handle match auto-deref

crates/ra_hir_ty/src/_match.rs

@@ -865,6 +865,41 @@ mod tests {
         check_no_diagnostic(content);
     }
 
+    #[test]
+    fn enum_ref_missing_arms() {
+        let content = r"
+            enum Either {
+                A,
+                B,
+            }
+            fn test_fn() {
+                match &Either::B {
+                    Either::A => {},
+                }
+            }
+        ";
+
+        check_diagnostic_with_no_fix(content);
+    }
+
+    #[test]
+    fn enum_ref_no_diagnostic() {
+        let content = r"
+            enum Either {
+                A,
+                B,
+            }
+            fn test_fn() {
+                match &Either::B {
+                    Either::A => {},
+                    Either::B => {},
+                }
+            }
+        ";
+
+        check_no_diagnostic(content);
+    }
+
     #[test]
     fn enum_containing_bool_no_arms() {
         let content = r"

crates/ra_hir_ty/src/expr.rs

@@ -93,7 +93,16 @@ impl<'a, 'b> ExprValidator<'a, 'b> {
                 // of the match expression. If we had a InvalidMatchArmPattern
                 // diagnostic or similar we could raise that in an else
                 // block here.
-                if pat_ty == match_expr_ty {
+                //
+                // When comparing the types, we also have to consider that rustc
+                // will automatically de-reference the match expression type if
+                // necessary.
+                if pat_ty == match_expr_ty
+                    || match_expr_ty
+                        .as_reference()
+                        .map(|(match_expr_ty, _)| match_expr_ty == pat_ty)
+                        .unwrap_or(false)
+                {
                     // If we had a NotUsefulMatchArm diagnostic, we could
                     // check the usefulness of each pattern as we added it
                     // to the matrix here.