Stabilize type-macros

Closes #27245

src/libsyntax/ext/expand.rs

@@ -491,18 +491,7 @@ fn expand_trait_item(ti: ast::TraitItem, fld: &mut MacroExpander)
 pub fn expand_type(t: P<ast::Ty>, fld: &mut MacroExpander) -> P<ast::Ty> {
     let t = match t.node.clone() {
         ast::TyKind::Mac(mac) => {
-            if fld.cx.ecfg.features.unwrap().type_macros {
-                expand_mac_invoc(mac, None, Vec::new(), t.span, fld)
-            } else {
-                feature_gate::emit_feature_err(
-                    &fld.cx.parse_sess.span_diagnostic,
-                    "type_macros",
-                    t.span,
-                    feature_gate::GateIssue::Language,
-                    "type macros are experimental");
-
-                DummyResult::raw_ty(t.span)
-            }
+            expand_mac_invoc(mac, None, Vec::new(), t.span, fld)
         }
         _ => t
     };