Auto merge of #13242 - Veykril:completion-alias, r=Veykril

Complete variants and assoc items in path pattern through type aliases

Author: bors

crates/ide-completion/src/completions/pattern.rs

@@ -145,6 +145,7 @@ pub(crate) fn complete_pattern_path(
                             u.ty(ctx.db)
                         }
                         hir::PathResolution::Def(hir::ModuleDef::BuiltinType(ty)) => ty.ty(ctx.db),
+                        hir::PathResolution::Def(hir::ModuleDef::TypeAlias(ty)) => ty.ty(ctx.db),
                         _ => return,
                     };
 

crates/ide-completion/src/tests/pattern.rs

@@ -714,3 +714,30 @@ impl Ty {
         "#]],
     );
 }
+
+#[test]
+fn through_alias() {
+    check_empty(
+        r#"
+enum Enum<T> {
+    Unit,
+    Tuple(T),
+}
+
+type EnumAlias<T> = Enum<T>;
+
+fn f(x: EnumAlias<u8>) {
+    match x {
+        EnumAlias::$0 => (),
+        _ => (),
+    }
+
+}
+
+"#,
+        expect![[r#"
+            bn Tuple(…) Tuple($1)$0
+            bn Unit     Unit$0
+        "#]],
+    );
+}