Fix handling of const patterns

E.g. in `match x { None => ... }`, `None` is a path pattern (resolving to the
option variant), not a binding. To determine this, we need to try to resolve the
name during lowering. This isn't too hard since we already need to resolve names
for macro expansion anyway (though maybe a bit hacky).

Fixes #1618.

1 files changed, 3 insertions, 1 deletions

diff --git a/crates/ra_hir_ty/src/infer/pat.rs b/crates/ra_hir_ty/src/infer/pat.rs
index a495ecbfe..bf8ea192b 100644
--- a/crates/ra_hir_ty/src/infer/pat.rs
+++ b/crates/ra_hir_ty/src/infer/pat.rs
@@ -189,7 +189,9 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
         };
         // use a new type variable if we got Ty::Unknown here
         let ty = self.insert_type_vars_shallow(ty);
-        self.unify(&ty, expected);
+        if !self.unify(&ty, expected) {
+            // FIXME record mismatch, we need to change the type of self.type_mismatches for that
+        }
         let ty = self.resolve_ty_as_possible(ty);
         self.write_pat_ty(pat, ty.clone());
         ty