https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94004
--- Comment #2 from Martin Sebor <msebor at gcc dot gnu.org> --- Bisection points to r254630 which doesn't look related to -Walloca: commit 025d57f037ad13eb479818b677ef4be4d97b639c Author: Martin Sebor <mse...@redhat.com> Date: Fri Nov 10 16:35:26 2017 +0000 PR c/81117 - Improve buffer overflow checking in strncpy gcc/ChangeLog: PR c/81117 * builtins.c (compute_objsize): Handle arrays that compute_builtin_object_size likes to fail for. Make extern. * builtins.h (compute_objsize): Declare. (check_strncpy_sizes): New function. (expand_builtin_strncpy): Call check_strncpy_sizes. * gimple-fold.c (gimple_fold_builtin_strncpy): Implement -Wstringop-truncation. (gimple_fold_builtin_strncat): Same. * gimple.c (gimple_build_call_from_tree): Set call location. * tree-ssa-strlen.c (strlen_to_stridx): New global variable. (maybe_diag_bound_equal_length, is_strlen_related_p): New functions. (handle_builtin_stxncpy, handle_builtin_strncat): Same. (handle_builtin_strlen): Use strlen_to_stridx. (strlen_optimize_stmt): Handle flavors of strncat, strncpy, and stpncpy. Use strlen_to_stridx. (pass_strlen::execute): Release strlen_to_stridx. * doc/invoke.texi (-Wsizeof-pointer-memaccess): Document enhancement. (-Wstringop-truncation): Document new option. gcc/ada/ChangeLog: PR c/81117 * ada/adadecode.c (__gnat_decode): Use memcpy instead of strncpy. * ada/argv.c (__gnat_fill_arg, __gnat_fill_env): Same. gcc/c-family/ChangeLog: PR c/81117 * c-common.c (catenate_strings): Use memcpy instead of strncpy. * c-warn.c (sizeof_pointer_memaccess_warning): Handle arrays. * c.opt (-Wstringop-truncation): New option. ... From-SVN: r254630