bug#49350: gcc-toolchain compilation error with -nostdinc++

[Ontje Lünsdorf]

Hi all,


I've problems compiling LLVM manually with the gcc-toolchain.
sanitizer_posix_libcdep.cpp is build with -nostdinc++ and fails to find
bits/c++config.h.

I think the issue can be reproduced with this example test.cpp:

#include <stdlib.h>
int main() { return 0; }

c++ from archlinux compiles that file, while c++ from gcc-toolchain doesn't:

$ c++ -nostdinc++ test.cpp
$ guix environment --ad-hoc gcc-toolchain -- c++ -nostdinc++ test.cpp
In file included from 
/gnu/store/nh9r04xhzmbk3hjsj92yhlhmjsp521g4-profile/include/c++/stdlib.h:36,
                 from test.cpp:1:
/gnu/store/nh9r04xhzmbk3hjsj92yhlhmjsp521g4-profile/include/c++/cstdlib:41:10: 
fatal error: bits/c++config.h: No such file or directory
   41 | #include <bits/c++config.h>
      |          ^~~~~~~~~~~~~~~~~~
compilation terminated.

Is this expected and I'm doing something wrong?

Thanks & best regards,
Ontje