https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117153
--- Comment #4 from Marek Polacek <mpolacek at gcc dot gnu.org> --- Candidate fix: --- a/gcc/cp/decl2.cc +++ b/gcc/cp/decl2.cc @@ -1960,7 +1960,10 @@ build_anon_union_vars (tree type, tree object) if (processing_template_decl) ref = build_min_nt_loc (UNKNOWN_LOCATION, COMPONENT_REF, object, - DECL_NAME (field), NULL_TREE); + (DECL_NAME (field) + ? DECL_NAME (field) + : make_anon_name ()), + NULL_TREE); else ref = build_class_member_access_expr (object, field, NULL_TREE, false, tf_warning_or_error);