9 files changed, 424 insertions, 72 deletions

diff --git a/crates/ra_hir_ty/src/infer.rs b/crates/ra_hir_ty/src/infer.rs
index 6a53be621..bd4ef69a0 100644
--- a/crates/ra_hir_ty/src/infer.rs
+++ b/crates/ra_hir_ty/src/infer.rs
@@ -667,7 +667,7 @@ impl Expectation {
 }
 
 mod diagnostics {
-    use hir_def::{expr::ExprId, src::HasSource, FunctionId, Lookup};
+    use hir_def::{expr::ExprId, FunctionId};
     use hir_expand::diagnostics::DiagnosticSink;
 
     use crate::{db::HirDatabase, diagnostics::NoSuchField};
@@ -686,10 +686,9 @@ mod diagnostics {
         ) {
             match self {
                 InferenceDiagnostic::NoSuchField { expr, field } => {
-                    let source = owner.lookup(db.upcast()).source(db.upcast());
                     let (_, source_map) = db.body_with_source_map(owner.into());
                     let field = source_map.field_syntax(*expr, *field);
-                    sink.push(NoSuchField { file: source.file_id, field: field.value })
+                    sink.push(NoSuchField { file: field.file_id, field: field.value })
                 }
             }
         }
diff --git a/crates/ra_hir_ty/src/lib.rs b/crates/ra_hir_ty/src/lib.rs
index 279c06d65..a6f56c661 100644
--- a/crates/ra_hir_ty/src/lib.rs
+++ b/crates/ra_hir_ty/src/lib.rs
@@ -66,7 +66,8 @@ pub use autoderef::autoderef;
 pub use infer::{InferTy, InferenceResult};
 pub use lower::CallableDef;
 pub use lower::{
-    callable_item_sig, ImplTraitLoweringMode, TyDefId, TyLoweringContext, ValueTyDefId,
+    associated_type_shorthand_candidates, callable_item_sig, ImplTraitLoweringMode, TyDefId,
+    TyLoweringContext, ValueTyDefId,
 };
 pub use traits::{InEnvironment, Obligation, ProjectionPredicate, TraitEnvironment};
 
@@ -487,6 +488,18 @@ impl<T> Binders<T> {
     pub fn new(num_binders: usize, value: T) -> Self {
         Self { num_binders, value }
     }
+
+    pub fn as_ref(&self) -> Binders<&T> {
+        Binders { num_binders: self.num_binders, value: &self.value }
+    }
+
+    pub fn map<U>(self, f: impl FnOnce(T) -> U) -> Binders<U> {
+        Binders { num_binders: self.num_binders, value: f(self.value) }
+    }
+
+    pub fn filter_map<U>(self, f: impl FnOnce(T) -> Option<U>) -> Option<Binders<U>> {
+        Some(Binders { num_binders: self.num_binders, value: f(self.value)? })
+    }
 }
 
 impl<T: Clone> Binders<&T> {
diff --git a/crates/ra_hir_ty/src/lower.rs b/crates/ra_hir_ty/src/lower.rs
index b57214296..9ad6dbe07 100644
--- a/crates/ra_hir_ty/src/lower.rs
+++ b/crates/ra_hir_ty/src/lower.rs
@@ -17,9 +17,9 @@ use hir_def::{
     path::{GenericArg, Path, PathSegment, PathSegments},
     resolver::{HasResolver, Resolver, TypeNs},
     type_ref::{TypeBound, TypeRef},
-    AdtId, AssocContainerId, ConstId, EnumId, EnumVariantId, FunctionId, GenericDefId, HasModule,
-    ImplId, LocalFieldId, Lookup, StaticId, StructId, TraitId, TypeAliasId, TypeParamId, UnionId,
-    VariantId,
+    AdtId, AssocContainerId, AssocItemId, ConstId, EnumId, EnumVariantId, FunctionId, GenericDefId,
+    HasModule, ImplId, LocalFieldId, Lookup, StaticId, StructId, TraitId, TypeAliasId, TypeParamId,
+    UnionId, VariantId,
 };
 use ra_arena::map::ArenaMap;
 use ra_db::CrateId;
@@ -28,12 +28,13 @@ use crate::{
     db::HirDatabase,
     primitive::{FloatTy, IntTy},
     utils::{
-        all_super_traits, associated_type_by_name_including_super_traits, generics, make_mut_slice,
-        variant_data,
+        all_super_trait_refs, associated_type_by_name_including_super_traits, generics,
+        make_mut_slice, variant_data,
     },
     Binders, BoundVar, DebruijnIndex, FnSig, GenericPredicate, PolyFnSig, ProjectionPredicate,
-    ProjectionTy, Substs, TraitEnvironment, TraitRef, Ty, TypeCtor,
+    ProjectionTy, Substs, TraitEnvironment, TraitRef, Ty, TypeCtor, TypeWalk,
 };
+use hir_expand::name::Name;
 
 #[derive(Debug)]
 pub struct TyLoweringContext<'a> {
@@ -256,7 +257,7 @@ impl Ty {
         if remaining_segments.len() == 1 {
             // resolve unselected assoc types
             let segment = remaining_segments.first().unwrap();
-            (Ty::select_associated_type(ctx, ty, res, segment), None)
+            (Ty::select_associated_type(ctx, res, segment), None)
         } else if remaining_segments.len() > 1 {
             // FIXME report error (ambiguous associated type)
             (Ty::Unknown, None)
@@ -380,48 +381,41 @@ impl Ty {
 
     fn select_associated_type(
         ctx: &TyLoweringContext<'_>,
-        self_ty: Ty,
         res: Option<TypeNs>,
         segment: PathSegment<'_>,
     ) -> Ty {
-        let traits_from_env: Vec<_> = match res {
-            Some(TypeNs::SelfType(impl_id)) => match ctx.db.impl_trait(impl_id) {
-                None => return Ty::Unknown,
-                Some(trait_ref) => vec![trait_ref.value.trait_],
-            },
-            Some(TypeNs::GenericParam(param_id)) => {
-                let predicates = ctx.db.generic_predicates_for_param(param_id);
-                let mut traits_: Vec<_> = predicates
-                    .iter()
-                    .filter_map(|pred| match &pred.value {
-                        GenericPredicate::Implemented(tr) => Some(tr.trait_),
-                        _ => None,
-                    })
-                    .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);
+        if let Some(res) = res {
+            let ty =
+                associated_type_shorthand_candidates(ctx.db, res, move |name, t, associated_ty| {
+                    if name == segment.name {
+                        let substs = match ctx.type_param_mode {
+                            TypeParamLoweringMode::Placeholder => {
+                                // if we're lowering to placeholders, we have to put
+                                // them in now
+                                let s = Substs::type_params(
+                                    ctx.db,
+                                    ctx.resolver.generic_def().expect(
+                                        "there should be generics if there's a generic param",
+                                    ),
+                                );
+                                t.substs.clone().subst_bound_vars(&s)
+                            }
+                            TypeParamLoweringMode::Variable => t.substs.clone(),
+                        };
+                        // FIXME handle type parameters on the segment
+                        return Some(Ty::Projection(ProjectionTy {
+                            associated_ty,
+                            parameters: substs,
+                        }));
                     }
-                }
-                traits_
-            }
-            _ => return Ty::Unknown,
-        };
-        let traits = traits_from_env.into_iter().flat_map(|t| all_super_traits(ctx.db.upcast(), t));
-        for t in traits {
-            if let Some(associated_ty) = ctx.db.trait_data(t).associated_type_by_name(&segment.name)
-            {
-                let substs =
-                    Substs::build_for_def(ctx.db, t).push(self_ty).fill_with_unknown().build();
-                // FIXME handle type parameters on the segment
-                return Ty::Projection(ProjectionTy { associated_ty, parameters: substs });
-            }
+
+                    None
+                });
+
+            ty.unwrap_or(Ty::Unknown)
+        } else {
+            Ty::Unknown
         }
-        Ty::Unknown
     }
 
     fn from_hir_path_inner(
@@ -678,6 +672,61 @@ pub fn callable_item_sig(db: &dyn HirDatabase, def: CallableDef) -> PolyFnSig {
     }
 }
 
+pub fn associated_type_shorthand_candidates<R>(
+    db: &dyn HirDatabase,
+    res: TypeNs,
+    mut cb: impl FnMut(&Name, &TraitRef, TypeAliasId) -> Option<R>,
+) -> Option<R> {
+    let traits_from_env: Vec<_> = match res {
+        TypeNs::SelfType(impl_id) => match db.impl_trait(impl_id) {
+            None => vec![],
+            Some(trait_ref) => vec![trait_ref.value],
+        },
+        TypeNs::GenericParam(param_id) => {
+            let predicates = db.generic_predicates_for_param(param_id);
+            let mut traits_: Vec<_> = predicates
+                .iter()
+                .filter_map(|pred| match &pred.value {
+                    GenericPredicate::Implemented(tr) => Some(tr.clone()),
+                    _ => None,
+                })
+                .collect();
+            // Handle `Self::Type` referring to own associated type in trait definitions
+            if let GenericDefId::TraitId(trait_id) = param_id.parent {
+                let generics = generics(db.upcast(), trait_id.into());
+                if generics.params.types[param_id.local_id].provenance
+                    == TypeParamProvenance::TraitSelf
+                {
+                    let trait_ref = TraitRef {
+                        trait_: trait_id,
+                        substs: Substs::bound_vars(&generics, DebruijnIndex::INNERMOST),
+                    };
+                    traits_.push(trait_ref);
+                }
+            }
+            traits_
+        }
+        _ => vec![],
+    };
+
+    for t in traits_from_env.into_iter().flat_map(move |t| all_super_trait_refs(db, t)) {
+        let data = db.trait_data(t.trait_);
+
+        for (name, assoc_id) in &data.items {
+            match assoc_id {
+                AssocItemId::TypeAliasId(alias) => {
+                    if let Some(result) = cb(name, &t, *alias) {
+                        return Some(result);
+                    }
+                }
+                AssocItemId::FunctionId(_) | AssocItemId::ConstId(_) => {}
+            }
+        }
+    }
+
+    None
+}
+
 /// Build the type of all specific fields of a struct or enum variant.
 pub(crate) fn field_types_query(
     db: &dyn HirDatabase,
diff --git a/crates/ra_hir_ty/src/tests.rs b/crates/ra_hir_ty/src/tests.rs
index b6a96bb5c..d60732e19 100644
--- a/crates/ra_hir_ty/src/tests.rs
+++ b/crates/ra_hir_ty/src/tests.rs
@@ -361,6 +361,33 @@ fn no_such_field_with_feature_flag_diagnostics() {
 }
 
 #[test]
+fn no_such_field_enum_with_feature_flag_diagnostics() {
+    let diagnostics = TestDB::with_files(
+        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 => {},
+            }
+        }
+        "#,
+    )
+    .diagnostics()
+    .0;
+
+    assert_snapshot!(diagnostics, @r###""###);
+}
+
+#[test]
 fn no_such_field_with_feature_flag_diagnostics_on_struct_lit() {
     let diagnostics = TestDB::with_files(
         r#"
@@ -391,6 +418,38 @@ fn no_such_field_with_feature_flag_diagnostics_on_struct_lit() {
 }
 
 #[test]
+fn no_such_field_with_feature_flag_diagnostics_on_block_expr() {
+    let diagnostics = TestDB::with_files(
+        r#"
+        //- /lib.rs crate:foo cfg:feature=foo
+        struct S {
+            #[cfg(feature = "foo")]
+            foo: u32,
+            #[cfg(not(feature = "foo"))]
+            bar: u32,
+        }
+
+        impl S {
+            fn new(bar: u32) -> Self {
+                #[cfg(feature = "foo")]
+                {
+                Self { foo: bar }
+                }
+                #[cfg(not(feature = "foo"))]
+                {
+                Self { bar }
+                }
+            }
+        }
+        "#,
+    )
+    .diagnostics()
+    .0;
+
+    assert_snapshot!(diagnostics, @r###""###);
+}
+
+#[test]
 fn no_such_field_with_feature_flag_diagnostics_on_struct_fields() {
     let diagnostics = TestDB::with_files(
         r#"
diff --git a/crates/ra_hir_ty/src/tests/macros.rs b/crates/ra_hir_ty/src/tests/macros.rs
index 6b5267232..07398ddcc 100644
--- a/crates/ra_hir_ty/src/tests/macros.rs
+++ b/crates/ra_hir_ty/src/tests/macros.rs
@@ -269,7 +269,7 @@ fn test() { S.foo()<|>; }
 }
 
 #[test]
-fn infer_impl_items_generated_by_macros() {
+fn infer_assoc_items_generated_by_macros() {
     let t = type_at(
         r#"
 //- /main.rs
@@ -288,7 +288,7 @@ fn test() { S.foo()<|>; }
 }
 
 #[test]
-fn infer_impl_items_generated_by_macros_chain() {
+fn infer_assoc_items_generated_by_macros_chain() {
     let t = type_at(
         r#"
 //- /main.rs
@@ -339,6 +339,46 @@ pub fn baz() -> usize { 31usize }
 }
 
 #[test]
+fn infer_macro_with_dollar_crate_is_correct_in_trait_associate_type() {
+    let (db, pos) = TestDB::with_position(
+        r#"
+//- /main.rs crate:main deps:foo
+use foo::Trait;
+
+fn test() {
+    let msg = foo::Message(foo::MessageRef);
+    let r = msg.deref();
+    r<|>;
+}
+
+//- /lib.rs crate:foo
+pub struct MessageRef;
+pub struct Message(MessageRef);
+
+pub trait Trait {
+    type Target;
+    fn deref(&self) -> &Self::Target;
+}
+
+#[macro_export]
+macro_rules! expand {
+    () => {
+        impl Trait for Message {
+            type Target = $crate::MessageRef;
+            fn deref(&self) ->  &Self::Target {
+                &self.0
+            }
+        }
+    }
+}
+
+expand!();
+"#,
+    );
+    assert_eq!("&MessageRef", type_at_pos(&db, pos));
+}
+
+#[test]
 fn infer_type_value_non_legacy_macro_use_as() {
     assert_snapshot!(
         infer(r#"
@@ -388,6 +428,32 @@ fn main() {
 }
 
 #[test]
+fn infer_local_inner_macros() {
+    let (db, pos) = TestDB::with_position(
+        r#"
+//- /main.rs crate:main deps:foo
+fn test() {
+    let x = foo::foo!(1);
+    x<|>;
+}
+
+//- /lib.rs crate:foo
+#[macro_export(local_inner_macros)]
+macro_rules! foo {
+    (1) => { bar!() };
+}
+
+#[macro_export]
+macro_rules! bar {
+    () => { 42 }
+}
+
+"#,
+    );
+    assert_eq!("i32", type_at_pos(&db, pos));
+}
+
+#[test]
 fn infer_builtin_macros_line() {
     assert_snapshot!(
         infer(r#"
@@ -622,14 +688,31 @@ fn main() {
 fn infer_derive_clone_simple() {
     let (db, pos) = TestDB::with_position(
         r#"
-//- /main.rs crate:main deps:std
+//- /main.rs crate:main deps:core
 #[derive(Clone)]
 struct S;
 fn test() {
     S.clone()<|>;
 }
 
-//- /lib.rs crate:std
+//- /lib.rs crate:core
+#[prelude_import]
+use clone::*;
+mod clone {
+    trait Clone {
+        fn clone(&self) -> Self;
+    }
+}
+"#,
+    );
+    assert_eq!("S", type_at_pos(&db, pos));
+}
+
+#[test]
+fn infer_derive_clone_in_core() {
+    let (db, pos) = TestDB::with_position(
+        r#"
+//- /lib.rs crate:core
 #[prelude_import]
 use clone::*;
 mod clone {
@@ -637,6 +720,14 @@ mod clone {
         fn clone(&self) -> Self;
     }
 }
+#[derive(Clone)]
+pub struct S;
+
+//- /main.rs crate:main deps:core
+use core::S;
+fn test() {
+    S.clone()<|>;
+}
 "#,
     );
     assert_eq!("S", type_at_pos(&db, pos));
@@ -646,7 +737,7 @@ mod clone {
 fn infer_derive_clone_with_params() {
     let (db, pos) = TestDB::with_position(
         r#"
-//- /main.rs crate:main deps:std
+//- /main.rs crate:main deps:core
 #[derive(Clone)]
 struct S;
 #[derive(Clone)]
@@ -656,7 +747,7 @@ fn test() {
     (Wrapper(S).clone(), Wrapper(NonClone).clone())<|>;
 }
 
-//- /lib.rs crate:std
+//- /lib.rs crate:core
 #[prelude_import]
 use clone::*;
 mod clone {
diff --git a/crates/ra_hir_ty/src/tests/regression.rs b/crates/ra_hir_ty/src/tests/regression.rs
index 8a1292c7a..115ad8328 100644
--- a/crates/ra_hir_ty/src/tests/regression.rs
+++ b/crates/ra_hir_ty/src/tests/regression.rs
@@ -535,6 +535,35 @@ fn foo(b: Bar) {
 }
 
 #[test]
+fn issue_4235_name_conflicts() {
+    assert_snapshot!(
+        infer(r#"
+struct FOO {}
+static FOO:FOO = FOO {};
+
+impl FOO {
+    fn foo(&self) {}
+}
+
+fn main() {
+    let a = &FOO;
+    a.foo();
+}
+"#), @r###"
+    32..38 'FOO {}': FOO
+    64..68 'self': &FOO
+    70..72 '{}': ()
+    86..120 '{     ...o(); }': ()
+    96..97 'a': &FOO
+    100..104 '&FOO': &FOO
+    101..104 'FOO': FOO
+    110..111 'a': &FOO
+    110..117 'a.foo()': ()
+"###
+    );
+}
+
+#[test]
 fn issue_4053_diesel_where_clauses() {
     assert_snapshot!(
         infer(r#"
diff --git a/crates/ra_hir_ty/src/tests/simple.rs b/crates/ra_hir_ty/src/tests/simple.rs
index 56abc65b8..3d3088965 100644
--- a/crates/ra_hir_ty/src/tests/simple.rs
+++ b/crates/ra_hir_ty/src/tests/simple.rs
@@ -1755,3 +1755,35 @@ fn main() {
     "###
     );
 }
+
+#[test]
+fn effects_smoke_test() {
+    assert_snapshot!(
+        infer(r#"
+fn main() {
+    let x = unsafe { 92 };
+    let y = async { async { () }.await };
+    let z = try { () };
+    let t = 'a: { 92 };
+}
+"#),
+        @r###"
+    11..131 '{     ...2 }; }': ()
+    21..22 'x': i32
+    32..38 '{ 92 }': i32
+    34..36 '92': i32
+    48..49 'y': {unknown}
+    58..80 '{ asyn...wait }': {unknown}
+    60..78 'async ....await': {unknown}
+    66..72 '{ () }': ()
+    68..70 '()': ()
+    90..91 'z': {unknown}
+    94..104 'try { () }': {unknown}
+    98..104 '{ () }': ()
+    100..102 '()': ()
+    114..115 't': i32
+    122..128 '{ 92 }': i32
+    124..126 '92': i32
+    "###
+    )
+}
diff --git a/crates/ra_hir_ty/src/tests/traits.rs b/crates/ra_hir_ty/src/tests/traits.rs
index f51cdd496..9d32cbc7a 100644
--- a/crates/ra_hir_ty/src/tests/traits.rs
+++ b/crates/ra_hir_ty/src/tests/traits.rs
@@ -1898,6 +1898,36 @@ fn test() {
 }
 
 #[test]
+fn unselected_projection_chalk_fold() {
+    let t = type_at(
+        r#"
+//- /main.rs
+trait Interner {}
+trait Fold<I: Interner, TI = I> {
+    type Result;
+}
+
+struct Ty<I: Interner> {}
+impl<I: Interner, TI: Interner> Fold<I, TI> for Ty<I> {
+    type Result = Ty<TI>;
+}
+
+fn fold<I: Interner, T>(interner: &I, t: T) -> T::Result
+where
+    T: Fold<I, I>,
+{
+    loop {}
+}
+
+fn foo<I: Interner>(interner: &I, t: Ty<I>) {
+    fold(interner, t)<|>;
+}
+"#,
+    );
+    assert_eq!(t, "Ty<I>");
+}
+
+#[test]
 fn trait_impl_self_ty() {
     let t = type_at(
         r#"
@@ -2025,7 +2055,7 @@ fn test<I: Iterator<Item: Iterator<Item = u32>>>() {
 #[test]
 fn proc_macro_server_types() {
     assert_snapshot!(
-        infer_with_mismatches(r#"
+        infer(r#"
 macro_rules! with_api {
     ($S:ident, $self:ident, $m:ident) => {
         $m! {
@@ -2039,9 +2069,9 @@ macro_rules! with_api {
 }
 macro_rules! associated_item {
     (type TokenStream) =>
-        (type TokenStream: 'static + Clone;);
+        (type TokenStream: 'static;);
     (type Group) =>
-        (type Group: 'static + Clone;);
+        (type Group: 'static;);
     ($($item:tt)*) => ($($item)*;)
 }
 macro_rules! declare_server_traits {
@@ -2053,21 +2083,23 @@ macro_rules! declare_server_traits {
         }
 
         $(pub trait $name: Types {
-            $(associated_item!(fn $method(&mut self, $($arg: $arg_ty),*) $(-> $ret_ty)?);)*
+            $(associated_item!(fn $method($($arg: $arg_ty),*) $(-> $ret_ty)?);)*
         })*
 
         pub trait Server: Types $(+ $name)* {}
         impl<S: Types $(+ $name)*> Server for S {}
     }
 }
+
 with_api!(Self, self_, declare_server_traits);
-struct Group {}
-struct TokenStream {}
+struct G {}
+struct T {}
 struct Rustc;
 impl Types for Rustc {
-    type TokenStream = TokenStream;
-    type Group = Group;
+    type TokenStream = T;
+    type Group = G;
 }
+
 fn make<T>() -> T { loop {} }
 impl TokenStream for Rustc {
     fn new() -> Self::TokenStream {
@@ -2075,17 +2107,17 @@ impl TokenStream for Rustc {
         make()
     }
 }
-"#, true),
+"#),
         @r###"
-    1115..1126 '{ loop {} }': T
-    1117..1124 'loop {}': !
-    1122..1124 '{}': ()
-    1190..1253 '{     ...     }': {unknown}
-    1204..1209 'group': {unknown}
-    1225..1229 'make': fn make<{unknown}>() -> {unknown}
-    1225..1231 'make()': {unknown}
-    1241..1245 'make': fn make<{unknown}>() -> {unknown}
-    1241..1247 'make()': {unknown}
+    1062..1073 '{ loop {} }': T
+    1064..1071 'loop {}': !
+    1069..1071 '{}': ()
+    1137..1200 '{     ...     }': T
+    1151..1156 'group': G
+    1172..1176 'make': fn make<G>() -> G
+    1172..1178 'make()': G
+    1188..1192 'make': fn make<T>() -> T
+    1188..1194 'make()': T
     "###
     );
 }
diff --git a/crates/ra_hir_ty/src/utils.rs b/crates/ra_hir_ty/src/utils.rs
index 1e5022fa4..f98350bf9 100644
--- a/crates/ra_hir_ty/src/utils.rs
+++ b/crates/ra_hir_ty/src/utils.rs
@@ -14,6 +14,8 @@ use hir_def::{
 };
 use hir_expand::name::{name, Name};
 
+use crate::{db::HirDatabase, GenericPredicate, TraitRef};
+
 fn direct_super_traits(db: &dyn DefDatabase, trait_: TraitId) -> Vec<TraitId> {
     let resolver = trait_.resolver(db);
     // returning the iterator directly doesn't easily work because of
@@ -41,6 +43,28 @@ fn direct_super_traits(db: &dyn DefDatabase, trait_: TraitId) -> Vec<TraitId> {
         .collect()
 }
 
+fn direct_super_trait_refs(db: &dyn HirDatabase, trait_ref: &TraitRef) -> Vec<TraitRef> {
+    // returning the iterator directly doesn't easily work because of
+    // lifetime problems, but since there usually shouldn't be more than a
+    // few direct traits this should be fine (we could even use some kind of
+    // SmallVec if performance is a concern)
+    let generic_params = db.generic_params(trait_ref.trait_.into());
+    let trait_self = match generic_params.find_trait_self_param() {
+        Some(p) => TypeParamId { parent: trait_ref.trait_.into(), local_id: p },
+        None => return Vec::new(),
+    };
+    db.generic_predicates_for_param(trait_self)
+        .iter()
+        .filter_map(|pred| {
+            pred.as_ref().filter_map(|pred| match pred {
+                GenericPredicate::Implemented(tr) => Some(tr.clone()),
+                _ => None,
+            })
+        })
+        .map(|pred| pred.subst(&trait_ref.substs))
+        .collect()
+}
+
 /// Returns an iterator over the whole super trait hierarchy (including the
 /// trait itself).
 pub(super) fn all_super_traits(db: &dyn DefDatabase, trait_: TraitId) -> Vec<TraitId> {
@@ -62,6 +86,30 @@ pub(super) fn all_super_traits(db: &dyn DefDatabase, trait_: TraitId) -> Vec<Tra
     result
 }
 
+/// Given a trait ref (`Self: Trait`), builds all the implied trait refs for
+/// super traits. The original trait ref will be included. So the difference to
+/// `all_super_traits` is that we keep track of type parameters; for example if
+/// we have `Self: Trait<u32, i32>` and `Trait<T, U>: OtherTrait<U>` we'll get
+/// `Self: OtherTrait<i32>`.
+pub(super) fn all_super_trait_refs(db: &dyn HirDatabase, trait_ref: TraitRef) -> Vec<TraitRef> {
+    // we need to take care a bit here to avoid infinite loops in case of cycles
+    // (i.e. if we have `trait A: B; trait B: A;`)
+    let mut result = vec![trait_ref];
+    let mut i = 0;
+    while i < result.len() {
+        let t = &result[i];
+        // yeah this is quadratic, but trait hierarchies should be flat
+        // enough that this doesn't matter
+        for tt in direct_super_trait_refs(db, t) {
+            if !result.iter().any(|tr| tr.trait_ == tt.trait_) {
+                result.push(tt);
+            }
+        }
+        i += 1;
+    }
+    result
+}
+
 /// Finds a path from a trait to one of its super traits. Returns an empty
 /// vector if there is no path.
 pub(super) fn find_super_trait_path(