https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119400
--- Comment #5 from Ilya Zylev <atstng at gmail dot com> --- Thank you very much, that clarifies original post. -fms-extensions -fno-ms-extensions options work as intended. Is it possible to configure these options from inside the source code being compiled by GCC? Probably something in form of #pragma GCC optimize("no-ms-extensions") With this question I mainly concern usage in online judges, where direct control of command line options is usually restricted.