1 files changed, 41 insertions, 8 deletions

diff --git a/crates/ra_hir/src/ty/infer.rs b/crates/ra_hir/src/ty/infer.rs
index 52a49070a..827addddd 100644
--- a/crates/ra_hir/src/ty/infer.rs
+++ b/crates/ra_hir/src/ty/infer.rs
@@ -40,7 +40,7 @@ use crate::{
         PatId, Statement, UnaryOp,
     },
     generics::{GenericParams, HasGenericParams},
-    name::{INTO_ITERATOR, ITEM, ITER, SELF_TYPE, STD},
+    name,
     nameres::{Namespace, PerNs},
     path::{GenericArg, GenericArgs, PathKind, PathSegment},
     resolve::{
@@ -843,7 +843,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
         // Parent arguments are unknown, except for the receiver type
         if let Some(parent_generics) = def_generics.and_then(|p| p.parent_params.clone()) {
             for param in &parent_generics.params {
-                if param.name == SELF_TYPE {
+                if param.name == name::SELF_TYPE {
                     substs.push(receiver_ty.clone());
                 } else {
                     substs.push(Ty::Unknown);
@@ -1140,8 +1140,23 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                 self.insert_type_vars(ty)
             }
             Expr::Try { expr } => {
-                let _inner_ty = self.infer_expr(*expr, &Expectation::none());
-                Ty::Unknown
+                let inner_ty = self.infer_expr(*expr, &Expectation::none());
+                let ty = match self.resolve_ops_try_ok() {
+                    Some(ops_try_ok_alias) => {
+                        let ty = self.new_type_var();
+                        let projection = ProjectionPredicate {
+                            ty: ty.clone(),
+                            projection_ty: ProjectionTy {
+                                associated_ty: ops_try_ok_alias,
+                                parameters: vec![inner_ty].into(),
+                            },
+                        };
+                        self.obligations.push(Obligation::Projection(projection));
+                        self.resolve_ty_as_possible(&mut vec![], ty)
+                    }
+                    None => Ty::Unknown,
+                };
+                ty
             }
             Expr::Cast { expr, type_ref } => {
                 let _inner_ty = self.infer_expr(*expr, &Expectation::none());
@@ -1347,15 +1362,33 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
         let into_iter_path = Path {
             kind: PathKind::Abs,
             segments: vec![
-                PathSegment { name: STD, args_and_bindings: None },
-                PathSegment { name: ITER, args_and_bindings: None },
-                PathSegment { name: INTO_ITERATOR, args_and_bindings: None },
+                PathSegment { name: name::STD, args_and_bindings: None },
+                PathSegment { name: name::ITER, args_and_bindings: None },
+                PathSegment { name: name::INTO_ITERATOR, args_and_bindings: None },
             ],
         };
 
         match self.resolver.resolve_path_segments(self.db, &into_iter_path).into_fully_resolved() {
             PerNs { types: Some(Def(Trait(trait_))), .. } => {
-                Some(trait_.associated_type_by_name(self.db, ITEM)?)
+                Some(trait_.associated_type_by_name(self.db, name::ITEM)?)
+            }
+            _ => None,
+        }
+    }
+
+    fn resolve_ops_try_ok(&self) -> Option<TypeAlias> {
+        let ops_try_path = Path {
+            kind: PathKind::Abs,
+            segments: vec![
+                PathSegment { name: name::STD, args_and_bindings: None },
+                PathSegment { name: name::OPS, args_and_bindings: None },
+                PathSegment { name: name::TRY, args_and_bindings: None },
+            ],
+        };
+
+        match self.resolver.resolve_path_segments(self.db, &ops_try_path).into_fully_resolved() {
+            PerNs { types: Some(Def(Trait(trait_))), .. } => {
+                Some(trait_.associated_type_by_name(self.db, name::OK)?)
             }
             _ => None,
         }