Merge #892

892: Type aliases r=matklad a=flodiebold

This implements type aliases (i.e. `type` definitions).

There's just one snag: handling recursion. E.g. `type Foo = Foo` makes type inference panic with a query cycle. I think the best way to handle this would be if Salsa provided the ability to catch cycle errors? It seems that there's some work underway to support this [here](https://github.com/salsa-rs/salsa/issues/6) and [here](https://github.com/salsa-rs/salsa/pull/147). Should we wait for this? I don't see a good way to handle this without help from Salsa.

Co-authored-by: Florian Diebold <[email protected]>

1 files changed, 3 insertions, 1 deletions

diff --git a/crates/ra_hir/src/ty/infer.rs b/crates/ra_hir/src/ty/infer.rs
index 13080b5aa..29331bea5 100644
--- a/crates/ra_hir/src/ty/infer.rs
+++ b/crates/ra_hir/src/ty/infer.rs
@@ -477,7 +477,9 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                 let ty = self.insert_type_vars(ty.apply_substs(substs));
                 (ty, Some(var.into()))
             }
-            TypableDef::Function(_) | TypableDef::Enum(_) => (Ty::Unknown, None),
+            TypableDef::Type(_) | TypableDef::Function(_) | TypableDef::Enum(_) => {
+                (Ty::Unknown, None)
+            }
         }
     }