Suggested change

Author: fmckeogh

src/librustc/traits/specialize/mod.rs

@@ -367,10 +367,11 @@ pub(super) fn specialization_graph_provider(
                 }
 
                 let access_levels = tcx.privacy_access_levels(impl_def_id.krate);
-                let id = tcx.hir().as_local_hir_id(impl_def_id).unwrap();
-                if access_levels.is_exported(id) || access_levels.is_public(id) {
-                    for cause in &overlap.intercrate_ambiguity_causes {
-                        cause.add_intercrate_ambiguity_hint(&mut err);
+                if let Some(id) = tcx.hir().as_local_hir_id(impl_def_id) {
+                    if access_levels.is_exported(id) || access_levels.is_public(id) {
+                        for cause in &overlap.intercrate_ambiguity_causes {
+                            cause.add_intercrate_ambiguity_hint(&mut err);
+                        }
                     }
                 }