https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101238
--- Comment #2 from Tomas Kalibera <tomas.kalibera at gmail dot com> --- I started writing that email, but on the way I found that one should add -D__USE_MINGW_ACCESS also BOOT_CXXFLAGS, which I have neither done nor tested. The problem I debugged required only required adding to CXXFLAGS. In principle, one needs to add -D__USE_MINGW_ACCESS everywhere, where GCC might use "access()" to query X_OK, so it should be safe to add simply everywhere when compiling C or C++, it just must have been forgotten. I see -D__USE_MINGW_ACCESS has been added to CXXFLAGS and BOOT_CXXFLAGS in GCC 11 by a patch from Martin Storsjo, "mh-mingw: Set __USE_MINGW_ACCESS in missed C++ flags variables", https://gcc.gnu.org/pipermail/gcc-patches/2021-April/567815.html And it is related to "[MinGW] Set __USE_MINGW_ACCESS for C++ as well" https://gcc.gnu.org/pipermail/gcc-patches/2019-March/518147.html (done also in GCC 10), which adds __USE_MINGW_ACCESS to STAGE*_CXXFLAGS. My testing was using an MXE-based build of GCC 10.2 (cross-compiled on Linux, for 64-bit Windows, with MinGW-w64 7). Without the change, gcc.exe did not find cc1.exe. Process monitor showed that gcc.exe called stat on cc1.exe successfully (so used the correct path already the first time), but then continued checking other locations and when it failed, tried to execute without path name (relying on system PATH). So a workaround I have been using was to have also cc1.exe on PATH, where it would be found by Windows (so the problem of access(,X_OK) did not apply there). Then the observed behavior matched the code of the driver gcc.c, which calls access(,X_OK) to check that cc1.exe is executable, and it incorrectly concludes that it isn't. Which in turn is because access on Windows does not support X_OK (and __USE_MINGW_ACCESS provides a MinGW replacement which does). I've confirmed this was what happened via adding print statements to the driver and rebuilding. And eventually I rebuilt gcc with the proposed patch and it found cc1.exe fine. Should I still send a copy of Martin Storsjo's patch to gcc-patc...@gcc.gnu.org, or is this information here now sufficient?
