10 files changed, 192 insertions, 32 deletions

diff --git a/Cargo.lock b/Cargo.lock
index aca737627..01fa64e6f 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1014,6 +1014,7 @@ dependencies = [
  "chalk-solve",
  "ena",
  "insta",
+ "itertools",
  "log",
  "ra_arena",
  "ra_db",
diff --git a/crates/ra_hir_def/src/data.rs b/crates/ra_hir_def/src/data.rs
index 56a20c5bd..b3c91fea2 100644
--- a/crates/ra_hir_def/src/data.rs
+++ b/crates/ra_hir_def/src/data.rs
@@ -15,7 +15,7 @@ use ra_syntax::ast::{
 use crate::{
     attr::Attrs,
     db::DefDatabase,
-    path::{path, GenericArgs, Path},
+    path::{path, AssociatedTypeBinding, GenericArgs, Path},
     src::HasSource,
     type_ref::{Mutability, TypeBound, TypeRef},
     visibility::RawVisibility,
@@ -95,7 +95,11 @@ fn desugar_future_path(orig: TypeRef) -> Path {
     let path = path![std::future::Future];
     let mut generic_args: Vec<_> = std::iter::repeat(None).take(path.segments.len() - 1).collect();
     let mut last = GenericArgs::empty();
-    last.bindings.push((name![Output], orig));
+    last.bindings.push(AssociatedTypeBinding {
+        name: name![Output],
+        type_ref: Some(orig),
+        bounds: Vec::new(),
+    });
     generic_args.push(Some(Arc::new(last)));
 
     Path::from_known_path(path, generic_args)
diff --git a/crates/ra_hir_def/src/path.rs b/crates/ra_hir_def/src/path.rs
index 91c7b3e09..162b3c8c7 100644
--- a/crates/ra_hir_def/src/path.rs
+++ b/crates/ra_hir_def/src/path.rs
@@ -14,7 +14,10 @@ use hir_expand::{
 use ra_db::CrateId;
 use ra_syntax::ast;
 
-use crate::{type_ref::TypeRef, InFile};
+use crate::{
+    type_ref::{TypeBound, TypeRef},
+    InFile,
+};
 
 #[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
 pub struct ModPath {
@@ -111,7 +114,21 @@ pub struct GenericArgs {
     /// is left out.
     pub has_self_type: bool,
     /// Associated type bindings like in `Iterator<Item = T>`.
-    pub bindings: Vec<(Name, TypeRef)>,
+    pub bindings: Vec<AssociatedTypeBinding>,
+}
+
+/// An associated type binding like in `Iterator<Item = T>`.
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub struct AssociatedTypeBinding {
+    /// The name of the associated type.
+    pub name: Name,
+    /// The type bound to this associated type (in `Item = T`, this would be the
+    /// `T`). This can be `None` if there are bounds instead.
+    pub type_ref: Option<TypeRef>,
+    /// Bounds for the associated type, like in `Iterator<Item:
+    /// SomeOtherTrait>`. (This is the unstable `associated_type_bounds`
+    /// feature.)
+    pub bounds: Vec<TypeBound>,
 }
 
 /// A single generic argument.
diff --git a/crates/ra_hir_def/src/path/lower.rs b/crates/ra_hir_def/src/path/lower.rs
index 0f806d6fb..9ec2e0dcd 100644
--- a/crates/ra_hir_def/src/path/lower.rs
+++ b/crates/ra_hir_def/src/path/lower.rs
@@ -9,11 +9,12 @@ use hir_expand::{
     hygiene::Hygiene,
     name::{name, AsName},
 };
-use ra_syntax::ast::{self, AstNode, TypeAscriptionOwner};
+use ra_syntax::ast::{self, AstNode, TypeAscriptionOwner, TypeBoundsOwner};
 
+use super::AssociatedTypeBinding;
 use crate::{
     path::{GenericArg, GenericArgs, ModPath, Path, PathKind},
-    type_ref::TypeRef,
+    type_ref::{TypeBound, TypeRef},
 };
 
 pub(super) use lower_use::lower_use_tree;
@@ -136,10 +137,16 @@ pub(super) fn lower_generic_args(node: ast::TypeArgList) -> Option<GenericArgs>
     // lifetimes ignored for now
     let mut bindings = Vec::new();
     for assoc_type_arg in node.assoc_type_args() {
+        let assoc_type_arg: ast::AssocTypeArg = assoc_type_arg;
         if let Some(name_ref) = assoc_type_arg.name_ref() {
             let name = name_ref.as_name();
-            let type_ref = TypeRef::from_ast_opt(assoc_type_arg.type_ref());
-            bindings.push((name, type_ref));
+            let type_ref = assoc_type_arg.type_ref().map(TypeRef::from_ast);
+            let bounds = if let Some(l) = assoc_type_arg.type_bound_list() {
+                l.bounds().map(TypeBound::from_ast).collect()
+            } else {
+                Vec::new()
+            };
+            bindings.push(AssociatedTypeBinding { name, type_ref, bounds });
         }
     }
     if args.is_empty() && bindings.is_empty() {
@@ -168,7 +175,11 @@ fn lower_generic_args_from_fn_path(
     }
     if let Some(ret_type) = ret_type {
         let type_ref = TypeRef::from_ast_opt(ret_type.type_ref());
-        bindings.push((name![Output], type_ref))
+        bindings.push(AssociatedTypeBinding {
+            name: name![Output],
+            type_ref: Some(type_ref),
+            bounds: Vec::new(),
+        });
     }
     if args.is_empty() && bindings.is_empty() {
         None
diff --git a/crates/ra_hir_def/src/type_ref.rs b/crates/ra_hir_def/src/type_ref.rs
index ea29c4176..f308c6bdf 100644
--- a/crates/ra_hir_def/src/type_ref.rs
+++ b/crates/ra_hir_def/src/type_ref.rs
@@ -163,8 +163,16 @@ impl TypeRef {
                         let crate::path::GenericArg::Type(type_ref) = arg;
                         go(type_ref, f);
                     }
-                    for (_, type_ref) in &args_and_bindings.bindings {
-                        go(type_ref, f);
+                    for binding in &args_and_bindings.bindings {
+                        if let Some(type_ref) = &binding.type_ref {
+                            go(type_ref, f);
+                        }
+                        for bound in &binding.bounds {
+                            match bound {
+                                TypeBound::Path(path) => go_path(path, f),
+                                TypeBound::Error => (),
+                            }
+                        }
                     }
                 }
             }
diff --git a/crates/ra_hir_ty/Cargo.toml b/crates/ra_hir_ty/Cargo.toml
index 0003456c1..e891d733f 100644
--- a/crates/ra_hir_ty/Cargo.toml
+++ b/crates/ra_hir_ty/Cargo.toml
@@ -8,6 +8,7 @@ authors = ["rust-analyzer developers"]
 doctest = false
 
 [dependencies]
+itertools = "0.9.0"
 arrayvec = "0.5.1"
 smallvec = "1.2.0"
 ena = "0.13.1"
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(