5 files changed, 68 insertions, 25 deletions

diff --git a/crates/ra_hir/src/db.rs b/crates/ra_hir/src/db.rs
index ec931b34f..693cd40cf 100644
--- a/crates/ra_hir/src/db.rs
+++ b/crates/ra_hir/src/db.rs
@@ -18,8 +18,8 @@ pub use hir_ty::db::{
     GenericDefaultsQuery, GenericPredicatesForParamQuery, GenericPredicatesQuery, HirDatabase,
     HirDatabaseStorage, ImplDatumQuery, ImplSelfTyQuery, ImplTraitQuery, ImplsForTraitQuery,
     ImplsInCrateQuery, InferQueryQuery, InternAssocTyValueQuery, InternChalkImplQuery,
-    InternTypeCtorQuery, InternTypeParamIdQuery, StructDatumQuery, TraitDatumQuery,
-    TraitSolveQuery, TyQuery, ValueTyQuery,
+    InternTypeCtorQuery, InternTypeParamIdQuery, ReturnTypeImplTraitsQuery, StructDatumQuery,
+    TraitDatumQuery, TraitSolveQuery, TyQuery, ValueTyQuery,
 };
 
 #[test]
diff --git a/crates/ra_hir_ty/src/display.rs b/crates/ra_hir_ty/src/display.rs
index 3e63a2415..3c97e1354 100644
--- a/crates/ra_hir_ty/src/display.rs
+++ b/crates/ra_hir_ty/src/display.rs
@@ -4,7 +4,7 @@ use std::fmt;
 
 use crate::{
     db::HirDatabase, utils::generics, ApplicationTy, CallableDef, FnSig, GenericPredicate,
-    Obligation, ProjectionTy, Substs, TraitRef, Ty, TypeCtor,
+    Obligation, OpaqueTyId, ProjectionTy, Substs, TraitRef, Ty, TypeCtor,
 };
 use hir_def::{
     find_path, generics::TypeParamProvenance, item_scope::ItemInNs, AdtId, AssocContainerId,
@@ -361,7 +361,7 @@ impl HirDisplay for ApplicationTy {
             }
             TypeCtor::OpaqueType(opaque_ty_id) => {
                 let bounds = match opaque_ty_id {
-                    crate::OpaqueTyId::ReturnTypeImplTrait(func, idx) => {
+                    OpaqueTyId::ReturnTypeImplTrait(func, idx) => {
                         let datas =
                             f.db.return_type_impl_traits(func).expect("impl trait id without data");
                         let data = (*datas)
@@ -448,7 +448,7 @@ impl HirDisplay for Ty {
             }
             Ty::Opaque(opaque_ty) => {
                 let bounds = match opaque_ty.opaque_ty_id {
-                    crate::OpaqueTyId::ReturnTypeImplTrait(func, idx) => {
+                    OpaqueTyId::ReturnTypeImplTrait(func, idx) => {
                         let datas =
                             f.db.return_type_impl_traits(func).expect("impl trait id without data");
                         let data = (*datas)
diff --git a/crates/ra_hir_ty/src/lower.rs b/crates/ra_hir_ty/src/lower.rs
index dfc018b0b..a05cbd7fc 100644
--- a/crates/ra_hir_ty/src/lower.rs
+++ b/crates/ra_hir_ty/src/lower.rs
@@ -21,8 +21,10 @@ use hir_def::{
     HasModule, ImplId, LocalFieldId, Lookup, StaticId, StructId, TraitId, TypeAliasId, TypeParamId,
     UnionId, VariantId,
 };
+use hir_expand::name::Name;
 use ra_arena::map::ArenaMap;
 use ra_db::CrateId;
+use test_utils::mark;
 
 use crate::{
     db::HirDatabase,
@@ -35,7 +37,6 @@ use crate::{
     ProjectionPredicate, ProjectionTy, ReturnTypeImplTrait, ReturnTypeImplTraits, Substs,
     TraitEnvironment, TraitRef, Ty, TypeCtor, TypeWalk,
 };
-use hir_expand::name::Name;
 
 #[derive(Debug)]
 pub struct TyLoweringContext<'a> {
@@ -220,10 +221,7 @@ impl Ty {
 
                         let func = match ctx.resolver.generic_def() {
                             Some(GenericDefId::FunctionId(f)) => f,
-                            _ => {
-                                // this shouldn't happen
-                                return (Ty::Unknown, None);
-                            }
+                            _ => panic!("opaque impl trait lowering in non-function"),
                         };
                         let impl_trait_id = OpaqueTyId::ReturnTypeImplTrait(func, idx);
                         let generics = generics(ctx.db.upcast(), func.into());
@@ -719,6 +717,7 @@ fn assoc_type_bindings_from_type_bound<'a>(
 
 impl ReturnTypeImplTrait {
     fn from_hir(ctx: &TyLoweringContext, bounds: &[TypeBound]) -> Self {
+        mark::hit!(lower_rpit);
         let self_ty = Ty::Bound(BoundVar::new(DebruijnIndex::INNERMOST, 0));
         let predicates = ctx.with_shifted_in(DebruijnIndex::ONE, |ctx| {
             bounds
diff --git a/crates/ra_hir_ty/src/tests/traits.rs b/crates/ra_hir_ty/src/tests/traits.rs
index d83dc6d79..0c538a62d 100644
--- a/crates/ra_hir_ty/src/tests/traits.rs
+++ b/crates/ra_hir_ty/src/tests/traits.rs
@@ -1160,7 +1160,37 @@ fn test(x: impl Trait<u64>, y: &impl Trait<u64>) {
 }
 
 #[test]
-fn return_pos_impl_trait() {
+fn simple_return_pos_impl_trait() {
+    mark::check!(lower_rpit);
+    assert_snapshot!(
+        infer(r#"
+trait Trait<T> {
+    fn foo(&self) -> T;
+}
+fn bar() -> impl Trait<u64> { loop {} }
+
+fn test() {
+    let a = bar();
+    a.foo();
+}
+"#),
+        @r###"
+    30..34 'self': &Self
+    72..83 '{ loop {} }': !
+    74..81 'loop {}': !
+    79..81 '{}': ()
+    95..130 '{     ...o(); }': ()
+    105..106 'a': impl Trait<u64>
+    109..112 'bar': fn bar() -> impl Trait<u64>
+    109..114 'bar()': impl Trait<u64>
+    120..121 'a': impl Trait<u64>
+    120..127 'a.foo()': u64
+    "###
+    );
+}
+
+#[test]
+fn more_return_pos_impl_trait() {
     assert_snapshot!(
         infer(r#"
 trait Iterator {
@@ -1174,12 +1204,12 @@ fn bar() -> (impl Iterator<Item = impl Trait<u32>>, impl Trait<u64>) { loop {} }
 fn baz<T>(t: T) -> (impl Iterator<Item = impl Trait<T>>, impl Trait<T>) { loop {} }
 
 fn test() {
-    // let (a, b) = bar();
-    // a.next().foo();
-    // b.foo();
+    let (a, b) = bar();
+    a.next().foo();
+    b.foo();
     let (c, d) = baz(1u128);
-    c.next();//.foo();
-    // d.foo();
+    c.next().foo();
+    d.foo();
 }
 "#),
         @r###"
@@ -1192,15 +1222,28 @@ fn test() {
     269..280 '{ loop {} }': ({unknown}, {unknown})
     271..278 'loop {}': !
     276..278 '{}': ()
-    292..429 '{     ...o(); }': ()
-    368..374 '(c, d)': (impl Iterator<Item = impl Trait<u128>>, impl Trait<u128>)
-    369..370 'c': impl Iterator<Item = impl Trait<u128>>
-    372..373 'd': impl Trait<u128>
-    377..380 'baz': fn baz<u128>(u128) -> (impl Iterator<Item = impl Trait<u128>>, impl Trait<u128>)
-    377..387 'baz(1u128)': (impl Iterator<Item = impl Trait<u128>>, impl Trait<u128>)
-    381..386 '1u128': u128
-    393..394 'c': impl Iterator<Item = impl Trait<u128>>
-    393..401 'c.next()': impl Trait<u128>
+    292..414 '{     ...o(); }': ()
+    302..308 '(a, b)': (impl Iterator<Item = impl Trait<u32>>, impl Trait<u64>)
+    303..304 'a': impl Iterator<Item = impl Trait<u32>>
+    306..307 'b': impl Trait<u64>
+    311..314 'bar': fn bar() -> (impl Iterator<Item = impl Trait<u32>>, impl Trait<u64>)
+    311..316 'bar()': (impl Iterator<Item = impl Trait<u32>>, impl Trait<u64>)
+    322..323 'a': impl Iterator<Item = impl Trait<u32>>
+    322..330 'a.next()': impl Trait<u32>
+    322..336 'a.next().foo()': u32
+    342..343 'b': impl Trait<u64>
+    342..349 'b.foo()': u64
+    359..365 '(c, d)': (impl Iterator<Item = impl Trait<u128>>, impl Trait<u128>)
+    360..361 'c': impl Iterator<Item = impl Trait<u128>>
+    363..364 'd': impl Trait<u128>
+    368..371 'baz': fn baz<u128>(u128) -> (impl Iterator<Item = impl Trait<u128>>, impl Trait<u128>)
+    368..378 'baz(1u128)': (impl Iterator<Item = impl Trait<u128>>, impl Trait<u128>)
+    372..377 '1u128': u128
+    384..385 'c': impl Iterator<Item = impl Trait<u128>>
+    384..392 'c.next()': impl Trait<u128>
+    384..398 'c.next().foo()': u128
+    404..405 'd': impl Trait<u128>
+    404..411 'd.foo()': u128
     "###
     );
 }
diff --git a/crates/ra_ide_db/src/change.rs b/crates/ra_ide_db/src/change.rs
index 8446ef88e..1f4d2c076 100644
--- a/crates/ra_ide_db/src/change.rs
+++ b/crates/ra_ide_db/src/change.rs
@@ -369,6 +369,7 @@ impl RootDatabase {
             hir::db::ImplDatumQuery
             hir::db::AssociatedTyValueQuery
             hir::db::TraitSolveQuery
+            hir::db::ReturnTypeImplTraitsQuery
 
             // SymbolsDatabase
             crate::symbol_index::FileSymbolsQuery