early exit expand abstract consts

Author: BoxyUwU

compiler/rustc_middle/src/ty/abstract_const.rs

@@ -35,6 +35,10 @@ pub type BoundAbstractConst<'tcx> =
 
 impl<'tcx> TyCtxt<'tcx> {
     pub fn expand_abstract_consts<T: TypeFoldable<TyCtxt<'tcx>>>(self, ac: T) -> T {
+        if !self.features().generic_const_exprs() {
+            return ac
+        }
+        
         struct Expander<'tcx> {
             tcx: TyCtxt<'tcx>,
         }