknown}>(A<[{unknown}]>) -> A<[{unknown}]>
+            477..484 'foo1(a)': A<[{unknown}]>
+            482..483 'a': A<[u8; 2]>
+            494..495 'e': B<[u8]>
+            498..502 'foo2': fn foo2<u8>(B<[u8]>) -> B<[u8]>
+            498..505 'foo2(b)': B<[u8]>
+            503..504 'b': B<[u8; 2]>
+            515..516 'f': C<[u8]>
+            519..523 'foo3': fn foo3<u8>(C<[u8]>) -> C<[u8]>
+            519..526 'foo3(c)': C<[u8]>
+            524..525 'c': C<[u8; 2]>
         "#]],
     );
 }
@@ -193,21 +176,16 @@ fn infer_custom_coerce_unsized() {
 fn infer_if_coerce() {
     check_infer(
         r#"
-        fn foo<T>(x: &[T]) -> &[T] { loop {} }
-        fn test() {
-            let x = if true {
-                foo(&[1])
-            } else {
-                &[1]
-            };
-        }
-
-
-        #[lang = "sized"]
-        pub trait Sized {}
-        #[lang = "unsize"]
-        pub trait Unsize<T: ?Sized> {}
-        "#,
+//- minicore: unsize
+fn foo<T>(x: &[T]) -> &[T] { loop {} }
+fn test() {
+    let x = if true {
+        foo(&[1])
+    } else {
+        &[1]
+    };
+}
+"#,
         expect![[r#"
             10..11 'x': &[T]
             27..38 '{ loop {} }': &[T]
@@ -235,25 +213,16 @@ fn infer_if_coerce() {
 fn infer_if_else_coerce() {
     check_infer(
         r#"
-        fn foo<T>(x: &[T]) -> &[T] { loop {} }
-        fn test() {
-            let x = if true {
-                &[1]
-            } else {
-                foo(&[1])
-            };
-        }
-
-        #[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 {}
-        "#,
+//- minicore: coerce_unsized
+fn foo<T>(x: &[T]) -> &[T] { loop {} }
+fn test() {
+    let x = if true {
+        &[1]
+    } else {
+        foo(&[1])
+    };
+}
+"#,
         expect![[r#"
             10..11 'x': &[T]
             27..38 '{ loop {} }': &[T]
@@ -281,20 +250,16 @@ fn infer_if_else_coerce() {
 fn infer_match_first_coerce() {
     check_infer(
         r#"
-        fn foo<T>(x: &[T]) -> &[T] { loop {} }
-        fn test(i: i32) {
-            let x = match i {
-                2 => foo(&[2]),
-                1 => &[1],
-                _ => &[3],
-            };
-        }
-
-        #[lang = "sized"]
-        pub trait Sized {}
-        #[lang = "unsize"]
-        pub trait Unsize<T: ?Sized> {}
-        "#,
+//- minicore: unsize
+fn foo<T>(x: &[T]) -> &[T] { loop {} }
+fn test(i: i32) {
+    let x = match i {
+        2 => foo(&[2]),
+        1 => &[1],
+        _ => &[3],
+    };
+}
+"#,
         expect![[r#"
             10..11 'x': &[T]
             27..38 '{ loop {} }': &[T]
@@ -329,25 +294,16 @@ fn infer_match_first_coerce() {
 fn infer_match_second_coerce() {
     check_infer(
         r#"
-        fn foo<T>(x: &[T]) -> &[T] { loop {} }
-        fn test(i: i32) {
-            let x = match i {
-                1 => &[1],
-                2 => foo(&[2]),
-                _ => &[3],
-            };
-        }
-
-        #[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 {}
-        "#,
+//- minicore: coerce_unsized
+fn foo<T>(x: &[T]) -> &[T] { loop {} }
+fn test(i: i32) {
+    let x = match i {
+        1 => &[1],
+        2 => foo(&[2]),
+        _ => &[3],
+    };
+}
+"#,
         expect![[r#"
             10..11 'x': &[T]
             27..38 '{ loop {} }': &[T]
@@ -470,15 +426,15 @@ fn coerce_autoderef() {
 #[test]
 fn coerce_autoderef_generic() {
     check_infer_with_mismatches(
-        r"
-        struct Foo;
-        fn takes_ref<T>(x: &T) -> T { *x }
-        fn test() {
-            takes_ref(&Foo);
-            takes_ref(&&Foo);
-            takes_ref(&&&Foo);
-        }
-        ",
+        r#"
+struct Foo;
+fn takes_ref<T>(x: &T) -> T { *x }
+fn test() {
+    takes_ref(&Foo);
+    takes_ref(&&Foo);
+    takes_ref(&&&Foo);
+}
+"#,
         expect![[r"
             28..29 'x': &T
             40..46 '{ *x }': T
@@ -508,30 +464,29 @@ fn coerce_autoderef_generic() {
 fn coerce_autoderef_block() {
     check_infer_with_mismatches(
         r#"
-        struct String {}
-        #[lang = "deref"]
-        trait Deref { type Target; }
-        impl Deref for String { type Target = str; }
-        fn takes_ref_str(x: &str) {}
-        fn returns_string() -> String { loop {} }
-        fn test() {
-            takes_ref_str(&{ returns_string() });
-        }
-        "#,
-        expect![[r"
-            126..127 'x': &str
-            135..137 '{}': ()
-            168..179 '{ loop {} }': String
-            170..177 'loop {}': !
-            175..177 '{}': ()
-            190..235 '{     ... }); }': ()
-            196..209 'takes_ref_str': fn takes_ref_str(&str)
-            196..232 'takes_...g() })': ()
-            210..231 '&{ ret...ng() }': &String
-            211..231 '{ retu...ng() }': String
-            213..227 'returns_string': fn returns_string() -> String
-            213..229 'return...ring()': String
-        "]],
+//- minicore: deref
+struct String {}
+impl core::ops::Deref for String { type Target = str; }
+fn takes_ref_str(x: &str) {}
+fn returns_string() -> String { loop {} }
+fn test() {
+    takes_ref_str(&{ returns_string() });
+}
+"#,
+        expect![[r#"
+            90..91 'x': &str
+            99..101 '{}': ()
+            132..143 '{ loop {} }': String
+            134..141 'loop {}': !
+            139..141 '{}': ()
+            154..199 '{     ... }); }': ()
+            160..173 'takes_ref_str': fn takes_ref_str(&str)
+            160..196 'takes_...g() })': ()
+            174..195 '&{ ret...ng() }': &String
+            175..195 '{ retu...ng() }': String
+            177..191 'returns_string': fn returns_string() -> String
+            177..193 'return...ring()': String
+        "#]],
     );
 }
 
@@ -674,25 +629,19 @@ fn coerce_placeholder_ref() {
 fn coerce_unsize_array() {
     check_infer_with_mismatches(
         r#"
-        #[lang = "unsize"]
-        pub trait Unsize<T> {}
-        #[lang = "coerce_unsized"]
-        pub trait CoerceUnsized<T> {}
-
-        impl<T: Unsize<U>, U> CoerceUnsized<&U> for &T {}
-
-        fn test() {
-            let f: &[usize] = &[1, 2, 3];
-        }
+//- minicore: coerce_unsized
+fn test() {
+    let f: &[usize] = &[1, 2, 3];
+}
         "#,
         expect![[r#"
-            161..198 '{     ... 3]; }': ()
-            171..172 'f': &[usize]
-            185..195 '&[1, 2, 3]': &[usize; 3]
-            186..195 '[1, 2, 3]': [usize; 3]
-            187..188 '1': usize
-            190..191 '2': usize
-            193..194 '3': usize
+            10..47 '{     ... 3]; }': ()
+            20..21 'f': &[usize]
+            34..44 '&[1, 2, 3]': &[usize; 3]
+            35..44 '[1, 2, 3]': [usize; 3]
+            36..37 '1': usize
+            39..40 '2': usize
+            42..43 '3': usize
         "#]],
     );
 }
@@ -701,93 +650,94 @@ fn coerce_unsize_array() {
 fn coerce_unsize_trait_object_simple() {
     check_infer_with_mismatches(
         r#"
-        #[lang = "sized"]
-        pub trait Sized {}
-        #[lang = "unsize"]
-        pub trait Unsize<T> {}
-        #[lang = "coerce_unsized"]
-        pub trait CoerceUnsized<T> {}
-
-        impl<T: Unsize<U>, U> CoerceUnsized<&U> for &T {}
-
-        trait Foo<T, U> {}
-        trait Bar<U, T, X>: Foo<T, U> {}
-        trait Baz<T, X>: Bar<usize, T, X> {}
-
-        struct S<T, X>;
-        impl<T, X> Foo<T, usize> for S<T, X> {}
-        impl<T, X> Bar<usize, T, X> for S<T, X> {}
-        impl<T, X> Baz<T, X> for S<T, X> {}
-
-        fn test() {
-            let obj: &dyn Baz<i8, i16> = &S;
-            let obj: &dyn Bar<_, i8, i16> = &S;
-            let obj: &dyn Foo<i8, _> = &S;
-        }
-        "#,
-        expect![[r"
-            424..539 '{     ... &S; }': ()
-            434..437 'obj': &dyn Baz<i8, i16>
-            459..461 '&S': &S<i8, i16>
-            460..461 'S': S<i8, i16>
-            471..474 'obj': &dyn Bar<usize, i8, i16>
-            499..501 '&S': &S<i8, i16>
-            500..501 'S': S<i8, i16>
-            511..514 'obj': &dyn Foo<i8, usize>
-            534..536 '&S': &S<i8, {unknown}>
-            535..536 'S': S<i8, {unknown}>
-        "]],
+//- minicore: coerce_unsized
+trait Foo<T, U> {}
+trait Bar<U, T, X>: Foo<T, U> {}
+trait Baz<T, X>: Bar<usize, T, X> {}
+
+struct S<T, X>;
+impl<T, X> Foo<T, usize> for S<T, X> {}
+impl<T, X> Bar<usize, T, X> for S<T, X> {}
+impl<T, X> Baz<T, X> for S<T, X> {}
+
+fn test() {
+    let obj: &dyn Baz<i8, i16> = &S;
+    let obj: &dyn Bar<_, i8, i16> = &S;
+    let obj: &dyn Foo<i8, _> = &S;
+}
+"#,
+        expect![[r#"
+            236..351 '{     ... &S; }': ()
+            246..249 'obj': &dyn Baz<i8, i16>
+            271..273 '&S': &S<i8, i16>
+            272..273 'S': S<i8, i16>
+            283..286 'obj': &dyn Bar<usize, i8, i16>
+            311..313 '&S': &S<i8, i16>
+            312..313 'S': S<i8, i16>
+            323..326 'obj': &dyn Foo<i8, usize>
+            346..348 '&S': &S<i8, {unknown}>
+            347..348 'S': S<i8, {unknown}>
+        "#]],
     );
 }
 
 #[test]
-// The rust reference says this should be possible, but rustc doesn't implement
-// it. We used to support it, but Chalk doesn't.
-#[ignore]
 fn coerce_unsize_trait_object_to_trait_object() {
+    // FIXME: The rust reference says this should be possible, but rustc doesn't
+    // implement it. We used to support it, but Chalk doesn't. Here's the
+    // correct expect:
+    //
+    //     424..609 '{     ...bj2; }': ()
+    //     434..437 'obj': &dyn Baz<i8, i16>
+    //     459..461 '&S': &S<i8, i16>
+    //     460..461 'S': S<i8, i16>
+    //     471..474 'obj': &dyn Bar<usize, i8, i16>
+    //     496..499 'obj': &dyn Baz<i8, i16>
+    //     509..512 'obj': &dyn Foo<i8, usize>
+    //     531..534 'obj': &dyn Bar<usize, i8, i16>
+    //     544..548 'obj2': &dyn Baz<i8, i16>
+    //     570..572 '&S': &S<i8, i16>
+    //     571..572 'S': S<i8, i16>
+    //     582..583 '_': &dyn Foo<i8, usize>
+    //     602..606 'obj2': &dyn Baz<i8, i16>
     check_infer_with_mismatches(
         r#"
-        #[lang = "sized"]
-        pub trait Sized {}
-        #[lang = "unsize"]
-        pub trait Unsize<T> {}
-        #[lang = "coerce_unsized"]
-        pub trait CoerceUnsized<T> {}
-
-        impl<T: Unsize<U>, U> CoerceUnsized<&U> for &T {}
-
-        trait Foo<T, U> {}
-        trait Bar<U, T, X>: Foo<T, U> {}
-        trait Baz<T, X>: Bar<usize, T, X> {}
-
-        struct S<T, X>;
-        impl<T, X> Foo<T, usize> for S<T, X> {}
-        impl<T, X> Bar<usize, T, X> for S<T, X> {}
-        impl<T, X> Baz<T, X> for S<T, X> {}
-
-        fn test() {
-            let obj: &dyn Baz<i8, i16> = &S;
-            let obj: &dyn Bar<_, _, _> = obj;
-            let obj: &dyn Foo<_, _> = obj;
-            let obj2: &dyn Baz<i8, i16> = &S;
-            let _: &dyn Foo<_, _> = obj2;
-        }
-        "#,
-        expect![[r"
-            424..609 '{     ...bj2; }': ()
-            434..437 'obj': &dyn Baz<i8, i16>
-            459..461 '&S': &S<i8, i16>
-            460..461 'S': S<i8, i16>
-            471..474 'obj': &dyn Bar<usize, i8, i16>
-            496..499 'obj': &dyn Baz<i8, i16>
-            509..512 'obj': &dyn Foo<i8, usize>
-            531..534 'obj': &dyn Bar<usize, i8, i16>
-            544..548 'obj2': &dyn Baz<i8, i16>
-            570..572 '&S': &S<i8, i16>
-            571..572 'S': S<i8, i16>
-            582..583 '_': &dyn Foo<i8, usize>
-            602..606 'obj2': &dyn Baz<i8, i16>
-        "]],
+//- minicore: coerce_unsized
+trait Foo<T, U> {}
+trait Bar<U, T, X>: Foo<T, U> {}
+trait Baz<T, X>: Bar<usize, T, X> {}
+
+struct S<T, X>;
+impl<T, X> Foo<T, usize> for S<T, X> {}
+impl<T, X> Bar<usize, T, X> for S<T, X> {}
+impl<T, X> Baz<T, X> for S<T, X> {}
+
+fn test() {
+    let obj: &dyn Baz<i8, i16> = &S;
+    let obj: &dyn Bar<_, _, _> = obj;
+    let obj: &dyn Foo<_, _> = obj;
+    let obj2: &dyn Baz<i8, i16> = &S;
+    let _: &dyn Foo<_, _> = obj2;
+}
+"#,
+        expect![[r#"
+            236..421 '{     ...bj2; }': ()
+            246..249 'obj': &dyn Baz<i8, i16>
+            271..273 '&S': &S<i8, i16>
+            272..273 'S': S<i8, i16>
+            283..286 'obj': &dyn Bar<{unknown}, {unknown}, {unknown}>
+            308..311 'obj': &dyn Baz<i8, i16>
+            321..324 'obj': &dyn Foo<{unknown}, {unknown}>
+            343..346 'obj': &dyn Bar<{unknown}, {unknown}, {unknown}>
+            356..360 'obj2': &dyn Baz<i8, i16>
+            382..384 '&S': &S<i8, i16>
+            383..384 'S': S<i8, i16>
+            394..395 '_': &dyn Foo<{unknown}, {unknown}>
+            414..418 'obj2': &dyn Baz<i8, i16>
+            308..311: expected &dyn Bar<{unknown}, {unknown}, {unknown}>, got &dyn Baz<i8, i16>
+            343..346: expected &dyn Foo<{unknown}, {unknown}>, got &dyn Bar<{unknown}, {unknown}, {unknown}>
+            414..418: expected &dyn Foo<{unknown}, {unknown}>, got &dyn Baz<i8, i16>
+        "#]],
     );
 }
 
@@ -795,40 +745,32 @@ fn coerce_unsize_trait_object_to_trait_object() {
 fn coerce_unsize_super_trait_cycle() {
     check_infer_with_mismatches(
         r#"
-        #[lang = "sized"]
-        pub trait Sized {}
-        #[lang = "unsize"]
-        pub trait Unsize<T> {}
-        #[lang = "coerce_unsized"]
-        pub trait CoerceUnsized<T> {}
-
-        impl<T: Unsize<U>, U> CoerceUnsized<&U> for &T {}
-
-        trait A {}
-        trait B: C + A {}
-        trait C: B {}
-        trait D: C
-
-        struct S;
-        impl A for S {}
-        impl B for S {}
-        impl C for S {}
-        impl D for S {}
-
-        fn test() {
-            let obj: &dyn D = &S;
-            let obj: &dyn A = &S;
-        }
-        "#,
-        expect![[r"
-            328..383 '{     ... &S; }': ()
-            338..341 'obj': &dyn D
-            352..354 '&S': &S
-            353..354 'S': S
-            364..367 'obj': &dyn A
-            378..380 '&S': &S
-            379..380 'S': S
-        "]],
+//- minicore: coerce_unsized
+trait A {}
+trait B: C + A {}
+trait C: B {}
+trait D: C
+
+struct S;
+impl A for S {}
+impl B for S {}
+impl C for S {}
+impl D for S {}
+
+fn test() {
+    let obj: &dyn D = &S;
+    let obj: &dyn A = &S;
+}
+"#,
+        expect![[r#"
+            140..195 '{     ... &S; }': ()
+            150..153 'obj': &dyn D
+            164..166 '&S': &S
+            165..166 'S': S
+            176..179 'obj': &dyn A
+            190..192 '&S': &S
+            191..192 'S': S
+        "#]],
     );
 }
 
@@ -837,41 +779,35 @@ fn coerce_unsize_generic() {
     // FIXME: fix the type mismatches here
     check_infer_with_mismatches(
         r#"
-        #[lang = "unsize"]
-        pub trait Unsize<T> {}
-        #[lang = "coerce_unsized"]
-        pub trait CoerceUnsized<T> {}
-
-        impl<T: Unsize<U>, U> CoerceUnsized<&U> for &T {}
+//- minicore: coerce_unsized
+struct Foo<T> { t: T };
+struct Bar<T>(Foo<T>);
 
-        struct Foo<T> { t: T };
-        struct Bar<T>(Foo<T>);
-
-        fn test() {
-            let _: &Foo<[usize]> = &Foo { t: [1, 2, 3] };
-            let _: &Bar<[usize]> = &Bar(Foo { t: [1, 2, 3] });
-        }
-        "#,
+fn test() {
+    let _: &Foo<[usize]> = &Foo { t: [1, 2, 3] };
+    let _: &Bar<[usize]> = &Bar(Foo { t: [1, 2, 3] });
+}
+"#,
         expect![[r#"
-            209..317 '{     ... }); }': ()
-            219..220 '_': &Foo<[usize]>
-            238..259 '&Foo {..., 3] }': &Foo<[usize]>
-            239..259 'Foo { ..., 3] }': Foo<[usize]>
-            248..257 '[1, 2, 3]': [usize; 3]
-            249..250 '1': usize
-            252..253 '2': usize
-            255..256 '3': usize
-            269..270 '_': &Bar<[usize]>
-            288..314 '&Bar(F... 3] })': &Bar<[i32; 3]>
-            289..292 'Bar': Bar<[i32; 3]>(Foo<[i32; 3]>) -> Bar<[i32; 3]>
-            289..314 'Bar(Fo... 3] })': Bar<[i32; 3]>
-            293..313 'Foo { ..., 3] }': Foo<[i32; 3]>
-            302..311 '[1, 2, 3]': [i32; 3]
-            303..304 '1': i32
-            306..307 '2': i32
-            309..310 '3': i32
-            248..257: expected [usize], got [usize; 3]
-            288..314: expected &Bar<[usize]>, got &Bar<[i32; 3]>
+            58..166 '{     ... }); }': ()
+            68..69 '_': &Foo<[usize]>
+            87..108 '&Foo {..., 3] }': &Foo<[usize]>
+            88..108 'Foo { ..., 3] }': Foo<[usize]>
+            97..106 '[1, 2, 3]': [usize; 3]
+            98..99 '1': usize
+            101..102 '2': usize
+            104..105 '3': usize
+            118..119 '_': &Bar<[usize]>
+            137..163 '&Bar(F... 3] })': &Bar<[i32; 3]>
+            138..141 'Bar': Bar<[i32; 3]>(Foo<[i32; 3]>) -> Bar<[i32; 3]>
+            138..163 'Bar(Fo... 3] })': Bar<[i32; 3]>
+            142..162 'Foo { ..., 3] }': Foo<[i32; 3]>
+            151..160 '[1, 2, 3]': [i32; 3]
+            152..153 '1': i32
+            155..156 '2': i32
+            158..159 '3': i32
+            97..106: expected [usize], got [usize; 3]
+            137..163: expected &Bar<[usize]>, got &Bar<[i32; 3]>
         "#]],
     );
 }
@@ -881,15 +817,7 @@ fn coerce_unsize_apit() {
     // FIXME: #8984
     check_infer_with_mismatches(
         r#"
-#[lang = "sized"]
-pub trait Sized {}
-#[lang = "unsize"]
-pub trait Unsize<T> {}
-#[lang = "coerce_unsized"]
-pub trait CoerceUnsized<T> {}
-
-impl<T: Unsize<U>, U> CoerceUnsized<&U> for &T {}
-
+//- minicore: coerce_unsized
 trait Foo {}
 
 fn test(f: impl Foo) {
@@ -897,12 +825,12 @@ fn test(f: impl Foo) {
 }
         "#,
         expect![[r#"
-            210..211 'f': impl Foo
-            223..252 '{     ... &f; }': ()
-            233..234 '_': &dyn Foo
-            247..249 '&f': &impl Foo
-            248..249 'f': impl Foo
-            247..249: expected &dyn Foo, got &impl Foo
+            22..23 'f': impl Foo
+            35..64 '{     ... &f; }': ()
+            45..46 '_': &dyn Foo
+            59..61 '&f': &impl Foo
+            60..61 'f': impl Foo
+            59..61: expected &dyn Foo, got &impl Foo
         "#]],
     );
 }
@@ -963,7 +891,7 @@ fn test() -> i32 {
 
 #[test]
 fn panic_macro() {
-    check_infer_with_mismatches(
+    check_no_mismatches(
         r#"
 mod panic {
     #[macro_export]
@@ -991,15 +919,26 @@ fn main() {
     panic!()
 }
         "#,
-        expect![[r#"
-            174..185 '{ loop {} }': !
-            176..183 'loop {}': !
-            181..183 '{}': ()
-            !0..24 '$crate...:panic': fn panic() -> !
-            !0..26 '$crate...anic()': !
-            !0..26 '$crate...anic()': !
-            !0..28 '$crate...015!()': !
-            454..470 '{     ...c!() }': ()
-        "#]],
+    );
+}
+
+#[test]
+fn coerce_unsize_expected_type() {
+    check_no_mismatches(
+        r#"
+//- minicore: coerce_unsized
+fn main() {
+    let foo: &[u32] = &[1, 2];
+    let foo: &[u32] = match true {
+        true => &[1, 2],
+        false => &[1, 2, 3],
+    };
+    let foo: &[u32] = if true {
+        &[1, 2]
+    } else {
+        &[1, 2, 3]
+    };
+}
+        "#,
     );
 }
diff --git a/crates/hir_ty/src/tests/method_resolution.rs b/crates/hir_ty/src/tests/method_resolution.rs
index f26b2c8a7..d9b5ee9cf 100644
--- a/crates/hir_ty/src/tests/method_resolution.rs
+++ b/crates/hir_ty/src/tests/method_resolution.rs
@@ -780,10 +780,7 @@ fn test() { (&S).foo(); }
 fn method_resolution_unsize_array() {
     check_types(
         r#"
-#[lang = "slice"]
-impl<T> [T] {
-    fn len(&self) -> usize { loop {} }
-}
+//- minicore: slice
 fn test() {
     let a = [1, 2, 3];
     a.len();
@@ -1178,11 +1175,7 @@ fn main() {
 fn autoderef_visibility_field() {
     check_infer(
         r#"
-#[lang = "deref"]
-pub trait Deref {
-    type Target;
-    fn deref(&self) -> &Self::Target;
-}
+//- minicore: deref
 mod a {
     pub struct Foo(pub char);
     pub struct Bar(i32);
@@ -1191,7 +1184,7 @@ mod a {
             Self(0)
         }
     }
-    impl super::Deref for Bar {
+    impl core::ops::Deref for Bar {
         type Target = Foo;
         fn deref(&self) -> &Foo {
             &Foo('z')
@@ -1205,22 +1198,21 @@ mod b {
 }
         "#,
         expect![[r#"
-            67..71 'self': &Self
-            200..231 '{     ...     }': Bar
-            214..218 'Self': Bar(i32) -> Bar
-            214..221 'Self(0)': Bar
-            219..220 '0': i32
-            315..319 'self': &Bar
-            329..362 '{     ...     }': &Foo
-            343..352 '&Foo('z')': &Foo
-            344..347 'Foo': Foo(char) -> Foo
-            344..352 'Foo('z')': Foo
-            348..351 ''z'': char
-            392..439 '{     ...     }': ()
-            406..407 'x': char
-            410..428 'super:...r::new': fn new() -> Bar
-            410..430 'super:...:new()': Bar
-            410..432 'super:...ew().0': char
+            107..138 '{     ...     }': Bar
+            121..125 'Self': Bar(i32) -> Bar
+            121..128 'Self(0)': Bar
+            126..127 '0': i32
+            226..230 'self': &Bar
+            240..273 '{     ...     }': &Foo
+            254..263 '&Foo('z')': &Foo
+            255..258 'Foo': Foo(char) -> Foo
+            255..263 'Foo('z')': Foo
+            259..262 ''z'': char
+            303..350 '{     ...     }': ()
+            317..318 'x': char
+            321..339 'super:...r::new': fn new() -> Bar
+            321..341 'super:...:new()': Bar
+            321..343 'super:...ew().0': char
         "#]],
     )
 }
@@ -1230,11 +1222,7 @@ fn autoderef_visibility_method() {
     cov_mark::check!(autoderef_candidate_not_visible);
     check_infer(
         r#"
-#[lang = "deref"]
-pub trait Deref {
-    type Target;
-    fn deref(&self) -> &Self::Target;
-}
+//- minicore: deref
 mod a {
     pub struct Foo(pub char);
     impl Foo {
@@ -1251,7 +1239,7 @@ mod a {
             self.0
         }
     }
-    impl super::Deref for Bar {
+    impl core::ops::Deref for Bar {
         type Target = Foo;
         fn deref(&self) -> &Foo {
             &Foo('z')
@@ -1265,30 +1253,29 @@ mod b {
 }
         "#,
         expect![[r#"
-            67..71 'self': &Self
-            168..172 'self': &Foo
-            182..212 '{     ...     }': char
-            196..200 'self': &Foo
-            196..202 'self.0': char
-            288..319 '{     ...     }': Bar
-            302..306 'Self': Bar(i32) -> Bar
-            302..309 'Self(0)': Bar
-            307..308 '0': i32
-            338..342 'self': &Bar
-            351..381 '{     ...     }': i32
-            365..369 'self': &Bar
-            365..371 'self.0': i32
-            465..469 'self': &Bar
-            479..512 '{     ...     }': &Foo
-            493..502 '&Foo('z')': &Foo
-            494..497 'Foo': Foo(char) -> Foo
-            494..502 'Foo('z')': Foo
-            498..501 ''z'': char
-            542..595 '{     ...     }': ()
-            556..557 'x': char
-            560..578 'super:...r::new': fn new() -> Bar
-            560..580 'super:...:new()': Bar
-            560..588 'super:...ango()': char
+            75..79 'self': &Foo
+            89..119 '{     ...     }': char
+            103..107 'self': &Foo
+            103..109 'self.0': char
+            195..226 '{     ...     }': Bar
+            209..213 'Self': Bar(i32) -> Bar
+            209..216 'Self(0)': Bar
+            214..215 '0': i32
+            245..249 'self': &Bar
+            258..288 '{     ...     }': i32
+            272..276 'self': &Bar
+            272..278 'self.0': i32
+            376..380 'self': &Bar
+            390..423 '{     ...     }': &Foo
+            404..413 '&Foo('z')': &Foo
+            405..408 'Foo': Foo(char) -> Foo
+            405..413 'Foo('z')': Foo
+            409..412 ''z'': char
+            453..506 '{     ...     }': ()
+            467..468 'x': char
+            471..489 'super:...r::new': fn new() -> Bar
+            471..491 'super:...:new()': Bar
+            471..499 'super:...ango()': char
         "#]],
     )
 }
diff --git a/crates/hir_ty/src/tests/patterns.rs b/crates/hir_ty/src/tests/patterns.rs
index 7d00cee9b..5adbe9c45 100644
--- a/crates/hir_ty/src/tests/patterns.rs
+++ b/crates/hir_ty/src/tests/patterns.rs
@@ -1,6 +1,6 @@
 use expect_test::expect;
 
-use super::{check_infer, check_infer_with_mismatches, check_types};
+use super::{check_infer, check_infer_with_mismatches, check_mismatches, check_types};
 
 #[test]
 fn infer_pattern() {
@@ -518,47 +518,24 @@ fn infer_generics_in_patterns() {
 
 #[test]
 fn infer_const_pattern() {
-    check_infer_with_mismatches(
+    check_mismatches(
         r#"
-        enum Option<T> { None }
-        use Option::None;
-        struct Foo;
-        const Bar: usize = 1;
-
-        fn test() {
-            let a: Option<u32> = None;
-            let b: Option<i64> = match a {
-                None => None,
-            };
-            let _: () = match () { Foo => Foo }; // Expected mismatch
-            let _: () = match () { Bar => Bar }; // Expected mismatch
-        }
+enum Option<T> { None }
+use Option::None;
+struct Foo;
+const Bar: usize = 1;
+
+fn test() {
+    let a: Option<u32> = None;
+    let b: Option<i64> = match a {
+        None => None,
+    };
+    let _: () = match () { Foo => () };
+                        // ^^^ expected (), got Foo
+    let _: () = match () { Bar => () };
+                        // ^^^ expected (), got usize
+}
         "#,
-        expect![[r#"
-            73..74 '1': usize
-            87..309 '{     ...atch }': ()
-            97..98 'a': Option<u32>
-            114..118 'None': Option<u32>
-            128..129 'b': Option<i64>
-            145..182 'match ...     }': Option<i64>
-            151..152 'a': Option<u32>
-            163..167 'None': Option<u32>
-            171..175 'None': Option<i64>
-            192..193 '_': ()
-            200..223 'match ... Foo }': Foo
-            206..208 '()': ()
-            211..214 'Foo': Foo
-            218..221 'Foo': Foo
-            254..255 '_': ()
-            262..285 'match ... Bar }': usize
-            268..270 '()': ()
-            273..276 'Bar': usize
-            280..283 'Bar': usize
-            200..223: expected (), got Foo
-            211..214: expected (), got Foo
-            262..285: expected (), got usize
-            273..276: expected (), got usize
-        "#]],
     );
 }
 
@@ -594,48 +571,44 @@ fn main() {
 fn match_ergonomics_in_closure_params() {
     check_infer(
         r#"
-        #[lang = "fn_once"]
-        trait FnOnce<Args> {
-            type Output;
-        }
-
-        fn foo<T, U, F: FnOnce(T) -> U>(t: T, f: F) -> U { loop {} }
+//- minicore: fn
+fn foo<T, U, F: FnOnce(T) -> U>(t: T, f: F) -> U { loop {} }
 
-        fn test() {
-            foo(&(1, "a"), |&(x, y)| x); // normal, no match ergonomics
-            foo(&(1, "a"), |(x, y)| x);
-        }
-        "#,
+fn test() {
+    foo(&(1, "a"), |&(x, y)| x); // normal, no match ergonomics
+    foo(&(1, "a"), |(x, y)| x);
+}
+"#,
         expect![[r#"
-            93..94 't': T
-            99..100 'f': F
-            110..121 '{ loop {} }': U
-            112..119 'loop {}': !
-            117..119 '{}': ()
-            133..232 '{     ... x); }': ()
-            139..142 'foo': fn foo<&(i32, &str), i32, |&(i32, &str)| -> i32>(&(i32, &str), |&(i32, &str)| -> i32) -> i32
-            139..166 'foo(&(...y)| x)': i32
-            143..152 '&(1, "a")': &(i32, &str)
-            144..152 '(1, "a")': (i32, &str)
-            145..146 '1': i32
-            148..151 '"a"': &str
-            154..165 '|&(x, y)| x': |&(i32, &str)| -> i32
-            155..162 '&(x, y)': &(i32, &str)
-            156..162 '(x, y)': (i32, &str)
-            157..158 'x': i32
-            160..161 'y': &str
-            164..165 'x': i32
-            203..206 'foo': fn foo<&(i32, &str), &i32, |&(i32, &str)| -> &i32>(&(i32, &str), |&(i32, &str)| -> &i32) -> &i32
-            203..229 'foo(&(...y)| x)': &i32
-            207..216 '&(1, "a")': &(i32, &str)
-            208..216 '(1, "a")': (i32, &str)
-            209..210 '1': i32
-            212..215 '"a"': &str
-            218..228 '|(x, y)| x': |&(i32, &str)| -> &i32
-            219..225 '(x, y)': (i32, &str)
-            220..221 'x': &i32
-            223..224 'y': &&str
-            227..228 'x': &i32
+            32..33 't': T
+            38..39 'f': F
+            49..60 '{ loop {} }': U
+            51..58 'loop {}': !
+            56..58 '{}': ()
+            72..171 '{     ... x); }': ()
+            78..81 'foo': fn foo<&(i32, &str), i32, |&(i32, &str)| -> i32>(&(i32, &str), |&(i32, &str)| -> i32) -> i32
+            78..105 'foo(&(...y)| x)': i32
+            82..91 '&(1, "a")': &(i32, &str)
+            83..91 '(1, "a")': (i32, &str)
+            84..85 '1': i32
+            87..90 '"a"': &str
+            93..104 '|&(x, y)| x': |&(i32, &str)| -> i32
+            94..101 '&(x, y)': &(i32, &str)
+            95..101 '(x, y)': (i32, &str)
+            96..97 'x': i32
+            99..100 'y': &str
+            103..104 'x': i32
+            142..145 'foo': fn foo<&(i32, &str), &i32, |&(i32, &str)| -> &i32>(&(i32, &str), |&(i32, &str)| -> &i32) -> &i32
+            142..168 'foo(&(...y)| x)': &i32
+            146..155 '&(1, "a")': &(i32, &str)
+            147..155 '(1, "a")': (i32, &str)
+            148..149 '1': i32
+            151..154 '"a"': &str
+            157..167 '|(x, y)| x': |&(i32, &str)| -> &i32
+            158..164 '(x, y)': (i32, &str)
+            159..160 'x': &i32
+            162..163 'y': &&str
+            166..167 'x': &i32
         "#]],
     );
 }
diff --git a/crates/hir_ty/src/tests/regression.rs b/crates/hir_ty/src/tests/regression.rs
index 1019e783b..1edec1615 100644
--- a/crates/hir_ty/src/tests/regression.rs
+++ b/crates/hir_ty/src/tests/regression.rs
@@ -884,41 +884,37 @@ fn issue_4966() {
 fn issue_6628() {
     check_infer(
         r#"
-        #[lang = "fn_once"]
-        pub trait FnOnce<Args> {
-            type Output;
-        }
-
-        struct S<T>();
-        impl<T> S<T> {
-            fn f(&self, _t: T) {}
-            fn g<F: FnOnce(&T)>(&self, _f: F) {}
-        }
-        fn main() {
-            let s = S();
-            s.g(|_x| {});
-            s.f(10);
-        }
-        "#,
+//- minicore: fn
+struct S<T>();
+impl<T> S<T> {
+    fn f(&self, _t: T) {}
+    fn g<F: FnOnce(&T)>(&self, _f: F) {}
+}
+fn main() {
+    let s = S();
+    s.g(|_x| {});
+    s.f(10);
+}
+"#,
         expect![[r#"
-            105..109 'self': &S<T>
-            111..113 '_t': T
-            118..120 '{}': ()
-            146..150 'self': &S<T>
-            152..154 '_f': F
-            159..161 '{}': ()
-            174..225 '{     ...10); }': ()
-            184..185 's': S<i32>
-            188..189 'S': S<i32>() -> S<i32>
-            188..191 'S()': S<i32>
-            197..198 's': S<i32>
-            197..209 's.g(|_x| {})': ()
-            201..208 '|_x| {}': |&i32| -> ()
-            202..204 '_x': &i32
-            206..208 '{}': ()
-            215..216 's': S<i32>
-            215..222 's.f(10)': ()
-            219..221 '10': i32
+            40..44 'self': &S<T>
+            46..48 '_t': T
+            53..55 '{}': ()
+            81..85 'self': &S<T>
+            87..89 '_f': F
+            94..96 '{}': ()
+            109..160 '{     ...10); }': ()
+            119..120 's': S<i32>
+            123..124 'S': S<i32>() -> S<i32>
+            123..126 'S()': S<i32>
+            132..133 's': S<i32>
+            132..144 's.g(|_x| {})': ()
+            136..143 '|_x| {}': |&i32| -> ()
+            137..139 '_x': &i32
+            141..143 '{}': ()
+            150..151 's': S<i32>
+            150..157 's.f(10)': ()
+            154..156 '10': i32
         "#]],
     );
 }
@@ -927,35 +923,33 @@ fn issue_6628() {
 fn issue_6852() {
     check_infer(
         r#"
-        #[lang = "deref"]
-        pub trait Deref {
-            type Target;
-        }
+//- minicore: deref
+use core::ops::Deref;
 
-        struct BufWriter {}
+struct BufWriter {}
 
-        struct Mutex<T> {}
-        struct MutexGuard<'a, T> {}
-        impl<T> Mutex<T> {
-            fn lock(&self) -> MutexGuard<'_, T> {}
-        }
-        impl<'a, T: 'a> Deref for MutexGuard<'a, T> {
-            type Target = T;
-        }
-        fn flush(&self) {
-            let w: &Mutex<BufWriter>;
-            *(w.lock());
-        }
-        "#,
+struct Mutex<T> {}
+struct MutexGuard<'a, T> {}
+impl<T> Mutex<T> {
+    fn lock(&self) -> MutexGuard<'_, T> {}
+}
+impl<'a, T: 'a> Deref for MutexGuard<'a, T> {
+    type Target = T;
+}
+fn flush(&self) {
+    let w: &Mutex<BufWriter>;
+    *(w.lock());
+}
+"#,
         expect![[r#"
-            156..160 'self': &Mutex<T>
-            183..185 '{}': ()
-            267..271 'self': &{unknown}
-            273..323 '{     ...()); }': ()
-            283..284 'w': &Mutex<BufWriter>
-            309..320 '*(w.lock())': BufWriter
-            311..312 'w': &Mutex<BufWriter>
-            311..319 'w.lock()': MutexGuard<BufWriter>
+            123..127 'self': &Mutex<T>
+            150..152 '{}': ()
+            234..238 'self': &{unknown}
+            240..290 '{     ...()); }': ()
+            250..251 'w': &Mutex<BufWriter>
+            276..287 '*(w.lock())': BufWriter
+            278..279 'w': &Mutex<BufWriter>
+            278..286 'w.lock()': MutexGuard<BufWriter>
         "#]],
     );
 }
@@ -977,37 +971,33 @@ fn param_overrides_fn() {
 fn lifetime_from_chalk_during_deref() {
     check_types(
         r#"
-        #[lang = "deref"]
-        pub trait Deref {
-            type Target;
-        }
-
-        struct Box<T: ?Sized> {}
-        impl<T> Deref for Box<T> {
-            type Target = T;
+//- minicore: deref
+struct Box<T: ?Sized> {}
+impl<T> core::ops::Deref for Box<T> {
+    type Target = T;
 
-            fn deref(&self) -> &Self::Target {
-                loop {}
-            }
-        }
+    fn deref(&self) -> &Self::Target {
+        loop {}
+    }
+}
 
-        trait Iterator {
-            type Item;
-        }
+trait Iterator {
+    type Item;
+}
 
-        pub struct Iter<'a, T: 'a> {
-            inner: Box<dyn IterTrait<'a, T, Item = &'a T> + 'a>,
-        }
+pub struct Iter<'a, T: 'a> {
+    inner: Box<dyn IterTrait<'a, T, Item = &'a T> + 'a>,
+}
 
-        trait IterTrait<'a, T: 'a>: Iterator<Item = &'a T> {
-            fn clone_box(&self);
-        }
+trait IterTrait<'a, T: 'a>: Iterator<Item = &'a T> {
+    fn clone_box(&self);
+}
 
-        fn clone_iter<T>(s: Iter<T>) {
-            s.inner.clone_box();
-          //^^^^^^^^^^^^^^^^^^^ ()
-        }
-        "#,
+fn clone_iter<T>(s: Iter<T>) {
+    s.inner.clone_box();
+    //^^^^^^^^^^^^^^^^^^^ ()
+}
+"#,
     )
 }
 
diff --git a/crates/hir_ty/src/tests/simple.rs b/crates/hir_ty/src/tests/simple.rs
index 3418ed21e..68776f3c0 100644
--- a/crates/hir_ty/src/tests/simple.rs
+++ b/crates/hir_ty/src/tests/simple.rs
@@ -113,7 +113,7 @@ fn type_alias_in_struct_lit() {
 fn infer_ranges() {
     check_types(
         r#"
-//- /main.rs crate:main deps:core
+//- minicore: range
 fn test() {
     let a = ..;
     let b = 1..;
@@ -125,32 +125,6 @@ fn test() {
     let t = (a, b, c, d, e, f);
     t;
 } //^ (RangeFull, RangeFrom<i32>, RangeTo<u32>, Range<usize>, RangeToInclusive<i32>, RangeInclusive<char>)
-
-//- /core.rs crate:core
-#[prelude_import] use prelude::*;
-mod prelude {}
-
-pub mod ops {
-    pub struct Range<Idx> {
-        pub start: Idx,
-        pub end: Idx,
-    }
-    pub struct RangeFrom<Idx> {
-        pub start: Idx,
-    }
-    struct RangeFull;
-    pub struct RangeInclusive<Idx> {
-        start: Idx,
-        end: Idx,
-        is_empty: u8,
-    }
-    pub struct RangeTo<Idx> {
-        pub end: Idx,
-    }
-    pub struct RangeToInclusive<Idx> {
-        pub end: Idx,
-    }
-}
 "#,
     );
 }
@@ -175,16 +149,17 @@ fn test() {
 fn infer_basics() {
     check_infer(
         r#"
-        fn test(a: u32, b: isize, c: !, d: &str) {
-            a;
-            b;
-            c;
-            d;
-            1usize;
-            1isize;
-            "test";
-            1.0f32;
-        }"#,
+fn test(a: u32, b: isize, c: !, d: &str) {
+    a;
+    b;
+    c;
+    d;
+    1usize;
+    1isize;
+    "test";
+    1.0f32;
+}
+"#,
         expect![[r#"
             8..9 'a': u32
             16..17 'b': isize
@@ -207,15 +182,15 @@ fn infer_basics() {
 fn infer_let() {
     check_infer(
         r#"
-        fn test() {
-            let a = 1isize;
-            let b: usize = 1;
-            let c = b;
-            let d: u32;
-            let e;
-            let f: i32 = e;
-        }
-        "#,
+fn test() {
+    let a = 1isize;
+    let b: usize = 1;
+    let c = b;
+    let d: u32;
+    let e;
+    let f: i32 = e;
+}
+"#,
         expect![[r#"
             10..117 '{     ...= e; }': ()
             20..21 'a': isize
@@ -236,17 +211,17 @@ fn infer_let() {
 fn infer_paths() {
     check_infer(
         r#"
-        fn a() -> u32 { 1 }
+fn a() -> u32 { 1 }
 
-        mod b {
-            fn c() -> u32 { 1 }
-        }
+mod b {
+    fn c() -> u32 { 1 }
+}
 
-        fn test() {
-            a();
-            b::c();
-        }
-        "#,
+fn test() {
+    a();
+    b::c();
+}
+"#,
         expect![[r#"
             14..19 '{ 1 }': u32
             16..17 '1': u32
@@ -265,17 +240,17 @@ fn infer_paths() {
 fn infer_path_type() {
     check_infer(
         r#"
-        struct S;
+struct S;
 
-        impl S {
-            fn foo() -> i32 { 1 }
-        }
+impl S {
+    fn foo() -> i32 { 1 }
+}
 
-        fn test() {
-            S::foo();
-            <S>::foo();
-        }
-        "#,
+fn test() {
+    S::foo();
+    <S>::foo();
+}
+"#,
         expect![[r#"
             40..45 '{ 1 }': i32
             42..43 '1': i32
@@ -292,21 +267,21 @@ fn infer_path_type() {
 fn infer_struct() {
     check_infer(
         r#"
-        struct A {
-            b: B,
-            c: C,
-        }
-        struct B;
-        struct C(usize);
+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;
-        }
-        "#,
+fn test() {
+    let c = C(1);
+    B;
+    let a: A = A { b: B, c: C(1) };
+    a.b;
+    a.c;
+}
+"#,
         expect![[r#"
             71..153 '{     ...a.c; }': ()
             81..82 'c': C
@@ -332,14 +307,15 @@ fn infer_struct() {
 fn infer_enum() {
     check_infer(
         r#"
-        enum E {
-            V1 { field: u32 },
-            V2
-        }
-        fn test() {
-            E::V1 { field: 1 };
-            E::V2;
-        }"#,
+enum E {
+    V1 { field: u32 },
+    V2
+}
+fn test() {
+    E::V1 { field: 1 };
+    E::V2;
+}
+"#,
         expect![[r#"
             51..89 '{     ...:V2; }': ()
             57..75 'E::V1 ...d: 1 }': E
@@ -353,23 +329,23 @@ fn infer_enum() {
 fn infer_union() {
     check_infer(
         r#"
-        union MyUnion {
-            foo: u32,
-            bar: f32,
-        }
+union MyUnion {
+    foo: u32,
+    bar: f32,
+}
 
-        fn test() {
-            let u = MyUnion { foo: 0 };
-            unsafe { baz(u); }
-            let u = MyUnion { bar: 0.0 };
-            unsafe { baz(u); }
-        }
+fn test() {
+    let u = MyUnion { foo: 0 };
+    unsafe { baz(u); }
+    let u = MyUnion { bar: 0.0 };
+    unsafe { baz(u); }
+}
 
-        unsafe fn baz(u: MyUnion) {
-            let inner = u.foo;
-            let inner = u.bar;
-        }
-        "#,
+unsafe fn baz(u: MyUnion) {
+    let inner = u.foo;
+    let inner = u.bar;
+}
+"#,
         expect![[r#"
             57..172 '{     ...); } }': ()
             67..68 'u': MyUnion
@@ -404,19 +380,19 @@ fn infer_union() {
 fn infer_refs() {
     check_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;
-        }
+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;
+}
         "#,
         expect![[r#"
             8..9 'a': &u32
@@ -450,11 +426,11 @@ fn infer_refs() {
 fn infer_raw_ref() {
     check_infer(
         r#"
-        fn test(a: i32) {
-            &raw mut a;
-            &raw const a;
-        }
-        "#,
+fn test(a: i32) {
+    &raw mut a;
+    &raw const a;
+}
+"#,
         expect![[r#"
             8..9 'a': i32
             16..53 '{     ...t a; }': ()
@@ -524,26 +500,26 @@ h";
 fn infer_unary_op() {
     check_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";
-        }
-        "#,
+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";
+}
+"#,
         expect![[r#"
             26..27 'x': SomeType
             39..271 '{     ...lo"; }': ()
@@ -594,19 +570,19 @@ fn infer_unary_op() {
 fn infer_backwards() {
     check_infer(
         r#"
-        fn takes_u32(x: u32) {}
+fn takes_u32(x: u32) {}
 
-        struct S { i32_field: i32 }
+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
-        }
-        "#,
+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
+}
+"#,
         expect![[r#"
             13..14 'x': u32
             21..23 '{}': ()
@@ -636,23 +612,23 @@ fn infer_backwards() {
 fn infer_self() {
     check_infer(
         r#"
-        struct S;
+struct S;
 
-        impl S {
-            fn test(&self) {
-                self;
-            }
-            fn test2(self: &Self) {
-                self;
-            }
-            fn test3() -> Self {
-                S {}
-            }
-            fn test4() -> Self {
-                Self {}
-            }
-        }
-        "#,
+impl S {
+    fn test(&self) {
+        self;
+    }
+    fn test2(self: &Self) {
+        self;
+    }
+    fn test3() -> Self {
+        S {}
+    }
+    fn test4() -> Self {
+        Self {}
+    }
+}
+"#,
         expect![[r#"
             33..37 'self': &S
             39..60 '{     ...     }': ()
@@ -672,30 +648,30 @@ fn infer_self() {
 fn infer_self_as_path() {
     check_infer(
         r#"
-        struct S1;
-        struct S2(isize);
-        enum E {
-            V1,
-            V2(u32),
-        }
+struct S1;
+struct S2(isize);
+enum E {
+    V1,
+    V2(u32),
+}
 
-        impl S1 {
-            fn test() {
-                Self;
-            }
-        }
-        impl S2 {
-            fn test() {
-                Self(1);
-            }
-        }
-        impl E {
-            fn test() {
-                Self::V1;
-                Self::V2(1);
-            }
-        }
-        "#,
+impl S1 {
+    fn test() {
+        Self;
+    }
+}
+impl S2 {
+    fn test() {
+        Self(1);
+    }
+}
+impl E {
+    fn test() {
+        Self::V1;
+        Self::V2(1);
+    }
+}
+"#,
         expect![[r#"
             86..107 '{     ...     }': ()
             96..100 'Self': S1
@@ -716,26 +692,26 @@ fn infer_self_as_path() {
 fn infer_binary_op() {
     check_infer(
         r#"
-        fn f(x: bool) -> i32 {
-            0i32
-        }
+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
-        }
-        "#,
+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
+}
+"#,
         expect![[r#"
             5..6 'x': bool
             21..33 '{     0i32 }': i32
@@ -795,11 +771,11 @@ fn infer_binary_op() {
 fn infer_shift_op() {
     check_infer(
         r#"
-        fn test() {
-            1u32 << 5u8;
-            1u32 >> 5u8;
-        }
-        "#,
+fn test() {
+    1u32 << 5u8;
+    1u32 >> 5u8;
+}
+"#,
         expect![[r#"
             10..47 '{     ...5u8; }': ()
             16..20 '1u32': u32
@@ -816,29 +792,29 @@ fn infer_shift_op() {
 fn infer_field_autoderef() {
     check_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;
-        }
+struct A {
+    b: B,
+}
+struct B;
 
-        fn test2(a1: *const A, a2: *mut A) {
-            a1.b;
-            a2.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;
+}
+"#,
         expect![[r#"
             43..44 'a': A
             49..212 '{     ...5.b; }': ()
@@ -891,58 +867,53 @@ fn infer_field_autoderef() {
 fn infer_argument_autoderef() {
     check_infer(
         r#"
-        #[lang = "deref"]
-        pub trait Deref {
-            type Target;
-            fn deref(&self) -> &Self::Target;
-        }
-
-        struct A<T>(T);
+//- minicore: deref
+use core::ops::Deref;
+struct A<T>(T);
 
-        impl<T> A<T> {
-            fn foo(&self) -> &T {
-                &self.0
-            }
-        }
+impl<T> A<T> {
+    fn foo(&self) -> &T {
+        &self.0
+    }
+}
 
-        struct B<T>(T);
+struct B<T>(T);
 
-        impl<T> Deref for B<T> {
-            type Target = T;
-            fn deref(&self) -> &Self::Target {
-                &self.0
-            }
-        }
+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))));
-        }
-        "#,
+fn test() {
+    let t = A::foo(&&B(B(A(42))));
+}
+"#,
         expect![[r#"
-            67..71 'self': &Self
-            138..142 'self': &A<T>
-            150..173 '{     ...     }': &T
-            160..167 '&self.0': &T
-            161..165 'self': &A<T>
-            161..167 'self.0': T
-            254..258 'self': &B<T>
-            277..300 '{     ...     }': &T
-            287..294 '&self.0': &T
-            288..292 'self': &B<T>
-            288..294 'self.0': T
-            314..352 '{     ...))); }': ()
-            324..325 't': &i32
-            328..334 'A::foo': fn foo<i32>(&A<i32>) -> &i32
-            328..349 'A::foo...42))))': &i32
-            335..348 '&&B(B(A(42)))': &&B<B<A<i32>>>
-            336..348 '&B(B(A(42)))': &B<B<A<i32>>>
-            337..338 'B': B<B<A<i32>>>(B<A<i32>>) -> B<B<A<i32>>>
-            337..348 'B(B(A(42)))': B<B<A<i32>>>
-            339..340 'B': B<A<i32>>(A<i32>) -> B<A<i32>>
-            339..347 'B(A(42))': B<A<i32>>
-            341..342 'A': A<i32>(i32) -> A<i32>
-            341..346 'A(42)': A<i32>
-            343..345 '42': i32
+            66..70 'self': &A<T>
+            78..101 '{     ...     }': &T
+            88..95 '&self.0': &T
+            89..93 'self': &A<T>
+            89..95 'self.0': T
+            182..186 'self': &B<T>
+            205..228 '{     ...     }': &T
+            215..222 '&self.0': &T
+            216..220 'self': &B<T>
+            216..222 'self.0': T
+            242..280 '{     ...))); }': ()
+            252..253 't': &i32
+            256..262 'A::foo': fn foo<i32>(&A<i32>) -> &i32
+            256..277 'A::foo...42))))': &i32
+            263..276 '&&B(B(A(42)))': &&B<B<A<i32>>>
+            264..276 '&B(B(A(42)))': &B<B<A<i32>>>
+            265..266 'B': B<B<A<i32>>>(B<A<i32>>) -> B<B<A<i32>>>
+            265..276 'B(B(A(42)))': B<B<A<i32>>>
+            267..268 'B': B<A<i32>>(A<i32>) -> B<A<i32>>
+            267..275 'B(A(42))': B<A<i32>>
+            269..270 'A': A<i32>(i32) -> A<i32>
+            269..274 'A(42)': A<i32>
+            271..273 '42': i32
         "#]],
     );
 }
@@ -951,62 +922,57 @@ fn infer_argument_autoderef() {
 fn infer_method_argument_autoderef() {
     check_infer(
         r#"
-        #[lang = "deref"]
-        pub trait Deref {
-            type Target;
-            fn deref(&self) -> &Self::Target;
-        }
+//- minicore: deref
+use core::ops::Deref;
+struct A<T>(*mut T);
 
-        struct A<T>(*mut T);
-
-        impl<T> A<T> {
-            fn foo(&self, x: &A<T>) -> &T {
-                &*x.0
-            }
-        }
+impl<T> A<T> {
+    fn foo(&self, x: &A<T>) -> &T {
+        &*x.0
+    }
+}
 
-        struct B<T>(T);
+struct B<T>(T);
 
-        impl<T> Deref for B<T> {
-            type Target = T;
-            fn deref(&self) -> &Self::Target {
-                &self.0
-            }
-        }
+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)));
-        }
-        "#,
+fn test(a: A<i32>) {
+    let t = A(0 as *mut _).foo(&&B(B(a)));
+}
+"#,
         expect![[r#"
-            67..71 'self': &Self
-            143..147 'self': &A<T>
-            149..150 'x': &A<T>
-            165..186 '{     ...     }': &T
-            175..180 '&*x.0': &T
-            176..180 '*x.0': T
-            177..178 'x': &A<T>
-            177..180 'x.0': *mut T
-            267..271 'self': &B<T>
-            290..313 '{     ...     }': &T
-            300..307 '&self.0': &T
-            301..305 'self': &B<T>
-            301..307 'self.0': T
-            325..326 'a': A<i32>
-            336..382 '{     ...))); }': ()
-            346..347 't': &i32
-            350..351 'A': A<i32>(*mut i32) -> A<i32>
-            350..364 'A(0 as *mut _)': A<i32>
-            350..379 'A(0 as...B(a)))': &i32
-            352..353 '0': i32
-            352..363 '0 as *mut _': *mut i32
-            369..378 '&&B(B(a))': &&B<B<A<i32>>>
-            370..378 '&B(B(a))': &B<B<A<i32>>>
-            371..372 'B': B<B<A<i32>>>(B<A<i32>>) -> B<B<A<i32>>>
-            371..378 'B(B(a))': B<B<A<i32>>>
-            373..374 'B': B<A<i32>>(A<i32>) -> B<A<i32>>
-            373..377 'B(a)': B<A<i32>>
-            375..376 'a': A<i32>
+            71..75 'self': &A<T>
+            77..78 'x': &A<T>
+            93..114 '{     ...     }': &T
+            103..108 '&*x.0': &T
+            104..108 '*x.0': T
+            105..106 'x': &A<T>
+            105..108 'x.0': *mut T
+            195..199 'self': &B<T>
+            218..241 '{     ...     }': &T
+            228..235 '&self.0': &T
+            229..233 'self': &B<T>
+            229..235 'self.0': T
+            253..254 'a': A<i32>
+            264..310 '{     ...))); }': ()
+            274..275 't': &i32
+            278..279 'A': A<i32>(*mut i32) -> A<i32>
+            278..292 'A(0 as *mut _)': A<i32>
+            278..307 'A(0 as...B(a)))': &i32
+            280..281 '0': i32
+            280..291 '0 as *mut _': *mut i32
+            297..306 '&&B(B(a))': &&B<B<A<i32>>>
+            298..306 '&B(B(a))': &B<B<A<i32>>>
+            299..300 'B': B<B<A<i32>>>(B<A<i32>>) -> B<B<A<i32>>>
+            299..306 'B(B(a))': B<B<A<i32>>>
+            301..302 'B': B<A<i32>>(A<i32>) -> B<A<i32>>
+            301..305 'B(a)': B<A<i32>>
+            303..304 'a': A<i32>
         "#]],
     );
 }
@@ -1015,15 +981,15 @@ fn infer_method_argument_autoderef() {
 fn infer_in_elseif() {
     check_infer(
         r#"
-        struct Foo { field: i32 }
-        fn main(foo: Foo) {
-            if true {
+struct Foo { field: i32 }
+fn main(foo: Foo) {
+    if true {
 
-            } else if false {
-                foo.field
-            }
-        }
-        "#,
+    } else if false {
+        foo.field
+    }
+}
+"#,
         expect![[r#"
             34..37 'foo': Foo
             44..108 '{     ...   } }': ()
@@ -1043,28 +1009,29 @@ fn infer_in_elseif() {
 fn infer_if_match_with_return() {
     check_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
-            };
-        }"#,
+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
+    };
+}
+"#,
         expect![[r#"
             9..322 '{     ...  }; }': ()
             19..22 '_x1': i32
@@ -2639,11 +2606,8 @@ fn f() {
 fn infer_boxed_self_receiver() {
     check_infer(
         r#"
-#[lang = "deref"]
-pub trait Deref {
-    type Target;
-    fn deref(&self) -> &Self::Target;
-}
+//- minicore: deref
+use core::ops::Deref;
 
 struct Box<T>(T);
 
@@ -2675,40 +2639,39 @@ fn main() {
 }
         "#,
         expect![[r#"
-            67..71 'self': &Self
-            175..179 'self': &Box<T>
-            259..263 'self': &Box<Foo<T>>
-            289..291 '{}': ()
-            313..317 'self': &Box<Foo<T>>
-            346..348 '{}': ()
-            368..372 'self': Box<Foo<T>>
-            393..395 '{}': ()
-            409..630 '{     ...r(); }': ()
-            419..424 'boxed': Box<Foo<i32>>
-            427..430 'Box': Box<Foo<i32>>(Foo<i32>) -> Box<Foo<i32>>
-            427..442 'Box(Foo(0_i32))': Box<Foo<i32>>
-            431..434 'Foo': Foo<i32>(i32) -> Foo<i32>
-            431..441 'Foo(0_i32)': Foo<i32>
-            435..440 '0_i32': i32
-            453..457 'bad1': &i32
-            460..465 'boxed': Box<Foo<i32>>
-            460..477 'boxed....nner()': &i32
-            487..492 'good1': &i32
-            495..509 'Foo::get_inner': fn get_inner<i32>(&Box<Foo<i32>>) -> &i32
-            495..517 'Foo::g...boxed)': &i32
-            510..516 '&boxed': &Box<Foo<i32>>
-            511..516 'boxed': Box<Foo<i32>>
-            528..532 'bad2': &Foo<i32>
-            535..540 'boxed': Box<Foo<i32>>
-            535..551 'boxed....self()': &Foo<i32>
-            561..566 'good2': &Foo<i32>
-            569..582 'Foo::get_self': fn get_self<i32>(&Box<Foo<i32>>) -> &Foo<i32>
-            569..590 'Foo::g...boxed)': &Foo<i32>
-            583..589 '&boxed': &Box<Foo<i32>>
-            584..589 'boxed': Box<Foo<i32>>
-            601..606 'inner': Foo<i32>
-            609..614 'boxed': Box<Foo<i32>>
-            609..627 'boxed....nner()': Foo<i32>
+            104..108 'self': &Box<T>
+            188..192 'self': &Box<Foo<T>>
+            218..220 '{}': ()
+            242..246 'self': &Box<Foo<T>>
+            275..277 '{}': ()
+            297..301 'self': Box<Foo<T>>
+            322..324 '{}': ()
+            338..559 '{     ...r(); }': ()
+            348..353 'boxed': Box<Foo<i32>>
+            356..359 'Box': Box<Foo<i32>>(Foo<i32>) -> Box<Foo<i32>>
+            356..371 'Box(Foo(0_i32))': Box<Foo<i32>>
+            360..363 'Foo': Foo<i32>(i32) -> Foo<i32>
+            360..370 'Foo(0_i32)': Foo<i32>
+            364..369 '0_i32': i32
+            382..386 'bad1': &i32
+            389..394 'boxed': Box<Foo<i32>>
+            389..406 'boxed....nner()': &i32
+            416..421 'good1': &i32
+            424..438 'Foo::get_inner': fn get_inner<i32>(&Box<Foo<i32>>) -> &i32
+            424..446 'Foo::g...boxed)': &i32
+            439..445 '&boxed': &Box<Foo<i32>>
+            440..445 'boxed': Box<Foo<i32>>
+            457..461 'bad2': &Foo<i32>
+            464..469 'boxed': Box<Foo<i32>>
+            464..480 'boxed....self()': &Foo<i32>
+            490..495 'good2': &Foo<i32>
+            498..511 'Foo::get_self': fn get_self<i32>(&Box<Foo<i32>>) -> &Foo<i32>
+            498..519 'Foo::g...boxed)': &Foo<i32>
+            512..518 '&boxed': &Box<Foo<i32>>
+            513..518 'boxed': Box<Foo<i32>>
+            530..535 'inner': Foo<i32>
+            538..543 'boxed': Box<Foo<i32>>
+            538..556 'boxed....nner()': Foo<i32>
         "#]],
     );
 }
diff --git a/crates/hir_ty/src/tests/traits.rs b/crates/hir_ty/src/tests/traits.rs
index 588f0d1d4..065cca74f 100644
--- a/crates/hir_ty/src/tests/traits.rs
+++ b/crates/hir_ty/src/tests/traits.rs
@@ -6,10 +6,10 @@ use super::{check_infer, check_infer_with_mismatches, check_types};
 fn infer_await() {
     check_types(
         r#"
-//- /main.rs crate:main deps:core
+//- minicore: future
 struct IntFuture;
 
-impl Future for IntFuture {
+impl core::future::Future for IntFuture {
     type Output = u64;
 }
 
@@ -18,16 +18,6 @@ fn test() {
     let v = r.await;
     v;
 } //^ u64
-
-//- /core.rs crate:core
-pub mod prelude {
-    pub mod rust_2018 {
-        #[lang = "future_trait"]
-        pub trait Future {
-            type Output;
-        }
-    }
-}
 "#,
     );
 }
@@ -36,25 +26,14 @@ pub mod prelude {
 fn infer_async() {
     check_types(
         r#"
-//- /main.rs crate:main deps:core
-async fn foo() -> u64 {
-            128
-}
+//- minicore: future
+async fn foo() -> u64 { 128 }
 
 fn test() {
     let r = foo();
     let v = r.await;
     v;
 } //^ u64
-
-//- /core.rs crate:core
-#[prelude_import] use future::*;
-mod future {
-    #[lang = "future_trait"]
-    trait Future {
-        type Output;
-    }
-}
 "#,
     );
 }
@@ -63,24 +42,13 @@ mod future {
 fn infer_desugar_async() {
     check_types(
         r#"
-//- /main.rs crate:main deps:core
-async fn foo() -> u64 {
-            128
-}
+//- minicore: future
+async fn foo() -> u64 { 128 }
 
 fn test() {
     let r = foo();
     r;
 } //^ impl Future<Output = u64>
-
-//- /core.rs crate:core
-#[prelude_import] use future::*;
-mod future {
-    trait Future {
-        type Output;
-    }
-}
-
 "#,
     );
 }
@@ -89,7 +57,7 @@ mod future {
 fn infer_async_block() {
     check_types(
         r#"
-//- /main.rs crate:main deps:core
+//- minicore: future, option
 async fn test() {
     let a = async { 42 };
     a;
@@ -101,7 +69,7 @@ async fn test() {
     b;
 //  ^ ()
     let c = async {
-        let y = Option::None;
+        let y = None;
         y
     //  ^ Option<u64>
     };
@@ -109,18 +77,6 @@ async fn test() {
     c;
 //  ^ impl Future<Output = Option<u64>>
 }
-
-enum Option<T> { None, Some(T) }
-
-//- /core.rs crate:core
-#[prelude_import] use future::*;
-mod future {
-    #[lang = "future_trait"]
-    trait Future {
-        type Output;
-    }
-}
-
 "#,
     );
 }
@@ -704,14 +660,9 @@ mod ops {
 fn deref_trait() {
     check_types(
         r#"
-#[lang = "deref"]
-trait Deref {
-    type Target;
-    fn deref(&self) -> &Self::Target;
-}
-
+//- minicore: deref
 struct Arc<T>;
-impl<T> Deref for Arc<T> {
+impl<T> core::ops::Deref for Arc<T> {
     type Target = T;
 }
 
@@ -731,16 +682,10 @@ fn test(s: Arc<S>) {
 fn deref_trait_with_inference_var() {
     check_types(
         r#"
-//- /main.rs
-#[lang = "deref"]
-trait Deref {
-    type Target;
-    fn deref(&self) -> &Self::Target;
-}
-
+//- minicore: deref
 struct Arc<T>;
 fn new_arc<T>() -> Arc<T> {}
-impl<T> Deref for Arc<T> {
+impl<T> core::ops::Deref for Arc<T> {
     type Target = T;
 }
 
@@ -761,15 +706,10 @@ fn test() {
 fn deref_trait_infinite_recursion() {
     check_types(
         r#"
-#[lang = "deref"]
-trait Deref {
-    type Target;
-    fn deref(&self) -> &Self::Target;
-}
-
+//- minicore: deref
 struct S;
 
-impl Deref for S {
+impl core::ops::Deref for S {
     type Target = S;
 }
 
@@ -784,14 +724,9 @@ fn test(s: S) {
 fn deref_trait_with_question_mark_size() {
     check_types(
         r#"
-#[lang = "deref"]
-trait Deref {
-    type Target;
-    fn deref(&self) -> &Self::Target;
-}
-
+//- minicore: deref
 struct Arc<T>;
-impl<T> Deref for Arc<T> {
+impl<T: ?Sized> core::ops::Deref for Arc<T> {
     type Target = T;
 }
 
@@ -1475,7 +1410,6 @@ fn test(
 }
 
 #[test]
-#[ignore]
 fn error_bound_chalk() {
     check_types(
         r#"
@@ -1912,11 +1846,7 @@ fn test() {
 fn closure_1() {
     check_infer_with_mismatches(
         r#"
-#[lang = "fn_once"]
-trait FnOnce<Args> {
-    type Output;
-}
-
+//- minicore: fn
 enum Option<T> { Some(T), None }
 impl<T> Option<T> {
     fn map<U, F: FnOnce(T) -> U>(self, f: F) -> Option<U> { loop {} }
@@ -1929,34 +1859,34 @@ fn test() {
     let y: Option<i64> = x.map(|_v| 1);
 }"#,
         expect![[r#"
-            147..151 'self': Option<T>
-            153..154 'f': F
-            172..183 '{ loop {} }': Option<U>
-            174..181 'loop {}': !
-            179..181 '{}': ()
-            197..316 '{     ... 1); }': ()
-            207..208 'x': Option<u32>
-            211..223 'Option::Some': Some<u32>(u32) -> Option<u32>
-            211..229 'Option...(1u32)': Option<u32>
-            224..228 '1u32': u32
-            235..236 'x': Option<u32>
-            235..251 'x.map(...v + 1)': Option<u32>
-            241..250 '|v| v + 1': |u32| -> u32
-            242..243 'v': u32
-            245..246 'v': u32
-            245..250 'v + 1': u32
-            249..250 '1': u32
-            257..258 'x': Option<u32>
-            257..273 'x.map(... 1u64)': Option<u64>
-            263..272 '|_v| 1u64': |u32| -> u64
-            264..266 '_v': u32
-            268..272 '1u64': u64
-            283..284 'y': Option<i64>
-            300..301 'x': Option<u32>
-            300..313 'x.map(|_v| 1)': Option<i64>
-            306..312 '|_v| 1': |u32| -> i64
-            307..309 '_v': u32
-            311..312 '1': i64
+            86..90 'self': Option<T>
+            92..93 'f': F
+            111..122 '{ loop {} }': Option<U>
+            113..120 'loop {}': !
+            118..120 '{}': ()
+            136..255 '{     ... 1); }': ()
+            146..147 'x': Option<u32>
+            150..162 'Option::Some': Some<u32>(u32) -> Option<u32>
+            150..168 'Option...(1u32)': Option<u32>
+            163..167 '1u32': u32
+            174..175 'x': Option<u32>
+            174..190 'x.map(...v + 1)': Option<u32>
+            180..189 '|v| v + 1': |u32| -> u32
+            181..182 'v': u32
+            184..185 'v': u32
+            184..189 'v + 1': u32
+            188..189 '1': u32
+            196..197 'x': Option<u32>
+            196..212 'x.map(... 1u64)': Option<u64>
+            202..211 '|_v| 1u64': |u32| -> u64
+            203..205 '_v': u32
+            207..211 '1u64': u64
+            222..223 'y': Option<i64>
+            239..240 'x': Option<u32>
+            239..252 'x.map(|_v| 1)': Option<i64>
+            245..251 '|_v| 1': |u32| -> i64
+            246..248 '_v': u32
+            250..251 '1': i64
         "#]],
     );
 }
@@ -2030,11 +1960,7 @@ fn test<F: FnOnce(u32) -> u64>(f: F) {
 fn closure_as_argument_inference_order() {
     check_infer_with_mismatches(
         r#"
-#[lang = "fn_once"]
-trait FnOnce<Args> {
-    type Output;
-}
-
+//- minicore: fn
 fn foo1<T, U, F: FnOnce(T) -> U>(x: T, f: F) -> U { loop {} }
 fn foo2<T, U, F: FnOnce(T) -> U>(f: F, x: T) -> U { loop {} }
 
@@ -2053,62 +1979,62 @@ fn test() {
     let x4 = S.foo2(|s| s.method(), S);
 }"#,
         expect![[r#"
-            94..95 'x': T
-            100..101 'f': F
-            111..122 '{ loop {} }': U
-            113..120 'loop {}': !
-            118..120 '{}': ()
-            156..157 'f': F
-            162..163 'x': T
-            173..184 '{ loop {} }': U
-            175..182 'loop {}': !
-            180..182 '{}': ()
-            219..223 'self': S
-            271..275 'self': S
-            277..278 'x': T
-            283..284 'f': F
-            294..305 '{ loop {} }': U
-            296..303 'loop {}': !
-            301..303 '{}': ()
-            343..347 'self': S
-            349..350 'f': F
-            355..356 'x': T
-            366..377 '{ loop {} }': U
-            368..375 'loop {}': !
-            373..375 '{}': ()
-            391..550 '{     ... S); }': ()
-            401..403 'x1': u64
-            406..410 'foo1': fn foo1<S, u64, |S| -> u64>(S, |S| -> u64) -> u64
-            406..429 'foo1(S...hod())': u64
-            411..412 'S': S
-            414..428 '|s| s.method()': |S| -> u64
-            415..416 's': S
-            418..419 's': S
-            418..428 's.method()': u64
-            439..441 'x2': u64
-            444..448 'foo2': fn foo2<S, u64, |S| -> u64>(|S| -> u64, S) -> u64
-            444..467 'foo2(|...(), S)': u64
-            449..463 '|s| s.method()': |S| -> u64
-            450..451 's': S
-            453..454 's': S
-            453..463 's.method()': u64
-            465..466 'S': S
-            477..479 'x3': u64
-            482..483 'S': S
-            482..507 'S.foo1...hod())': u64
-            489..490 'S': S
-            492..506 '|s| s.method()': |S| -> u64
-            493..494 's': S
-            496..497 's': S
-            496..506 's.method()': u64
-            517..519 'x4': u64
-            522..523 'S': S
-            522..547 'S.foo2...(), S)': u64
-            529..543 '|s| s.method()': |S| -> u64
-            530..531 's': S
-            533..534 's': S
-            533..543 's.method()': u64
-            545..546 'S': S
+            33..34 'x': T
+            39..40 'f': F
+            50..61 '{ loop {} }': U
+            52..59 'loop {}': !
+            57..59 '{}': ()
+            95..96 'f': F
+            101..102 'x': T
+            112..123 '{ loop {} }': U
+            114..121 'loop {}': !
+            119..121 '{}': ()
+            158..162 'self': S
+            210..214 'self': S
+            216..217 'x': T
+            222..223 'f': F
+            233..244 '{ loop {} }': U
+            235..242 'loop {}': !
+            240..242 '{}': ()
+            282..286 'self': S
+            288..289 'f': F
+            294..295 'x': T
+            305..316 '{ loop {} }': U
+            307..314 'loop {}': !
+            312..314 '{}': ()
+            330..489 '{     ... S); }': ()
+            340..342 'x1': u64
+            345..349 'foo1': fn foo1<S, u64, |S| -> u64>(S, |S| -> u64) -> u64
+            345..368 'foo1(S...hod())': u64
+            350..351 'S': S
+            353..367 '|s| s.method()': |S| -> u64
+            354..355 's': S
+            357..358 's': S
+            357..367 's.method()': u64
+            378..380 'x2': u64
+            383..387 'foo2': fn foo2<S, u64, |S| -> u64>(|S| -> u64, S) -> u64
+            383..406 'foo2(|...(), S)': u64
+            388..402 '|s| s.method()': |S| -> u64
+            389..390 's': S
+            392..393 's': S
+            392..402 's.method()': u64
+            404..405 'S': S
+            416..418 'x3': u64
+            421..422 'S': S
+            421..446 'S.foo1...hod())': u64
+            428..429 'S': S
+            431..445 '|s| s.method()': |S| -> u64
+            432..433 's': S
+            435..436 's': S
+            435..445 's.method()': u64
+            456..458 'x4': u64
+            461..462 'S': S
+            461..486 'S.foo2...(), S)': u64
+            468..482 '|s| s.method()': |S| -> u64
+            469..470 's': S
+            472..473 's': S
+            472..482 's.method()': u64
+            484..485 'S': S
         "#]],
     );
 }
@@ -2117,11 +2043,7 @@ fn test() {
 fn fn_item_fn_trait() {
     check_types(
         r#"
-#[lang = "fn_once"]
-trait FnOnce<Args> {
-    type Output;
-}
-
+//- minicore: fn
 struct S;
 
 fn foo() -> S {}
@@ -2560,12 +2482,7 @@ fn test() -> impl Trait<i32> {
 fn assoc_types_from_bounds() {
     check_infer(
         r#"
-//- /main.rs
-#[lang = "fn_once"]
-trait FnOnce<Args> {
-    type Output;
-}
-
+//- minicore: fn
 trait T {
     type O;
 }
@@ -2584,15 +2501,15 @@ fn main() {
     f::<(), _>(|z| { z; });
 }"#,
         expect![[r#"
-            133..135 '_v': F
-            178..181 '{ }': ()
-            193..224 '{     ... }); }': ()
-            199..209 'f::<(), _>': fn f<(), |&()| -> ()>(|&()| -> ())
-            199..221 'f::<()... z; })': ()
-            210..220 '|z| { z; }': |&()| -> ()
-            211..212 'z': &()
-            214..220 '{ z; }': ()
-            216..217 'z': &()
+            72..74 '_v': F
+            117..120 '{ }': ()
+            132..163 '{     ... }); }': ()
+            138..148 'f::<(), _>': fn f<(), |&()| -> ()>(|&()| -> ())
+            138..160 'f::<()... z; })': ()
+            149..159 '|z| { z; }': |&()| -> ()
+            150..151 'z': &()
+            153..159 '{ z; }': ()
+            155..156 'z': &()
         "#]],
     );
 }
@@ -2626,12 +2543,9 @@ fn test<T: Trait>() {
 fn dyn_trait_through_chalk() {
     check_types(
         r#"
+//- minicore: deref
 struct Box<T> {}
-#[lang = "deref"]
-trait Deref {
-    type Target;
-}
-impl<T> Deref for Box<T> {
+impl<T> core::ops::Deref for Box<T> {
     type Target = T;
 }
 trait Trait {
@@ -2668,17 +2582,7 @@ fn test() {
 fn iterator_chain() {
     check_infer_with_mismatches(
         r#"
-//- /main.rs
-#[lang = "fn_once"]
-trait FnOnce<Args> {
-    type Output;
-}
-#[lang = "fn_mut"]
-trait FnMut<Args>: FnOnce<Args> { }
-
-enum Option<T> { Some(T), None }
-use Option::*;
-
+//- minicore: fn, option
 pub trait Iterator {
     type Item;
 
@@ -2738,46 +2642,46 @@ fn main() {
     .for_each(|y| { y; });
 }"#,
         expect![[r#"
-            226..230 'self': Self
-            232..233 'f': F
-            317..328 '{ loop {} }': FilterMap<Self, F>
-            319..326 'loop {}': !
-            324..326 '{}': ()
-            349..353 'self': Self
-            355..356 'f': F
-            405..416 '{ loop {} }': ()
-            407..414 'loop {}': !
-            412..414 '{}': ()
-            525..529 'self': Self
-            854..858 'self': I
-            865..885 '{     ...     }': I
-            875..879 'self': I
-            944..955 '{ loop {} }': Vec<T>
-            946..953 'loop {}': !
-            951..953 '{}': ()
-            1142..1269 '{     ... }); }': ()
-            1148..1163 'Vec::<i32>::new': fn new<i32>() -> Vec<i32>
-            1148..1165 'Vec::<...:new()': Vec<i32>
-            1148..1177 'Vec::<...iter()': IntoIter<i32>
-            1148..1240 'Vec::<...one })': FilterMap<IntoIter<i32>, |i32| -> Option<u32>>
-            1148..1266 'Vec::<... y; })': ()
-            1194..1239 '|x| if...None }': |i32| -> Option<u32>
-            1195..1196 'x': i32
-            1198..1239 'if x >...None }': Option<u32>
-            1201..1202 'x': i32
-            1201..1206 'x > 0': bool
-            1205..1206 '0': i32
-            1207..1225 '{ Some...u32) }': Option<u32>
-            1209..1213 'Some': Some<u32>(u32) -> Option<u32>
-            1209..1223 'Some(x as u32)': Option<u32>
-            1214..1215 'x': i32
-            1214..1222 'x as u32': u32
-            1231..1239 '{ None }': Option<u32>
-            1233..1237 'None': Option<u32>
-            1255..1265 '|y| { y; }': |u32| -> ()
-            1256..1257 'y': u32
-            1259..1265 '{ y; }': ()
-            1261..1262 'y': u32
+            61..65 'self': Self
+            67..68 'f': F
+            152..163 '{ loop {} }': FilterMap<Self, F>
+            154..161 'loop {}': !
+            159..161 '{}': ()
+            184..188 'self': Self
+            190..191 'f': F
+            240..251 '{ loop {} }': ()
+            242..249 'loop {}': !
+            247..249 '{}': ()
+            360..364 'self': Self
+            689..693 'self': I
+            700..720 '{     ...     }': I
+            710..714 'self': I
+            779..790 '{ loop {} }': Vec<T>
+            781..788 'loop {}': !
+            786..788 '{}': ()
+            977..1104 '{     ... }); }': ()
+            983..998 'Vec::<i32>::new': fn new<i32>() -> Vec<i32>
+            983..1000 'Vec::<...:new()': Vec<i32>
+            983..1012 'Vec::<...iter()': IntoIter<i32>
+            983..1075 'Vec::<...one })': FilterMap<IntoIter<i32>, |i32| -> Option<u32>>
+            983..1101 'Vec::<... y; })': ()
+            1029..1074 '|x| if...None }': |i32| -> Option<u32>
+            1030..1031 'x': i32
+            1033..1074 'if x >...None }': Option<u32>
+            1036..1037 'x': i32
+            1036..1041 'x > 0': bool
+            1040..1041 '0': i32
+            1042..1060 '{ Some...u32) }': Option<u32>
+            1044..1048 'Some': Some<u32>(u32) -> Option<u32>
+            1044..1058 'Some(x as u32)': Option<u32>
+            1049..1050 'x': i32
+            1049..1057 'x as u32': u32
+            1066..1074 '{ None }': Option<u32>
+            1068..1072 'None': Option<u32>
+            1090..1100 '|y| { y; }': |u32| -> ()
+            1091..1092 'y': u32
+            1094..1100 '{ y; }': ()
+            1096..1097 'y': u32
         "#]],
     );
 }
@@ -3064,45 +2968,23 @@ fn foo() {
 fn infer_fn_trait_arg() {
     check_infer_with_mismatches(
         r#"
-        //- /lib.rs deps:std
-
-        #[lang = "fn_once"]
-        pub trait FnOnce<Args> {
-            type Output;
-
-            extern "rust-call" fn call_once(&self, args: Args) -> Self::Output;
-        }
-
-        #[lang = "fn"]
-        pub trait Fn<Args>:FnOnce<Args> {
-            extern "rust-call" fn call(&self, args: Args) -> Self::Output;
-        }
-
-        enum Option<T> {
-            None,
-            Some(T)
-        }
-
-        fn foo<F, T>(f: F) -> T
-        where
-            F: Fn(Option<i32>) -> T,
-        {
-            let s = None;
-            f(s)
-        }
-        "#,
+//- minicore: fn, option
+fn foo<F, T>(f: F) -> T
+where
+    F: Fn(Option<i32>) -> T,
+{
+    let s = None;
+    f(s)
+}
+"#,
         expect![[r#"
-            101..105 'self': &Self
-            107..111 'args': Args
-            220..224 'self': &Self
-            226..230 'args': Args
-            313..314 'f': F
-            359..389 '{     ...f(s) }': T
-            369..370 's': Option<i32>
-            373..377 'None': Option<i32>
-            383..384 'f': F
-            383..387 'f(s)': T
-            385..386 's': Option<i32>
+            13..14 'f': F
+            59..89 '{     ...f(s) }': T
+            69..70 's': Option<i32>
+            73..77 'None': Option<i32>
+            83..84 'f': F
+            83..87 'f(s)': T
+            85..86 's': Option<i32>
         "#]],
     );
 }
@@ -3181,17 +3063,7 @@ fn foo() {
 fn infer_dyn_fn_output() {
     check_types(
         r#"
-#[lang = "fn_once"]
-pub trait FnOnce<Args> {
-    type Output;
-    extern "rust-call" fn call_once(self, args: Args) -> Self::Output;
-}
-
-#[lang = "fn"]
-pub trait Fn<Args>: FnOnce<Args> {
-    extern "rust-call" fn call(&self, args: Args) -> Self::Output;
-}
-
+//- minicore: fn
 fn foo() {
     let f: &dyn Fn() -> i32;
     f();
@@ -3204,12 +3076,7 @@ fn foo() {
 fn infer_dyn_fn_once_output() {
     check_types(
         r#"
-#[lang = "fn_once"]
-pub trait FnOnce<Args> {
-    type Output;
-    extern "rust-call" fn call_once(self, args: Args) -> Self::Output;
-}
-
+//- minicore: fn
 fn foo() {
     let f: dyn FnOnce() -> i32;
     f();
@@ -3644,20 +3511,16 @@ fn main() {
 fn fn_returning_unit() {
     check_infer_with_mismatches(
         r#"
-#[lang = "fn_once"]
-trait FnOnce<Args> {
-    type Output;
-}
-
+//- minicore: fn
 fn test<F: FnOnce()>(f: F) {
     let _: () = f();
 }"#,
         expect![[r#"
-            82..83 'f': F
-            88..112 '{     ...f(); }': ()
-            98..99 '_': ()
-            106..107 'f': F
-            106..109 'f()': ()
+            21..22 'f': F
+            27..51 '{     ...f(); }': ()
+            37..38 '_': ()
+            45..46 'f': F
+            45..48 'f()': ()
         "#]],
     );
 }
@@ -3696,16 +3559,7 @@ impl foo::Foo for u32 {
 fn infer_async_ret_type() {
     check_types(
         r#"
-//- /main.rs crate:main deps:core
-
-enum Result<T, E> {
-    Ok(T),
-    Err(E),
-}
-
-use Result::*;
-
-
+//- minicore: future, result
 struct Fooey;
 
 impl Fooey {
@@ -3728,13 +3582,71 @@ async fn get_accounts() -> Result<u32, ()> {
     //                      ^ u32
     Ok(ret)
 }
+"#,
+    );
+}
 
-//- /core.rs crate:core
-#[prelude_import] use future::*;
-mod future {
-    #[lang = "future_trait"]
-    trait Future {
-        type Output;
+#[test]
+fn local_impl_1() {
+    check_types(
+        r#"
+trait Trait<T> {
+    fn foo(&self) -> T;
+}
+
+fn test() {
+    struct S;
+    impl Trait<u32> for S {
+        fn foo(&self) { 0 }
+    }
+
+    S.foo();
+ // ^^^^^^^ u32
+}
+"#,
+    );
+}
+
+#[test]
+fn local_impl_2() {
+    check_types(
+        r#"
+struct S;
+
+fn test() {
+    trait Trait<T> {
+        fn foo(&self) -> T;
+    }
+    impl Trait<u32> for S {
+        fn foo(&self) { 0 }
+    }
+
+    S.foo();
+ // ^^^^^^^ u32
+}
+"#,
+    );
+}
+
+#[test]
+fn local_impl_3() {
+    check_types(
+        r#"
+trait Trait<T> {
+    fn foo(&self) -> T;
+}
+
+fn test() {
+    struct S1;
+    {
+        struct S2;
+
+        impl Trait<S1> for S2 {
+            fn foo(&self) { S1 }
+        }
+
+        S2.foo();
+     // ^^^^^^^^ S1
     }
 }
 "#,