Properly prevent the promotion of unstable const fns

Author: oli-obk

Diff for: src/librustc_mir/transform/qualify_consts.rs

@@ -127,6 +127,7 @@ impl<'a, 'tcx> Qualifier<'a, 'tcx, 'tcx> {
            mir: &'a Mir<'tcx>,
            mode: Mode)
            -> Qualifier<'a, 'tcx, 'tcx> {
+        assert!(def_id.is_local());
         let mut rpo = traversal::reverse_postorder(mir);
         let temps = promote_consts::collect_temps(mir, &mut rpo);
         rpo.reset();
@@ -915,9 +916,6 @@ impl<'a, 'tcx> Visitor<'tcx> for Qualifier<'a, 'tcx, 'tcx> {
                             .iter()
                             .any(|&(ref sym, _)| sym == feature_name) &&
 
-                        // this doesn't come from a crate with the feature-gate enabled,
-                        self.def_id.is_local() &&
-
                         // this doesn't come from a macro that has #[allow_internal_unstable]
                         !self.span.allows_unstable()
                     {

Diff for: src/librustc_passes/rvalue_promotion.rs

@@ -189,9 +189,6 @@ impl<'a, 'gcx> CheckCrateVisitor<'a, 'gcx> {
                     .iter()
                     .any(|&(ref sym, _)| sym == feature_name) ||
 
-                    // this comes from a crate with the feature-gate enabled,
-                    !def_id.is_local() ||
-
                     // this comes from a macro that has #[allow_internal_unstable]
                     span.allows_unstable();
             if !stable_check {