4 files changed, 139 insertions, 21 deletions

diff --git a/crates/ra_hir_ty/src/lower.rs b/crates/ra_hir_ty/src/lower.rs
index 6c7bbc448..cc1ac8e3e 100644
--- a/crates/ra_hir_ty/src/lower.rs
+++ b/crates/ra_hir_ty/src/lower.rs
@@ -8,6 +8,8 @@
 use std::iter;
 use std::sync::Arc;
 
+use smallvec::SmallVec;
+
 use hir_def::{
     adt::StructKind,
     builtin_type::BuiltinType,
@@ -360,13 +362,23 @@ impl Ty {
             },
             Some(TypeNs::GenericParam(param_id)) => {
                 let predicates = ctx.db.generic_predicates_for_param(param_id);
-                predicates
+                let mut traits_: Vec<_> = predicates
                     .iter()
                     .filter_map(|pred| match &pred.value {
                         GenericPredicate::Implemented(tr) => Some(tr.trait_),
                         _ => None,
                     })
-                    .collect()
+                    .collect();
+                // Handle `Self::Type` referring to own associated type in trait definitions
+                if let GenericDefId::TraitId(trait_id) = param_id.parent {
+                    let generics = generics(ctx.db.upcast(), trait_id.into());
+                    if generics.params.types[param_id.local_id].provenance
+                        == TypeParamProvenance::TraitSelf
+                    {
+                        traits_.push(trait_id);
+                    }
+                }
+                traits_
             }
             _ => return Ty::Unknown,
         };
@@ -596,21 +608,35 @@ fn assoc_type_bindings_from_type_bound<'a>(
         .into_iter()
         .flat_map(|segment| segment.args_and_bindings.into_iter())
         .flat_map(|args_and_bindings| args_and_bindings.bindings.iter())
-        .map(move |(name, type_ref)| {
+        .flat_map(move |binding| {
             let associated_ty = associated_type_by_name_including_super_traits(
                 ctx.db.upcast(),
                 trait_ref.trait_,
-                &name,
+                &binding.name,
             );
             let associated_ty = match associated_ty {
-                None => return GenericPredicate::Error,
+                None => return SmallVec::<[GenericPredicate; 1]>::new(),
                 Some(t) => t,
             };
             let projection_ty =
                 ProjectionTy { associated_ty, parameters: trait_ref.substs.clone() };
-            let ty = Ty::from_hir(ctx, type_ref);
-            let projection_predicate = ProjectionPredicate { projection_ty, ty };
-            GenericPredicate::Projection(projection_predicate)
+            let mut preds = SmallVec::with_capacity(
+                binding.type_ref.as_ref().map_or(0, |_| 1) + binding.bounds.len(),
+            );
+            if let Some(type_ref) = &binding.type_ref {
+                let ty = Ty::from_hir(ctx, type_ref);
+                let projection_predicate =
+                    ProjectionPredicate { projection_ty: projection_ty.clone(), ty };
+                preds.push(GenericPredicate::Projection(projection_predicate));
+            }
+            for bound in &binding.bounds {
+                preds.extend(GenericPredicate::from_type_bound(
+                    ctx,
+                    bound,
+                    Ty::Projection(projection_ty.clone()),
+                ));
+            }
+            preds
         })
 }
 
diff --git a/crates/ra_hir_ty/src/tests/regression.rs b/crates/ra_hir_ty/src/tests/regression.rs
index 3402e0cb5..d69115a2f 100644
--- a/crates/ra_hir_ty/src/tests/regression.rs
+++ b/crates/ra_hir_ty/src/tests/regression.rs
@@ -451,8 +451,7 @@ pub mod str {
 "#,
     );
 
-    // should be Option<char>, but currently not because of Chalk ambiguity problem
-    assert_eq!("(Option<{unknown}>, Option<{unknown}>)", super::type_at_pos(&db, pos));
+    assert_eq!("(Option<char>, Option<char>)", super::type_at_pos(&db, pos));
 }
 
 #[test]
diff --git a/crates/ra_hir_ty/src/tests/traits.rs b/crates/ra_hir_ty/src/tests/traits.rs
index 22ae6ca90..81c5e6299 100644
--- a/crates/ra_hir_ty/src/tests/traits.rs
+++ b/crates/ra_hir_ty/src/tests/traits.rs
@@ -1803,7 +1803,7 @@ fn test<T, U>() where T::Item: Trait2, T: Trait<U::Item>, U: Trait<()> {
 }
 
 #[test]
-fn unselected_projection_on_trait_self() {
+fn unselected_projection_on_impl_self() {
     assert_snapshot!(infer(
         r#"
 //- /main.rs
@@ -1844,6 +1844,30 @@ impl Trait for S2 {
 }
 
 #[test]
+fn unselected_projection_on_trait_self() {
+    let t = type_at(
+        r#"
+//- /main.rs
+trait Trait {
+    type Item;
+
+    fn f(&self) -> Self::Item { loop {} }
+}
+
+struct S;
+impl Trait for S {
+    type Item = u32;
+}
+
+fn test() {
+    S.f()<|>;
+}
+"#,
+    );
+    assert_eq!(t, "u32");
+}
+
+#[test]
 fn trait_impl_self_ty() {
     let t = type_at(
         r#"
@@ -1924,6 +1948,53 @@ fn test<T, U>() where T: Trait<U::Item>, U: Trait<T::Item> {
 }
 
 #[test]
+fn inline_assoc_type_bounds_1() {
+    let t = type_at(
+        r#"
+//- /main.rs
+trait Iterator {
+    type Item;
+}
+trait OtherTrait<T> {
+    fn foo(&self) -> T;
+}
+
+// workaround for Chalk assoc type normalization problems
+pub struct S<T>;
+impl<T: Iterator> Iterator for S<T> {
+    type Item = <T as Iterator>::Item;
+}
+
+fn test<I: Iterator<Item: OtherTrait<u32>>>() {
+    let x: <S<I> as Iterator>::Item;
+    x.foo()<|>;
+}
+"#,
+    );
+    assert_eq!(t, "u32");
+}
+
+#[test]
+fn inline_assoc_type_bounds_2() {
+    let t = type_at(
+        r#"
+//- /main.rs
+trait Iterator {
+    type Item;
+}
+
+fn test<I: Iterator<Item: Iterator<Item = u32>>>() {
+    let x: <<I as Iterator>::Item as Iterator>::Item;
+    x<|>;
+}
+"#,
+    );
+    // assert_eq!(t, "u32");
+    // doesn't currently work, Chalk #234
+    assert_eq!(t, "{unknown}");
+}
+
+#[test]
 fn unify_impl_trait() {
     assert_snapshot!(
         infer_with_mismatches(r#"
diff --git a/crates/ra_hir_ty/src/traits/chalk/tls.rs b/crates/ra_hir_ty/src/traits/chalk/tls.rs
index d9bbb54a5..fa8e4d1ad 100644
--- a/crates/ra_hir_ty/src/traits/chalk/tls.rs
+++ b/crates/ra_hir_ty/src/traits/chalk/tls.rs
@@ -2,10 +2,11 @@
 use std::fmt;
 
 use chalk_ir::{AliasTy, Goal, Goals, Lifetime, Parameter, ProgramClauseImplication, TypeName};
+use itertools::Itertools;
 
 use super::{from_chalk, Interner};
 use crate::{db::HirDatabase, CallableDef, TypeCtor};
-use hir_def::{AdtId, AssocContainerId, Lookup, TypeAliasId};
+use hir_def::{AdtId, AssocContainerId, DefWithBodyId, Lookup, TypeAliasId};
 
 pub use unsafe_tls::{set_current_program, with_current_program};
 
@@ -69,7 +70,27 @@ impl DebugContext<'_> {
                 write!(f, "{}::{}", trait_name, name)?;
             }
             TypeCtor::Closure { def, expr } => {
-                write!(f, "{{closure {:?} in {:?}}}", expr.into_raw(), def)?;
+                write!(f, "{{closure {:?} in ", expr.into_raw())?;
+                match def {
+                    DefWithBodyId::FunctionId(func) => {
+                        write!(f, "fn {}", self.0.function_data(func).name)?
+                    }
+                    DefWithBodyId::StaticId(s) => {
+                        if let Some(name) = self.0.static_data(s).name.as_ref() {
+                            write!(f, "body of static {}", name)?;
+                        } else {
+                            write!(f, "body of unnamed static {:?}", s)?;
+                        }
+                    }
+                    DefWithBodyId::ConstId(c) => {
+                        if let Some(name) = self.0.const_data(c).name.as_ref() {
+                            write!(f, "body of const {}", name)?;
+                        } else {
+                            write!(f, "body of unnamed const {:?}", c)?;
+                        }
+                    }
+                };
+                write!(f, "}}")?;
             }
         }
         Ok(())
@@ -113,14 +134,15 @@ impl DebugContext<'_> {
         };
         let trait_data = self.0.trait_data(trait_);
         let params = alias.substitution.parameters(&Interner);
-        write!(
-            fmt,
-            "<{:?} as {}<{:?}>>::{}",
-            &params[0],
-            trait_data.name,
-            &params[1..],
-            type_alias_data.name
-        )
+        write!(fmt, "<{:?} as {}", &params[0], trait_data.name,)?;
+        if params.len() > 1 {
+            write!(
+                fmt,
+                "<{}>",
+                &params[1..].iter().format_with(", ", |x, f| f(&format_args!("{:?}", x))),
+            )?;
+        }
+        write!(fmt, ">::{}", type_alias_data.name)
     }
 
     pub fn debug_ty(