add check and don't encode #[inline]

Author: lcnr

compiler/rustc_feature/src/builtin_attrs.rs

@@ -377,7 +377,7 @@ pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
     ungated!(panic_handler, Normal, template!(Word), WarnFollowing), // RFC 2070
 
     // Code generation:
-    ungated!(inline, Normal, template!(Word, List: "always|never"), FutureWarnFollowing),
+    ungated!(inline, Normal, template!(Word, List: "always|never"), FutureWarnFollowing, @only_local: true),
     ungated!(cold, Normal, template!(Word), WarnFollowing),
     ungated!(no_builtins, CrateLevel, template!(Word), WarnFollowing),
     ungated!(target_feature, Normal, template!(List: r#"enable = "name""#), DuplicatesOk),

compiler/rustc_middle/src/ty/mod.rs

@@ -2201,6 +2201,9 @@ impl<'tcx> TyCtxt<'tcx> {
 
     /// Determines whether an item is annotated with an attribute.
     pub fn has_attr(self, did: DefId, attr: Symbol) -> bool {
+        if cfg!(debug_assertions) && !did.is_local() && rustc_feature::is_builtin_only_local(attr) {
+            bug!("tried to access the `only_local` attribute `{}` from an extern crate", attr);
+        }
         self.sess.contains_name(&self.get_attrs(did), attr)
     }