https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86532
--- Comment #3 from Bernd Edlinger <bernd.edlinger at hotmail dot de> --- Hi Martin, how about: --- gcc/expr.c.jj 2018-07-09 22:33:48.000000000 +0200 +++ gcc/expr.c 2018-07-16 17:18:47.919177047 +0200 @@ -11359,6 +11359,9 @@ string_constant (tree arg, tree *ptr_off return array; } + if (varidx != NULL_TREE) + return NULL_TREE; + if (!VAR_P (array) && TREE_CODE (array) != CONST_DECL) return NULL_TREE;