6 files changed, 291 insertions, 8 deletions

diff --git a/crates/ra_hir_ty/src/diagnostics.rs b/crates/ra_hir_ty/src/diagnostics.rs
index 927896d6f..c8fd54861 100644
--- a/crates/ra_hir_ty/src/diagnostics.rs
+++ b/crates/ra_hir_ty/src/diagnostics.rs
@@ -21,7 +21,7 @@ impl Diagnostic for NoSuchField {
     }
 
     fn source(&self) -> InFile<SyntaxNodePtr> {
-        InFile { file_id: self.file, value: self.field.clone().into() }
+        InFile::new(self.file, self.field.clone().into())
     }
 
     fn as_any(&self) -> &(dyn Any + Send + 'static) {
diff --git a/crates/ra_hir_ty/src/infer.rs b/crates/ra_hir_ty/src/infer.rs
index 246b0e9be..b6d9b3438 100644
--- a/crates/ra_hir_ty/src/infer.rs
+++ b/crates/ra_hir_ty/src/infer.rs
@@ -682,10 +682,10 @@ mod diagnostics {
         ) {
             match self {
                 InferenceDiagnostic::NoSuchField { expr, field } => {
-                    let file = owner.lookup(db.upcast()).source(db.upcast()).file_id;
+                    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, field })
+                    sink.push(NoSuchField { file: source.file_id, field: field.value })
                 }
             }
         }
diff --git a/crates/ra_hir_ty/src/infer/coerce.rs b/crates/ra_hir_ty/src/infer/coerce.rs
index 959b1e212..89200255a 100644
--- a/crates/ra_hir_ty/src/infer/coerce.rs
+++ b/crates/ra_hir_ty/src/infer/coerce.rs
@@ -51,7 +51,7 @@ impl<'a> InferenceContext<'a> {
             // Trivial cases, this should go after `never` check to
             // avoid infer result type to be never
             _ => {
-                if self.table.unify_inner_trivial(&from_ty, &to_ty) {
+                if self.table.unify_inner_trivial(&from_ty, &to_ty, 0) {
                     return true;
                 }
             }
@@ -175,7 +175,7 @@ impl<'a> InferenceContext<'a> {
                     return self.table.unify_substs(st1, st2, 0);
                 }
                 _ => {
-                    if self.table.unify_inner_trivial(&derefed_ty, &to_ty) {
+                    if self.table.unify_inner_trivial(&derefed_ty, &to_ty, 0) {
                         return true;
                     }
                 }
diff --git a/crates/ra_hir_ty/src/infer/unify.rs b/crates/ra_hir_ty/src/infer/unify.rs
index 5f6cea8d3..ab0bc8b70 100644
--- a/crates/ra_hir_ty/src/infer/unify.rs
+++ b/crates/ra_hir_ty/src/infer/unify.rs
@@ -8,7 +8,8 @@ use test_utils::tested_by;
 
 use super::{InferenceContext, Obligation};
 use crate::{
-    BoundVar, Canonical, DebruijnIndex, InEnvironment, InferTy, Substs, Ty, TypeCtor, TypeWalk,
+    BoundVar, Canonical, DebruijnIndex, GenericPredicate, InEnvironment, InferTy, Substs, Ty,
+    TypeCtor, TypeWalk,
 };
 
 impl<'a> InferenceContext<'a> {
@@ -226,16 +227,26 @@ impl InferenceTable {
             (Ty::Apply(a_ty1), Ty::Apply(a_ty2)) if a_ty1.ctor == a_ty2.ctor => {
                 self.unify_substs(&a_ty1.parameters, &a_ty2.parameters, depth + 1)
             }
-            _ => self.unify_inner_trivial(&ty1, &ty2),
+
+            _ => self.unify_inner_trivial(&ty1, &ty2, depth),
         }
     }
 
-    pub(super) fn unify_inner_trivial(&mut self, ty1: &Ty, ty2: &Ty) -> bool {
+    pub(super) fn unify_inner_trivial(&mut self, ty1: &Ty, ty2: &Ty, depth: usize) -> bool {
         match (ty1, ty2) {
             (Ty::Unknown, _) | (_, Ty::Unknown) => true,
 
             (Ty::Placeholder(p1), Ty::Placeholder(p2)) if *p1 == *p2 => true,
 
+            (Ty::Dyn(dyn1), Ty::Dyn(dyn2)) if dyn1.len() == dyn2.len() => {
+                for (pred1, pred2) in dyn1.iter().zip(dyn2.iter()) {
+                    if !self.unify_preds(pred1, pred2, depth + 1) {
+                        return false;
+                    }
+                }
+                true
+            }
+
             (Ty::Infer(InferTy::TypeVar(tv1)), Ty::Infer(InferTy::TypeVar(tv2)))
             | (Ty::Infer(InferTy::IntVar(tv1)), Ty::Infer(InferTy::IntVar(tv2)))
             | (Ty::Infer(InferTy::FloatVar(tv1)), Ty::Infer(InferTy::FloatVar(tv2)))
@@ -268,6 +279,31 @@ impl InferenceTable {
         }
     }
 
+    fn unify_preds(
+        &mut self,
+        pred1: &GenericPredicate,
+        pred2: &GenericPredicate,
+        depth: usize,
+    ) -> bool {
+        match (pred1, pred2) {
+            (GenericPredicate::Implemented(tr1), GenericPredicate::Implemented(tr2))
+                if tr1.trait_ == tr2.trait_ =>
+            {
+                self.unify_substs(&tr1.substs, &tr2.substs, depth + 1)
+            }
+            (GenericPredicate::Projection(proj1), GenericPredicate::Projection(proj2))
+                if proj1.projection_ty.associated_ty == proj2.projection_ty.associated_ty =>
+            {
+                self.unify_substs(
+                    &proj1.projection_ty.parameters,
+                    &proj2.projection_ty.parameters,
+                    depth + 1,
+                ) && self.unify_inner(&proj1.ty, &proj2.ty, depth + 1)
+            }
+            _ => false,
+        }
+    }
+
     /// If `ty` is a type variable with known type, returns that type;
     /// otherwise, return ty.
     pub fn resolve_ty_shallow<'b>(&mut self, ty: &'b Ty) -> Cow<'b, Ty> {
diff --git a/crates/ra_hir_ty/src/tests/regression.rs b/crates/ra_hir_ty/src/tests/regression.rs
index d69115a2f..61284d672 100644
--- a/crates/ra_hir_ty/src/tests/regression.rs
+++ b/crates/ra_hir_ty/src/tests/regression.rs
@@ -484,3 +484,52 @@ fn main() {
 
     assert_eq!("()", super::type_at_pos(&db, pos));
 }
+
+#[test]
+fn issue_3999_slice() {
+    assert_snapshot!(
+        infer(r#"
+fn foo(params: &[usize]) {
+    match params {
+        [ps @ .., _] => {}
+    }
+}
+"#),
+        @r###"
+    [8; 14) 'params': &[usize]
+    [26; 81) '{     ...   } }': ()
+    [32; 79) 'match ...     }': ()
+    [38; 44) 'params': &[usize]
+    [55; 67) '[ps @ .., _]': [usize]
+    [65; 66) '_': usize
+    [71; 73) '{}': ()
+    "###
+    );
+}
+
+#[test]
+fn issue_3999_struct() {
+    // rust-analyzer should not panic on seeing this malformed
+    // record pattern.
+    assert_snapshot!(
+        infer(r#"
+struct Bar {
+    a: bool,
+}
+fn foo(b: Bar) {
+    match b {
+        Bar { a: .. } => {},
+    }
+}
+"#),
+        @r###"
+    [36; 37) 'b': Bar
+    [44; 96) '{     ...   } }': ()
+    [50; 94) 'match ...     }': ()
+    [56; 57) 'b': Bar
+    [68; 81) 'Bar { a: .. }': Bar
+    [77; 79) '..': bool
+    [85; 87) '{}': ()
+    "###
+    );
+}
diff --git a/crates/ra_hir_ty/src/tests/traits.rs b/crates/ra_hir_ty/src/tests/traits.rs
index 36f53b264..a46f03b7f 100644
--- a/crates/ra_hir_ty/src/tests/traits.rs
+++ b/crates/ra_hir_ty/src/tests/traits.rs
@@ -2240,3 +2240,201 @@ fn test(x: Box<dyn Trait>) {
     );
     assert_eq!(t, "()");
 }
+
+#[test]
+fn string_to_owned() {
+    let t = type_at(
+        r#"
+//- /main.rs
+struct String {}
+pub trait ToOwned {
+    type Owned;
+    fn to_owned(&self) -> Self::Owned;
+}
+impl ToOwned for str {
+    type Owned = String;
+}
+fn test() {
+    "foo".to_owned()<|>;
+}
+"#,
+    );
+    assert_eq!(t, "String");
+}
+
+#[test]
+fn iterator_chain() {
+    assert_snapshot!(
+        infer(r#"
+//- /main.rs
+#[lang = "fn_once"]
+trait FnOnce<Args> {
+    type Output;
+}
+#[lang = "fn_mut"]
+trait FnMut<Args>: FnOnce<Args> { }
+
+enum Option<T> { Some(T), None }
+use Option::*;
+
+pub trait Iterator {
+    type Item;
+
+    fn filter_map<B, F>(self, f: F) -> FilterMap<Self, F>
+    where
+        F: FnMut(Self::Item) -> Option<B>,
+    { loop {} }
+
+    fn for_each<F>(self, f: F)
+    where
+        F: FnMut(Self::Item),
+    { loop {} }
+}
+
+pub trait IntoIterator {
+    type Item;
+    type IntoIter: Iterator<Item = Self::Item>;
+    fn into_iter(self) -> Self::IntoIter;
+}
+
+pub struct FilterMap<I, F> { }
+impl<B, I: Iterator, F> Iterator for FilterMap<I, F>
+where
+    F: FnMut(I::Item) -> Option<B>,
+{
+    type Item = B;
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<I: Iterator> IntoIterator for I {
+    type Item = I::Item;
+    type IntoIter = I;
+
+    fn into_iter(self) -> I {
+        self
+    }
+}
+
+struct Vec<T> {}
+impl<T> Vec<T> {
+    fn new() -> Self { loop {} }
+}
+
+impl<T> IntoIterator for Vec<T> {
+    type Item = T;
+    type IntoIter = IntoIter<T>;
+}
+
+pub struct IntoIter<T> { }
+impl<T> Iterator for IntoIter<T> {
+    type Item = T;
+}
+
+fn main() {
+    Vec::<i32>::new().into_iter()
+      .filter_map(|x| if x > 0 { Some(x as u32) } else { None })
+      .for_each(|y| { y; });
+}
+"#),
+        @r###"
+    [240; 244) 'self': Self
+    [246; 247) 'f': F
+    [331; 342) '{ loop {} }': FilterMap<Self, F>
+    [333; 340) 'loop {}': !
+    [338; 340) '{}': ()
+    [363; 367) 'self': Self
+    [369; 370) 'f': F
+    [419; 430) '{ loop {} }': ()
+    [421; 428) 'loop {}': !
+    [426; 428) '{}': ()
+    [539; 543) 'self': Self
+    [868; 872) 'self': I
+    [879; 899) '{     ...     }': I
+    [889; 893) 'self': I
+    [958; 969) '{ loop {} }': Vec<T>
+    [960; 967) 'loop {}': !
+    [965; 967) '{}': ()
+    [1156; 1287) '{     ... }); }': ()
+    [1162; 1177) 'Vec::<i32>::new': fn new<i32>() -> Vec<i32>
+    [1162; 1179) 'Vec::<...:new()': Vec<i32>
+    [1162; 1191) 'Vec::<...iter()': IntoIter<i32>
+    [1162; 1256) 'Vec::<...one })': FilterMap<IntoIter<i32>, |i32| -> Option<u32>>
+    [1162; 1284) 'Vec::<... y; })': ()
+    [1210; 1255) '|x| if...None }': |i32| -> Option<u32>
+    [1211; 1212) 'x': i32
+    [1214; 1255) 'if x >...None }': Option<u32>
+    [1217; 1218) 'x': i32
+    [1217; 1222) 'x > 0': bool
+    [1221; 1222) '0': i32
+    [1223; 1241) '{ Some...u32) }': Option<u32>
+    [1225; 1229) 'Some': Some<u32>(u32) -> Option<u32>
+    [1225; 1239) 'Some(x as u32)': Option<u32>
+    [1230; 1231) 'x': i32
+    [1230; 1238) 'x as u32': u32
+    [1247; 1255) '{ None }': Option<u32>
+    [1249; 1253) 'None': Option<u32>
+    [1273; 1283) '|y| { y; }': |u32| -> ()
+    [1274; 1275) 'y': u32
+    [1277; 1283) '{ y; }': ()
+    [1279; 1280) 'y': u32
+    "###
+    );
+}
+
+#[test]
+fn nested_assoc() {
+    let t = type_at(
+        r#"
+//- /main.rs
+struct Bar;
+struct Foo;
+
+trait A {
+    type OutputA;
+}
+
+impl A for Bar {
+    type OutputA = Foo;
+}
+
+trait B {
+    type Output;
+    fn foo() -> Self::Output;
+}
+
+impl<T:A> B for T {
+    type Output = T::OutputA;
+    fn foo() -> Self::Output { loop {} }
+}
+
+fn main() {
+    Bar::foo()<|>;
+}
+"#,
+    );
+    assert_eq!(t, "Foo");
+}
+
+#[test]
+fn trait_object_no_coercion() {
+    assert_snapshot!(
+        infer_with_mismatches(r#"
+trait Foo {}
+
+fn foo(x: &dyn Foo) {}
+
+fn test(x: &dyn Foo) {
+    foo(x);
+}
+"#, true),
+        @r###"
+    [22; 23) 'x': &dyn Foo
+    [35; 37) '{}': ()
+    [47; 48) 'x': &dyn Foo
+    [60; 75) '{     foo(x); }': ()
+    [66; 69) 'foo': fn foo(&dyn Foo)
+    [66; 72) 'foo(x)': ()
+    [70; 71) 'x': &dyn Foo
+    "###
+    );
+}