Hi, this patch fixes PR58893, which is an access to uninitialized memory, which may or may not crash in linemap_resolve_location, or just print error messages with bogus location.
When the first -include file is processed we have the case, where pfile->cur_token == pfile->cur_run->base, this is directly called by the front end. However in the case of the second -include file, this is called from _cpp_lex_token -> _cpp_get_fresh_line -> cpp_push_include, with pfile->cur_token != pfile->cur_run->base, and pfile->cur_token[-1].src_loc and token not (yet) initialized. The problem is, when the include file cannot be found, we need src_loc to be initialized to some safe value: 0 means UNKNOWN_LOCATION. Regarding the hunk in cpp_diagnostic, which is not directly involved in this bug, but it is still obviously wrong: The line "src_loc = pfile->cur_run->prev->limit->src_loc" is probably unreachable, but will crash it is ever executed. see: _cpp_init_tokenrun (tokenrun *run, unsigned int count) { run->base = XNEWVEC (cpp_token, count); run->limit = run->base + count; run->next = NULL; } so, limit points at the end of the run. Boot-Strapped and Regression-tested on x86_64-linux-gnu Ok for trunk? Thanks Bernd.