16 files changed, 308 insertions, 49 deletions

diff --git a/crates/ra_hir_ty/src/autoderef.rs b/crates/ra_hir_ty/src/autoderef.rs
index ee48fa537..f32d5786a 100644
--- a/crates/ra_hir_ty/src/autoderef.rs
+++ b/crates/ra_hir_ty/src/autoderef.rs
@@ -48,7 +48,7 @@ fn deref_by_trait(
     krate: CrateId,
     ty: InEnvironment<&Canonical<Ty>>,
 ) -> Option<Canonical<Ty>> {
-    let deref_trait = match db.lang_item(krate.into(), "deref".into())? {
+    let deref_trait = match db.lang_item(krate, "deref".into())? {
         LangItemTarget::TraitId(it) => it,
         _ => return None,
     };
@@ -78,7 +78,7 @@ fn deref_by_trait(
 
     let canonical = super::Canonical { num_vars: 1 + ty.value.num_vars, value: in_env };
 
-    let solution = db.trait_solve(krate.into(), canonical)?;
+    let solution = db.trait_solve(krate, canonical)?;
 
     match &solution {
         Solution::Unique(vars) => {
diff --git a/crates/ra_hir_ty/src/infer.rs b/crates/ra_hir_ty/src/infer.rs
index 98ba05fc2..e97b81473 100644
--- a/crates/ra_hir_ty/src/infer.rs
+++ b/crates/ra_hir_ty/src/infer.rs
@@ -196,7 +196,12 @@ struct InferenceContext<'a, D: HirDatabase> {
     trait_env: Arc<TraitEnvironment>,
     obligations: Vec<Obligation>,
     result: InferenceResult,
-    /// The return type of the function being inferred.
+    /// The return type of the function being inferred, or the closure if we're
+    /// currently within one.
+    ///
+    /// We might consider using a nested inference context for checking
+    /// closures, but currently this is the only field that will change there,
+    /// so it doesn't make sense.
     return_ty: Ty,
 
     /// Impls of `CoerceUnsized` used in coercion.
@@ -363,14 +368,26 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
     }
 
     fn resolve_associated_type(&mut self, inner_ty: Ty, assoc_ty: Option<TypeAliasId>) -> Ty {
+        self.resolve_associated_type_with_params(inner_ty, assoc_ty, &[])
+    }
+
+    fn resolve_associated_type_with_params(
+        &mut self,
+        inner_ty: Ty,
+        assoc_ty: Option<TypeAliasId>,
+        params: &[Ty],
+    ) -> Ty {
         match assoc_ty {
             Some(res_assoc_ty) => {
                 let ty = self.table.new_type_var();
+                let builder = Substs::build_for_def(self.db, res_assoc_ty)
+                    .push(inner_ty)
+                    .fill(params.iter().cloned());
                 let projection = ProjectionPredicate {
                     ty: ty.clone(),
                     projection_ty: ProjectionTy {
                         associated_ty: res_assoc_ty,
-                        parameters: Substs::single(inner_ty),
+                        parameters: builder.build(),
                     },
                 };
                 self.obligations.push(Obligation::Projection(projection));
@@ -443,7 +460,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
     }
 
     fn infer_body(&mut self) {
-        self.infer_expr(self.body.body_expr, &Expectation::has_type(self.return_ty.clone()));
+        self.infer_expr_coerce(self.body.body_expr, &Expectation::has_type(self.return_ty.clone()));
     }
 
     fn resolve_into_iter_item(&self) -> Option<TypeAliasId> {
@@ -517,6 +534,12 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
         let struct_ = self.resolver.resolve_known_struct(self.db, &path)?;
         Some(struct_.into())
     }
+
+    fn resolve_ops_index_output(&self) -> Option<TypeAliasId> {
+        let path = path![std::ops::Index];
+        let trait_ = self.resolver.resolve_known_trait(self.db, &path)?;
+        self.db.trait_data(trait_).associated_type_by_name(&name![Output])
+    }
 }
 
 /// The kinds of placeholders we need during type inference. There's separate
diff --git a/crates/ra_hir_ty/src/infer/coerce.rs b/crates/ra_hir_ty/src/infer/coerce.rs
index 0f4dac45e..83c0c2c3f 100644
--- a/crates/ra_hir_ty/src/infer/coerce.rs
+++ b/crates/ra_hir_ty/src/infer/coerce.rs
@@ -134,6 +134,10 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                 }
             }
 
+            (ty_app!(TypeCtor::Closure { .. }, params), ty_app!(TypeCtor::FnPtr { .. })) => {
+                from_ty = params[0].clone();
+            }
+
             _ => {}
         }
 
diff --git a/crates/ra_hir_ty/src/infer/expr.rs b/crates/ra_hir_ty/src/infer/expr.rs
index 924ad3e81..3af05394c 100644
--- a/crates/ra_hir_ty/src/infer/expr.rs
+++ b/crates/ra_hir_ty/src/infer/expr.rs
@@ -8,7 +8,7 @@ use hir_def::{
     expr::{Array, BinaryOp, Expr, ExprId, Literal, Statement, UnaryOp},
     path::{GenericArg, GenericArgs},
     resolver::resolver_for_expr,
-    AdtId, ContainerId, Lookup, StructFieldId,
+    AdtId, AssocContainerId, Lookup, StructFieldId,
 };
 use hir_expand::name::{name, Name};
 use ra_syntax::ast::RangeOp;
@@ -41,7 +41,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
 
     /// Infer type of expression with possibly implicit coerce to the expected type.
     /// Return the type after possible coercion.
-    fn infer_expr_coerce(&mut self, expr: ExprId, expected: &Expectation) -> Ty {
+    pub(super) fn infer_expr_coerce(&mut self, expr: ExprId, expected: &Expectation) -> Ty {
         let ty = self.infer_expr_inner(expr, &expected);
         let ty = if !self.coerce(&ty, &expected.ty) {
             self.result
@@ -102,7 +102,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                 self.infer_expr(*body, &Expectation::has_type(Ty::unit()));
                 Ty::unit()
             }
-            Expr::Lambda { body, args, arg_types } => {
+            Expr::Lambda { body, args, ret_type, arg_types } => {
                 assert_eq!(args.len(), arg_types.len());
 
                 let mut sig_tys = Vec::new();
@@ -118,7 +118,10 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                 }
 
                 // add return type
-                let ret_ty = self.table.new_type_var();
+                let ret_ty = match ret_type {
+                    Some(type_ref) => self.make_ty(type_ref),
+                    None => self.table.new_type_var(),
+                };
                 sig_tys.push(ret_ty.clone());
                 let sig_ty = Ty::apply(
                     TypeCtor::FnPtr { num_args: sig_tys.len() as u16 - 1 },
@@ -134,7 +137,12 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                 // infer the body.
                 self.coerce(&closure_ty, &expected.ty);
 
-                self.infer_expr(*body, &Expectation::has_type(ret_ty));
+                let prev_ret_ty = std::mem::replace(&mut self.return_ty, ret_ty.clone());
+
+                self.infer_expr_coerce(*body, &Expectation::has_type(ret_ty));
+
+                self.return_ty = prev_ret_ty;
+
                 closure_ty
             }
             Expr::Call { callee, args } => {
@@ -192,6 +200,9 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
             Expr::Return { expr } => {
                 if let Some(expr) = expr {
                     self.infer_expr_coerce(*expr, &Expectation::has_type(self.return_ty.clone()));
+                } else {
+                    let unit = Ty::unit();
+                    self.coerce(&unit, &self.return_ty.clone());
                 }
                 Ty::simple(TypeCtor::Never)
             }
@@ -422,10 +433,14 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                 }
             }
             Expr::Index { base, index } => {
-                let _base_ty = self.infer_expr_inner(*base, &Expectation::none());
-                let _index_ty = self.infer_expr(*index, &Expectation::none());
-                // FIXME: use `std::ops::Index::Output` to figure out the real return type
-                Ty::Unknown
+                let base_ty = self.infer_expr_inner(*base, &Expectation::none());
+                let index_ty = self.infer_expr(*index, &Expectation::none());
+
+                self.resolve_associated_type_with_params(
+                    base_ty,
+                    self.resolve_ops_index_output(),
+                    &[index_ty],
+                )
             }
             Expr::Tuple { exprs } => {
                 let mut tys = match &expected.ty {
@@ -672,7 +687,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                 // add obligation for trait implementation, if this is a trait method
                 match def {
                     CallableDef::FunctionId(f) => {
-                        if let ContainerId::TraitId(trait_) = f.lookup(self.db).container {
+                        if let AssocContainerId::TraitId(trait_) = f.lookup(self.db).container {
                             // construct a TraitDef
                             let substs =
                                 a_ty.parameters.prefix(generics(self.db, trait_.into()).len());
diff --git a/crates/ra_hir_ty/src/infer/path.rs b/crates/ra_hir_ty/src/infer/path.rs
index 402a89386..ffd358367 100644
--- a/crates/ra_hir_ty/src/infer/path.rs
+++ b/crates/ra_hir_ty/src/infer/path.rs
@@ -5,7 +5,7 @@ use std::iter;
 use hir_def::{
     path::{Path, PathSegment},
     resolver::{ResolveValueResult, Resolver, TypeNs, ValueNs},
-    AssocItemId, ContainerId, Lookup,
+    AssocContainerId, AssocItemId, Lookup,
 };
 use hir_expand::name::Name;
 
@@ -209,7 +209,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                     AssocItemId::TypeAliasId(_) => unreachable!(),
                 };
                 let substs = match container {
-                    ContainerId::ImplId(impl_id) => {
+                    AssocContainerId::ImplId(impl_id) => {
                         let impl_substs = Substs::build_for_def(self.db, impl_id)
                             .fill(iter::repeat_with(|| self.table.new_type_var()))
                             .build();
@@ -221,7 +221,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                         self.unify(&impl_self_ty, &ty);
                         Some(substs)
                     }
-                    ContainerId::TraitId(trait_) => {
+                    AssocContainerId::TraitId(trait_) => {
                         // we're picking this method
                         let trait_substs = Substs::build_for_def(self.db, trait_)
                             .push(ty.clone())
@@ -237,7 +237,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                         }));
                         Some(substs)
                     }
-                    ContainerId::ModuleId(_) => None,
+                    AssocContainerId::ContainerId(_) => None,
                 };
 
                 self.write_assoc_resolution(id, item.into());
diff --git a/crates/ra_hir_ty/src/lib.rs b/crates/ra_hir_ty/src/lib.rs
index 7ca9e6b8a..48abf97c9 100644
--- a/crates/ra_hir_ty/src/lib.rs
+++ b/crates/ra_hir_ty/src/lib.rs
@@ -44,8 +44,8 @@ use std::sync::Arc;
 use std::{fmt, iter, mem};
 
 use hir_def::{
-    expr::ExprId, type_ref::Mutability, AdtId, ContainerId, DefWithBodyId, GenericDefId, HasModule,
-    Lookup, TraitId, TypeAliasId,
+    expr::ExprId, type_ref::Mutability, AdtId, AssocContainerId, DefWithBodyId, GenericDefId,
+    HasModule, Lookup, TraitId, TypeAliasId,
 };
 use hir_expand::name::Name;
 use ra_db::{impl_intern_key, salsa, CrateId};
@@ -251,7 +251,7 @@ impl ProjectionTy {
 
     fn trait_(&self, db: &impl HirDatabase) -> TraitId {
         match self.associated_ty.lookup(db).container {
-            ContainerId::TraitId(it) => it,
+            AssocContainerId::TraitId(it) => it,
             _ => panic!("projection ty without parent trait"),
         }
     }
@@ -919,7 +919,7 @@ impl HirDisplay for ApplicationTy {
                         {
                             Option::None => self.parameters.0.as_ref(),
                             Option::Some(default_parameters) => {
-                                for (i, parameter) in self.parameters.into_iter().enumerate() {
+                                for (i, parameter) in self.parameters.iter().enumerate() {
                                     match (parameter, default_parameters.get(i)) {
                                         (&Ty::Unknown, _) | (_, None) => {
                                             non_default_parameters.push(parameter.clone())
@@ -943,7 +943,7 @@ impl HirDisplay for ApplicationTy {
             }
             TypeCtor::AssociatedType(type_alias) => {
                 let trait_ = match type_alias.lookup(f.db).container {
-                    ContainerId::TraitId(it) => it,
+                    AssocContainerId::TraitId(it) => it,
                     _ => panic!("not an associated type"),
                 };
                 let trait_name = f.db.trait_data(trait_).name.clone();
diff --git a/crates/ra_hir_ty/src/lower.rs b/crates/ra_hir_ty/src/lower.rs
index 2b84309d7..af3db2e1d 100644
--- a/crates/ra_hir_ty/src/lower.rs
+++ b/crates/ra_hir_ty/src/lower.rs
@@ -697,8 +697,8 @@ impl CallableDef {
     pub fn krate(self, db: &impl HirDatabase) -> CrateId {
         match self {
             CallableDef::FunctionId(f) => f.lookup(db).module(db),
-            CallableDef::StructId(s) => s.lookup(db).container,
-            CallableDef::EnumVariantId(e) => e.parent.lookup(db).container,
+            CallableDef::StructId(s) => s.lookup(db).container.module(db),
+            CallableDef::EnumVariantId(e) => e.parent.lookup(db).container.module(db),
         }
         .krate
     }
diff --git a/crates/ra_hir_ty/src/method_resolution.rs b/crates/ra_hir_ty/src/method_resolution.rs
index 848e306e9..888dc3116 100644
--- a/crates/ra_hir_ty/src/method_resolution.rs
+++ b/crates/ra_hir_ty/src/method_resolution.rs
@@ -6,8 +6,8 @@ use std::sync::Arc;
 
 use arrayvec::ArrayVec;
 use hir_def::{
-    lang_item::LangItemTarget, resolver::Resolver, type_ref::Mutability, AssocItemId, FunctionId,
-    HasModule, ImplId, Lookup, TraitId,
+    lang_item::LangItemTarget, resolver::Resolver, type_ref::Mutability, AssocContainerId,
+    AssocItemId, FunctionId, HasModule, ImplId, Lookup, TraitId,
 };
 use hir_expand::name::Name;
 use ra_db::CrateId;
@@ -58,7 +58,7 @@ impl CrateImplBlocks {
 
         let crate_def_map = db.crate_def_map(krate);
         for (_module_id, module_data) in crate_def_map.modules.iter() {
-            for &impl_id in module_data.impls.iter() {
+            for impl_id in module_data.scope.impls() {
                 match db.impl_trait(impl_id) {
                     Some(tr) => {
                         res.impls_by_trait.entry(tr.trait_).or_default().push(impl_id);
@@ -134,7 +134,7 @@ impl Ty {
                 LangItemTarget::ImplBlockId(it) => Some(it),
                 _ => None,
             })
-            .map(|it| it.lookup(db).container.krate)
+            .map(|it| it.lookup(db).container.module(db).krate)
             .collect();
         Some(res)
     }
@@ -451,12 +451,12 @@ fn transform_receiver_ty(
     self_ty: &Canonical<Ty>,
 ) -> Option<Ty> {
     let substs = match function_id.lookup(db).container {
-        hir_def::ContainerId::TraitId(_) => Substs::build_for_def(db, function_id)
+        AssocContainerId::TraitId(_) => Substs::build_for_def(db, function_id)
             .push(self_ty.value.clone())
             .fill_with_unknown()
             .build(),
-        hir_def::ContainerId::ImplId(impl_id) => inherent_impl_substs(db, impl_id, &self_ty)?,
-        hir_def::ContainerId::ModuleId(_) => unreachable!(),
+        AssocContainerId::ImplId(impl_id) => inherent_impl_substs(db, impl_id, &self_ty)?,
+        AssocContainerId::ContainerId(_) => unreachable!(),
     };
     let sig = db.callable_item_signature(function_id.into());
     Some(sig.params()[0].clone().subst(&substs))
diff --git a/crates/ra_hir_ty/src/test_db.rs b/crates/ra_hir_ty/src/test_db.rs
index 476f6df52..1a31b587b 100644
--- a/crates/ra_hir_ty/src/test_db.rs
+++ b/crates/ra_hir_ty/src/test_db.rs
@@ -98,7 +98,7 @@ impl TestDB {
                     }
                 }
 
-                for &impl_id in crate_def_map[module_id].impls.iter() {
+                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 {
diff --git a/crates/ra_hir_ty/src/tests.rs b/crates/ra_hir_ty/src/tests.rs
index d724ee122..d447b4571 100644
--- a/crates/ra_hir_ty/src/tests.rs
+++ b/crates/ra_hir_ty/src/tests.rs
@@ -182,7 +182,7 @@ fn visit_module(
             _ => (),
         }
     }
-    for &impl_id in crate_def_map[module_id].impls.iter() {
+    for impl_id in crate_def_map[module_id].scope.impls() {
         let impl_data = db.impl_data(impl_id);
         for &item in impl_data.items.iter() {
             match item {
diff --git a/crates/ra_hir_ty/src/tests/coercion.rs b/crates/ra_hir_ty/src/tests/coercion.rs
index ac9e3872a..7e99a42ed 100644
--- a/crates/ra_hir_ty/src/tests/coercion.rs
+++ b/crates/ra_hir_ty/src/tests/coercion.rs
@@ -370,6 +370,22 @@ fn test() {
 }
 
 #[test]
+fn return_coerce_unknown() {
+    assert_snapshot!(
+        infer_with_mismatches(r#"
+fn foo() -> u32 {
+    return unknown;
+}
+"#, true),
+        @r###"
+    [17; 40) '{     ...own; }': !
+    [23; 37) 'return unknown': !
+    [30; 37) 'unknown': u32
+    "###
+    );
+}
+
+#[test]
 fn coerce_autoderef() {
     assert_snapshot!(
         infer_with_mismatches(r#"
@@ -440,3 +456,73 @@ fn test() {
     "###
     );
 }
+
+#[test]
+fn closure_return_coerce() {
+    assert_snapshot!(
+        infer_with_mismatches(r#"
+fn foo() {
+    let x = || {
+        if true {
+            return &1u32;
+        }
+        &&1u32
+    };
+}
+"#, true),
+        @r###"
+    [10; 106) '{     ...  }; }': ()
+    [20; 21) 'x': || -> &u32
+    [24; 103) '|| {  ...     }': || -> &u32
+    [27; 103) '{     ...     }': &u32
+    [37; 82) 'if tru...     }': ()
+    [40; 44) 'true': bool
+    [45; 82) '{     ...     }': !
+    [59; 71) 'return &1u32': !
+    [66; 71) '&1u32': &u32
+    [67; 71) '1u32': u32
+    [91; 97) '&&1u32': &&u32
+    [92; 97) '&1u32': &u32
+    [93; 97) '1u32': u32
+    "###
+    );
+}
+
+#[test]
+fn coerce_fn_item_to_fn_ptr() {
+    assert_snapshot!(
+        infer_with_mismatches(r#"
+fn foo(x: u32) -> isize { 1 }
+fn test() {
+    let f: fn(u32) -> isize = foo;
+}
+"#, true),
+        @r###"
+    [8; 9) 'x': u32
+    [25; 30) '{ 1 }': isize
+    [27; 28) '1': isize
+    [41; 79) '{     ...foo; }': ()
+    [51; 52) 'f': fn(u32) -> isize
+    [73; 76) 'foo': fn foo(u32) -> isize
+    "###
+    );
+}
+
+#[test]
+fn coerce_closure_to_fn_ptr() {
+    assert_snapshot!(
+        infer_with_mismatches(r#"
+fn test() {
+    let f: fn(u32) -> isize = |x| { 1 };
+}
+"#, true),
+        @r###"
+    [11; 55) '{     ...1 }; }': ()
+    [21; 22) 'f': fn(u32) -> isize
+    [43; 52) '|x| { 1 }': |u32| -> isize
+    [44; 45) 'x': u32
+    [47; 52) '{ 1 }': isize
+    [49; 50) '1': isize
+    "###
+    );
+}
diff --git a/crates/ra_hir_ty/src/tests/macros.rs b/crates/ra_hir_ty/src/tests/macros.rs
index 812f171db..69c695cc8 100644
--- a/crates/ra_hir_ty/src/tests/macros.rs
+++ b/crates/ra_hir_ty/src/tests/macros.rs
@@ -183,6 +183,48 @@ fn test() { S.foo()<|>; }
 }
 
 #[test]
+fn infer_impl_items_generated_by_macros() {
+    let t = type_at(
+        r#"
+//- /main.rs
+macro_rules! m {
+    () => (fn foo(&self) -> u128 {0})
+}
+struct S;
+impl S {
+    m!();
+}
+
+fn test() { S.foo()<|>; }
+"#,
+    );
+    assert_eq!(t, "u128");
+}
+
+#[test]
+fn infer_impl_items_generated_by_macros_chain() {
+    let t = type_at(
+        r#"
+//- /main.rs
+macro_rules! m_inner {
+    () => {fn foo(&self) -> u128 {0}}
+}
+macro_rules! m {
+    () => {m_inner!();}
+}
+
+struct S;
+impl S {
+    m!();
+}
+
+fn test() { S.foo()<|>; }
+"#,
+    );
+    assert_eq!(t, "u128");
+}
+
+#[test]
 fn infer_macro_with_dollar_crate_is_correct_in_expr() {
     let (db, pos) = TestDB::with_position(
         r#"
diff --git a/crates/ra_hir_ty/src/tests/simple.rs b/crates/ra_hir_ty/src/tests/simple.rs
index 18976c9ae..6fe647a5e 100644
--- a/crates/ra_hir_ty/src/tests/simple.rs
+++ b/crates/ra_hir_ty/src/tests/simple.rs
@@ -1606,3 +1606,58 @@ fn main() {
     );
     assert_eq!(t, "u32");
 }
+
+#[test]
+fn closure_return() {
+    assert_snapshot!(
+        infer(r#"
+fn foo() -> u32 {
+    let x = || -> usize { return 1; };
+}
+"#),
+        @r###"
+    [17; 59) '{     ...; }; }': ()
+    [27; 28) 'x': || -> usize
+    [31; 56) '|| -> ...n 1; }': || -> usize
+    [43; 56) '{ return 1; }': !
+    [45; 53) 'return 1': !
+    [52; 53) '1': usize
+    "###
+    );
+}
+
+#[test]
+fn closure_return_unit() {
+    assert_snapshot!(
+        infer(r#"
+fn foo() -> u32 {
+    let x = || { return; };
+}
+"#),
+        @r###"
+    [17; 48) '{     ...; }; }': ()
+    [27; 28) 'x': || -> ()
+    [31; 45) '|| { return; }': || -> ()
+    [34; 45) '{ return; }': !
+    [36; 42) 'return': !
+    "###
+    );
+}
+
+#[test]
+fn closure_return_inferred() {
+    assert_snapshot!(
+        infer(r#"
+fn foo() -> u32 {
+    let x = || { "test" };
+}
+"#),
+        @r###"
+    [17; 47) '{     ..." }; }': ()
+    [27; 28) 'x': || -> &str
+    [31; 44) '|| { "test" }': || -> &str
+    [34; 44) '{ "test" }': &str
+    [36; 42) '"test"': &str
+    "###
+    );
+}
diff --git a/crates/ra_hir_ty/src/tests/traits.rs b/crates/ra_hir_ty/src/tests/traits.rs
index 802937cb0..76e2198b6 100644
--- a/crates/ra_hir_ty/src/tests/traits.rs
+++ b/crates/ra_hir_ty/src/tests/traits.rs
@@ -393,11 +393,11 @@ fn test() -> u64 {
     [54; 55) 'a': S
     [58; 59) 'S': S(fn(u32) -> u64) -> S
     [58; 68) 'S(|i| 2*i)': S
-    [60; 67) '|i| 2*i': |i32| -> i32
-    [61; 62) 'i': i32
-    [64; 65) '2': i32
-    [64; 67) '2*i': i32
-    [66; 67) 'i': i32
+    [60; 67) '|i| 2*i': |u32| -> u64
+    [61; 62) 'i': u32
+    [64; 65) '2': u32
+    [64; 67) '2*i': u32
+    [66; 67) 'i': u32
     [78; 79) 'b': u64
     [82; 83) 'a': S
     [82; 85) 'a.0': fn(u32) -> u64
@@ -427,6 +427,38 @@ fn indexing_arrays() {
 }
 
 #[test]
+fn infer_ops_index() {
+    let (db, pos) = TestDB::with_position(
+        r#"
+//- /main.rs crate:main deps:std
+
+struct Bar;
+struct Foo;
+
+impl std::ops::Index<u32> for Bar {
+    type Output = Foo;
+}
+
+fn test() {
+    let a = Bar;
+    let b = a[1];
+    b<|>;
+}
+
+//- /std.rs crate:std
+
+#[prelude_import] use ops::*;
+mod ops {
+    pub trait Index<Idx> {
+        type Output;
+    }
+}
+"#,
+    );
+    assert_eq!("Foo", type_at_pos(&db, pos));
+}
+
+#[test]
 fn deref_trait() {
     let t = type_at(
         r#"
diff --git a/crates/ra_hir_ty/src/traits/chalk.rs b/crates/ra_hir_ty/src/traits/chalk.rs
index fc21872b2..5eb032d86 100644
--- a/crates/ra_hir_ty/src/traits/chalk.rs
+++ b/crates/ra_hir_ty/src/traits/chalk.rs
@@ -9,7 +9,9 @@ use chalk_ir::{
 };
 use chalk_rust_ir::{AssociatedTyDatum, AssociatedTyValue, ImplDatum, StructDatum, TraitDatum};
 
-use hir_def::{AssocItemId, ContainerId, GenericDefId, ImplId, Lookup, TraitId, TypeAliasId};
+use hir_def::{
+    AssocContainerId, AssocItemId, GenericDefId, HasModule, ImplId, Lookup, TraitId, TypeAliasId,
+};
 use ra_db::{
     salsa::{InternId, InternKey},
     CrateId,
@@ -542,7 +544,7 @@ pub(crate) fn associated_ty_data_query(
     debug!("associated_ty_data {:?}", id);
     let type_alias: TypeAliasId = from_chalk(db, id);
     let trait_ = match type_alias.lookup(db).container {
-        ContainerId::TraitId(t) => t,
+        AssocContainerId::TraitId(t) => t,
         _ => panic!("associated type not in trait"),
     };
     let generic_params = generics(db, type_alias.into());
@@ -591,7 +593,7 @@ pub(crate) fn trait_datum_query(
     let bound_vars = Substs::bound_vars(&generic_params);
     let flags = chalk_rust_ir::TraitFlags {
         auto: trait_data.auto,
-        upstream: trait_.lookup(db).container.krate != krate,
+        upstream: trait_.lookup(db).container.module(db).krate != krate,
         non_enumerable: true,
         coinductive: false, // only relevant for Chalk testing
         // FIXME set these flags correctly
@@ -671,7 +673,7 @@ fn impl_block_datum(
     let bound_vars = Substs::bound_vars(&generic_params);
     let trait_ref = trait_ref.subst(&bound_vars);
     let trait_ = trait_ref.trait_;
-    let impl_type = if impl_id.lookup(db).container.krate == krate {
+    let impl_type = if impl_id.lookup(db).container.module(db).krate == krate {
         chalk_rust_ir::ImplType::Local
     } else {
         chalk_rust_ir::ImplType::External
@@ -755,7 +757,7 @@ fn type_alias_associated_ty_value(
 ) -> Arc<AssociatedTyValue<ChalkIr>> {
     let type_alias_data = db.type_alias_data(type_alias);
     let impl_id = match type_alias.lookup(db).container {
-        ContainerId::ImplId(it) => it,
+        AssocContainerId::ImplId(it) => it,
         _ => panic!("assoc ty value should be in impl"),
     };
 
diff --git a/crates/ra_hir_ty/src/utils.rs b/crates/ra_hir_ty/src/utils.rs
index 29799a8cb..0b1806a84 100644
--- a/crates/ra_hir_ty/src/utils.rs
+++ b/crates/ra_hir_ty/src/utils.rs
@@ -9,7 +9,7 @@ use hir_def::{
     path::Path,
     resolver::{HasResolver, TypeNs},
     type_ref::TypeRef,
-    ContainerId, GenericDefId, Lookup, TraitId, TypeAliasId, TypeParamId, VariantId,
+    AssocContainerId, GenericDefId, Lookup, TraitId, TypeAliasId, TypeParamId, VariantId,
 };
 use hir_expand::name::{name, Name};
 
@@ -155,8 +155,8 @@ fn parent_generic_def(db: &impl DefDatabase, def: GenericDefId) -> Option<Generi
     };
 
     match container {
-        ContainerId::ImplId(it) => Some(it.into()),
-        ContainerId::TraitId(it) => Some(it.into()),
-        ContainerId::ModuleId(_) => None,
+        AssocContainerId::ImplId(it) => Some(it.into()),
+        AssocContainerId::TraitId(it) => Some(it.into()),
+        AssocContainerId::ContainerId(_) => None,
     }
 }