https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77739
--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> --- The problem is that some expressions are genericized twice. First when genericizing the whole function, RESULT_DECL is determined to be is_invisiref_parm and therefore references to it are turned into INDIRECT_REF around it and the RESULT_DECL becomes REFERENCE_TYPE. Later on gimplify_body calls unshare_body and unshares the INDIRECT_REF. Then the INDIRECT_REF is gimplified into a MEM_REF. And finally: (cp_gimplify_expr) <case VEC_INIT_EXPR> does: 625 cp_walk_tree (expr_p, cp_fold_r, &pset, NULL); 626 cp_genericize_tree (expr_p); and sees the is_invisiref_parm RESULT_DECL again (inside of MEM_REF) and turns it again into INDIRECT_REF and that is later gimplified again into MEM_REF. So we have 2 nested MEM_REFs, so one indirection too many. I think one possibility would be to be careful about REFERENCE_REF_Ps and corresponding MEM_REFs (I guess would need to double check that the offset is 0 and type is compatible with the type of the reference), if their argument is is_invisiref_parm, ensure it isn't convert_from_reference again. Will try to implement that now.
