1 files changed, 16 insertions, 0 deletions
diff --git a/compiler/rustc_passes/src/stability.rs b/compiler/rustc_passes/src/stability.rs
index 46b67e930d5..751c87a9fe5 100644
--- a/compiler/rustc_passes/src/stability.rs
+++ b/compiler/rustc_passes/src/stability.rs
@@ -10,6 +10,7 @@ use rustc_attr::{
 };
 use rustc_data_structures::fx::FxIndexMap;
 use rustc_data_structures::unord::{ExtendUnord, UnordMap, UnordSet};
+use rustc_feature::ACCEPTED_FEATURES;
 use rustc_hir as hir;
 use rustc_hir::def::{DefKind, Res};
 use rustc_hir::def_id::{CRATE_DEF_ID, LOCAL_CRATE, LocalDefId, LocalModDefId};
@@ -246,12 +247,27 @@ impl<'a, 'tcx> Annotator<'a, 'tcx> {
                 }
             }
 
+            if let Stability { level: Unstable { .. }, feature } = stab {
+                if ACCEPTED_FEATURES.iter().find(|f| f.name == feature).is_some() {
+                    self.tcx
+                        .dcx()
+                        .emit_err(errors::UnstableAttrForAlreadyStableFeature { span, item_sp });
+                }
+            }
             if let Stability { level: Unstable { implied_by: Some(implied_by), .. }, feature } =
                 stab
             {
                 self.index.implications.insert(implied_by, feature);
             }
 
+            if let Some(ConstStability { level: Unstable { .. }, feature, .. }) = const_stab {
+                if ACCEPTED_FEATURES.iter().find(|f| f.name == feature).is_some() {
+                    self.tcx.dcx().emit_err(errors::UnstableAttrForAlreadyStableFeature {
+                        span: const_span.unwrap(), // If const_stab contains Some(..), same is true for const_span
+                        item_sp,
+                    });
+                }
+            }
             if let Some(ConstStability {
                 level: Unstable { implied_by: Some(implied_by), .. },
                 feature,