https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103415
--- Comment #6 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Jakub Jelinek <ja...@gcc.gnu.org>: https://gcc.gnu.org/g:ac5fd364f0978c62ae759e7b36ce6b912a27546c commit r12-5651-gac5fd364f0978c62ae759e7b36ce6b912a27546c Author: Jakub Jelinek <ja...@redhat.com> Date: Wed Dec 1 10:07:59 2021 +0100 libcpp: Fix up #__VA_OPT__ handling [PR103415] stringify_arg uses pfile->u_buff to create the string literal. Unfortunately, paste_tokens -> _cpp_lex_direct -> lex_number -> _cpp_unaligned_alloc can in some cases use pfile->u_buff too, which results in losing everything prepared for the string literal until the token pasting. The following patch fixes that by not calling paste_token during the construction of the string literal, but doing that before. All the tokens we are processing have been pushed into a token buffer using tokens_buff_add_token so it is fine if we paste some of them in that buffer (successful pasting creates a new token in that buffer), move following tokens if any to make it contiguous, pop (throw away) the extra tokens at the end and then do stringify_arg. Also, paste_tokens now copies over PREV_WHITE and PREV_FALLTHROUGH flags from the original lhs token to the replacement token. Copying that way the PREV_WHITE flag is needed for the #__VA_OPT__ handling and copying over PREV_FALLTHROUGH fixes the new Wimplicit-fallthrough-38.c test. 2021-12-01 Jakub Jelinek <ja...@redhat.com> PR preprocessor/103415 libcpp/ * macro.c (stringify_arg): Remove va_opt argument and va_opt handling. (paste_tokens): On successful paste or in PREV_WHITE and PREV_FALLTHROUGH flags from the *plhs token to the new token. (replace_args): Adjust stringify_arg callers. For #__VA_OPT__, perform token pasting in a separate loop before stringify_arg call. gcc/testsuite/ * c-c++-common/cpp/va-opt-8.c: New test. * c-c++-common/Wimplicit-fallthrough-38.c: New test.