Merge #8056

8056: completion relevance consider if types can be unified r=JoshMcguigan a=JoshMcguigan

This PR improves completion relevance scoring for generic types, in cases where the types could unify. 

### Before

![pre-could-unify](https://user-images.githubusercontent.com/22216761/111338556-46d94e80-8634-11eb-9936-2b20eb9e6756.png)

### After

![post-could-unify](https://user-images.githubusercontent.com/22216761/111338598-4e005c80-8634-11eb-92e0-69c2c1cda6fc.png)

changelog feature improve completions

Co-authored-by: Josh Mcguigan <[email protected]>

1 files changed, 4 insertions, 0 deletions

diff --git a/crates/hir_ty/src/infer/unify.rs b/crates/hir_ty/src/infer/unify.rs
index 75250a369..6e7b0f5a6 100644
--- a/crates/hir_ty/src/infer/unify.rs
+++ b/crates/hir_ty/src/infer/unify.rs
@@ -157,6 +157,10 @@ impl<T> Canonicalized<T> {
     }
 }
 
+pub fn could_unify(t1: &Ty, t2: &Ty) -> bool {
+    InferenceTable::new().unify(t1, t2)
+}
+
 pub(crate) fn unify(tys: &Canonical<(Ty, Ty)>) -> Option<Substitution> {
     let mut table = InferenceTable::new();
     let vars = Substitution(