4 files changed, 246 insertions, 14 deletions

diff --git a/crates/ra_hir/src/ty/lower.rs b/crates/ra_hir/src/ty/lower.rs
index debedcbb8..47d161277 100644
--- a/crates/ra_hir/src/ty/lower.rs
+++ b/crates/ra_hir/src/ty/lower.rs
@@ -17,7 +17,7 @@ use crate::{
     path::{GenericArg, PathSegment},
     resolve::{Resolution, Resolver},
     ty::AdtDef,
-    type_ref::TypeRef,
+    type_ref::{TypeBound, TypeRef},
     BuiltinType, Const, Enum, EnumVariant, Function, HirDatabase, ModuleDef, Path, Static, Struct,
     StructField, Trait, TypeAlias, Union,
 };
@@ -58,6 +58,22 @@ impl Ty {
                 let sig = Substs(inner_tys.into());
                 Ty::apply(TypeCtor::FnPtr { num_args: sig.len() as u16 - 1 }, sig)
             }
+            TypeRef::DynTrait(bounds) => {
+                let self_ty = Ty::Bound(0);
+                let predicates = bounds
+                    .iter()
+                    .map(|b| GenericPredicate::from_type_bound(db, resolver, b, self_ty.clone()))
+                    .collect::<Vec<_>>();
+                Ty::Dyn(predicates.into())
+            }
+            TypeRef::ImplTrait(bounds) => {
+                let self_ty = Ty::Bound(0);
+                let predicates = bounds
+                    .iter()
+                    .map(|b| GenericPredicate::from_type_bound(db, resolver, b, self_ty.clone()))
+                    .collect::<Vec<_>>();
+                Ty::Opaque(predicates.into())
+            }
             TypeRef::Error => Ty::Unknown,
         }
     }
@@ -310,13 +326,46 @@ impl TraitRef {
         TraitRef { trait_, substs }
     }
 
-    pub(crate) fn for_where_predicate(
+    pub(crate) fn from_where_predicate(
         db: &impl HirDatabase,
         resolver: &Resolver,
         pred: &WherePredicate,
     ) -> Option<TraitRef> {
         let self_ty = Ty::from_hir(db, resolver, &pred.type_ref);
-        TraitRef::from_path(db, resolver, &pred.trait_ref, Some(self_ty))
+        TraitRef::from_type_bound(db, resolver, &pred.bound, self_ty)
+    }
+
+    pub(crate) fn from_type_bound(
+        db: &impl HirDatabase,
+        resolver: &Resolver,
+        bound: &TypeBound,
+        self_ty: Ty,
+    ) -> Option<TraitRef> {
+        match bound {
+            TypeBound::Path(path) => TraitRef::from_path(db, resolver, path, Some(self_ty)),
+            TypeBound::Error => None,
+        }
+    }
+}
+
+impl GenericPredicate {
+    pub(crate) fn from_where_predicate(
+        db: &impl HirDatabase,
+        resolver: &Resolver,
+        where_predicate: &WherePredicate,
+    ) -> GenericPredicate {
+        TraitRef::from_where_predicate(db, &resolver, where_predicate)
+            .map_or(GenericPredicate::Error, GenericPredicate::Implemented)
+    }
+
+    pub(crate) fn from_type_bound(
+        db: &impl HirDatabase,
+        resolver: &Resolver,
+        bound: &TypeBound,
+        self_ty: Ty,
+    ) -> GenericPredicate {
+        TraitRef::from_type_bound(db, &resolver, bound, self_ty)
+            .map_or(GenericPredicate::Error, GenericPredicate::Implemented)
     }
 }
 
@@ -376,10 +425,7 @@ pub(crate) fn trait_env(
 ) -> Arc<super::TraitEnvironment> {
     let predicates = resolver
         .where_predicates_in_scope()
-        .map(|pred| {
-            TraitRef::for_where_predicate(db, &resolver, pred)
-                .map_or(GenericPredicate::Error, GenericPredicate::Implemented)
-        })
+        .map(|pred| GenericPredicate::from_where_predicate(db, &resolver, pred))
         .collect::<Vec<_>>();
 
     Arc::new(super::TraitEnvironment { predicates })
@@ -393,10 +439,7 @@ pub(crate) fn generic_predicates_query(
     let resolver = def.resolver(db);
     let predicates = resolver
         .where_predicates_in_scope()
-        .map(|pred| {
-            TraitRef::for_where_predicate(db, &resolver, pred)
-                .map_or(GenericPredicate::Error, GenericPredicate::Implemented)
-        })
+        .map(|pred| GenericPredicate::from_where_predicate(db, &resolver, pred))
         .collect::<Vec<_>>();
     predicates.into()
 }
diff --git a/crates/ra_hir/src/ty/method_resolution.rs b/crates/ra_hir/src/ty/method_resolution.rs
index 3f4c43aee..9873a0440 100644
--- a/crates/ra_hir/src/ty/method_resolution.rs
+++ b/crates/ra_hir/src/ty/method_resolution.rs
@@ -211,12 +211,19 @@ fn iterate_trait_method_candidates<T>(
     let krate = resolver.krate()?;
     // FIXME: maybe put the trait_env behind a query (need to figure out good input parameters for that)
     let env = lower::trait_env(db, resolver);
-    'traits: for t in resolver.traits_in_scope(db) {
+    // if ty is `impl Trait` or `dyn Trait`, the trait doesn't need to be in scope
+    let traits = ty.value.inherent_trait().into_iter().chain(resolver.traits_in_scope(db));
+    'traits: for t in traits {
         let data = t.trait_data(db);
+
+        // FIXME this is a bit of a hack, since Chalk should say the same thing
+        // anyway, but currently Chalk doesn't implement `dyn/impl Trait` yet
+        let inherently_implemented = ty.value.inherent_trait() == Some(t);
+
         // we'll be lazy about checking whether the type implements the
         // trait, but if we find out it doesn't, we'll skip the rest of the
         // iteration
-        let mut known_implemented = false;
+        let mut known_implemented = inherently_implemented;
         for item in data.items() {
             if let TraitItem::Function(m) = *item {
                 let data = m.data(db);
@@ -271,6 +278,11 @@ pub(crate) fn implements_trait(
     krate: Crate,
     trait_: Trait,
 ) -> bool {
+    if ty.value.inherent_trait() == Some(trait_) {
+        // FIXME this is a bit of a hack, since Chalk should say the same thing
+        // anyway, but currently Chalk doesn't implement `dyn/impl Trait` yet
+        return true;
+    }
     let env = lower::trait_env(db, resolver);
     let goal = generic_implements_goal(db, env.clone(), trait_, ty.clone());
     let solution = db.trait_solve(krate, goal);
diff --git a/crates/ra_hir/src/ty/tests.rs b/crates/ra_hir/src/ty/tests.rs
index 57fd5492d..c5818b738 100644
--- a/crates/ra_hir/src/ty/tests.rs
+++ b/crates/ra_hir/src/ty/tests.rs
@@ -3273,6 +3273,181 @@ fn test<T: ApplyL>(t: T) {
     assert_eq!(t, "{unknown}");
 }
 
+#[test]
+fn impl_trait() {
+    assert_snapshot_matches!(
+        infer(r#"
+trait Trait<T> {
+    fn foo(&self) -> T;
+    fn foo2(&self) -> i64;
+}
+fn bar() -> impl Trait<u64> {}
+
+fn test(x: impl Trait<u64>, y: &impl Trait<u64>) {
+    x;
+    y;
+    let z = bar();
+    x.foo();
+    y.foo();
+    z.foo();
+    x.foo2();
+    y.foo2();
+    z.foo2();
+}
+"#),
+        @r###"
+   ⋮
+   ⋮[30; 34) 'self': &Self
+   ⋮[55; 59) 'self': &Self
+   ⋮[99; 101) '{}': ()
+   ⋮[111; 112) 'x': impl Trait<u64>
+   ⋮[131; 132) 'y': &impl Trait<u64>
+   ⋮[152; 269) '{     ...2(); }': ()
+   ⋮[158; 159) 'x': impl Trait<u64>
+   ⋮[165; 166) 'y': &impl Trait<u64>
+   ⋮[176; 177) 'z': impl Trait<u64>
+   ⋮[180; 183) 'bar': fn bar() -> impl Trait<u64>
+   ⋮[180; 185) 'bar()': impl Trait<u64>
+   ⋮[191; 192) 'x': impl Trait<u64>
+   ⋮[191; 198) 'x.foo()': {unknown}
+   ⋮[204; 205) 'y': &impl Trait<u64>
+   ⋮[204; 211) 'y.foo()': {unknown}
+   ⋮[217; 218) 'z': impl Trait<u64>
+   ⋮[217; 224) 'z.foo()': {unknown}
+   ⋮[230; 231) 'x': impl Trait<u64>
+   ⋮[230; 238) 'x.foo2()': i64
+   ⋮[244; 245) 'y': &impl Trait<u64>
+   ⋮[244; 252) 'y.foo2()': i64
+   ⋮[258; 259) 'z': impl Trait<u64>
+   ⋮[258; 266) 'z.foo2()': i64
+    "###
+    );
+}
+
+#[test]
+fn dyn_trait() {
+    assert_snapshot_matches!(
+        infer(r#"
+trait Trait<T> {
+    fn foo(&self) -> T;
+    fn foo2(&self) -> i64;
+}
+fn bar() -> dyn Trait<u64> {}
+
+fn test(x: dyn Trait<u64>, y: &dyn Trait<u64>) {
+    x;
+    y;
+    let z = bar();
+    x.foo();
+    y.foo();
+    z.foo();
+    x.foo2();
+    y.foo2();
+    z.foo2();
+}
+"#),
+        @r###"
+   ⋮
+   ⋮[30; 34) 'self': &Self
+   ⋮[55; 59) 'self': &Self
+   ⋮[98; 100) '{}': ()
+   ⋮[110; 111) 'x': dyn Trait<u64>
+   ⋮[129; 130) 'y': &dyn Trait<u64>
+   ⋮[149; 266) '{     ...2(); }': ()
+   ⋮[155; 156) 'x': dyn Trait<u64>
+   ⋮[162; 163) 'y': &dyn Trait<u64>
+   ⋮[173; 174) 'z': dyn Trait<u64>
+   ⋮[177; 180) 'bar': fn bar() -> dyn Trait<u64>
+   ⋮[177; 182) 'bar()': dyn Trait<u64>
+   ⋮[188; 189) 'x': dyn Trait<u64>
+   ⋮[188; 195) 'x.foo()': {unknown}
+   ⋮[201; 202) 'y': &dyn Trait<u64>
+   ⋮[201; 208) 'y.foo()': {unknown}
+   ⋮[214; 215) 'z': dyn Trait<u64>
+   ⋮[214; 221) 'z.foo()': {unknown}
+   ⋮[227; 228) 'x': dyn Trait<u64>
+   ⋮[227; 235) 'x.foo2()': i64
+   ⋮[241; 242) 'y': &dyn Trait<u64>
+   ⋮[241; 249) 'y.foo2()': i64
+   ⋮[255; 256) 'z': dyn Trait<u64>
+   ⋮[255; 263) 'z.foo2()': i64
+    "###
+    );
+}
+
+#[test]
+fn dyn_trait_bare() {
+    assert_snapshot_matches!(
+        infer(r#"
+trait Trait {
+    fn foo(&self) -> u64;
+}
+fn bar() -> Trait {}
+
+fn test(x: Trait, y: &Trait) -> u64 {
+    x;
+    y;
+    let z = bar();
+    x.foo();
+    y.foo();
+    z.foo();
+}
+"#),
+        @r###"
+   ⋮
+   ⋮[27; 31) 'self': &Self
+   ⋮[61; 63) '{}': ()
+   ⋮[73; 74) 'x': {unknown}
+   ⋮[83; 84) 'y': &{unknown}
+   ⋮[101; 176) '{     ...o(); }': ()
+   ⋮[107; 108) 'x': {unknown}
+   ⋮[114; 115) 'y': &{unknown}
+   ⋮[125; 126) 'z': {unknown}
+   ⋮[129; 132) 'bar': fn bar() -> {unknown}
+   ⋮[129; 134) 'bar()': {unknown}
+   ⋮[140; 141) 'x': {unknown}
+   ⋮[140; 147) 'x.foo()': {unknown}
+   ⋮[153; 154) 'y': &{unknown}
+   ⋮[153; 160) 'y.foo()': {unknown}
+   ⋮[166; 167) 'z': {unknown}
+   ⋮[166; 173) 'z.foo()': {unknown}
+    "###
+    );
+}
+
+#[test]
+fn weird_bounds() {
+    assert_snapshot_matches!(
+        infer(r#"
+trait Trait {}
+fn test() {
+    let a: impl Trait + 'lifetime = foo;
+    let b: impl 'lifetime = foo;
+    let b: impl (Trait) = foo;
+    let b: impl ('lifetime) = foo;
+    let d: impl ?Sized = foo;
+    let e: impl Trait + ?Sized = foo;
+}
+"#),
+        @r###"
+   ⋮
+   ⋮[26; 237) '{     ...foo; }': ()
+   ⋮[36; 37) 'a': impl Trait + {error}
+   ⋮[64; 67) 'foo': impl Trait + {error}
+   ⋮[77; 78) 'b': impl {error}
+   ⋮[97; 100) 'foo': impl {error}
+   ⋮[110; 111) 'b': impl Trait
+   ⋮[128; 131) 'foo': impl Trait
+   ⋮[141; 142) 'b': impl {error}
+   ⋮[163; 166) 'foo': impl {error}
+   ⋮[176; 177) 'd': impl {error}
+   ⋮[193; 196) 'foo': impl {error}
+   ⋮[206; 207) 'e': impl Trait + {error}
+   ⋮[231; 234) 'foo': impl Trait + {error}
+    "###
+    );
+}
+
 fn type_at_pos(db: &MockDatabase, pos: FilePosition) -> String {
     let file = db.parse(pos.file_id).ok().unwrap();
     let expr = algo::find_node_at_offset::<ast::Expr>(file.syntax(), pos.offset).unwrap();
diff --git a/crates/ra_hir/src/ty/traits/chalk.rs b/crates/ra_hir/src/ty/traits/chalk.rs
index 6df7094c5..2ebc06135 100644
--- a/crates/ra_hir/src/ty/traits/chalk.rs
+++ b/crates/ra_hir/src/ty/traits/chalk.rs
@@ -80,7 +80,9 @@ impl ToChalk for Ty {
             // FIXME this is clearly incorrect, but probably not too incorrect
             // and I'm not sure what to actually do with Ty::Unknown
             // maybe an alternative would be `for<T> T`? (meaningless in rust, but expressible in chalk's Ty)
-            Ty::Unknown => {
+            //
+            // FIXME also dyn and impl Trait are currently handled like Unknown because Chalk doesn't have them yet
+            Ty::Unknown | Ty::Dyn(_) | Ty::Opaque(_) => {
                 PlaceholderIndex { ui: UniverseIndex::ROOT, idx: usize::max_value() }.to_ty()
             }
         }