wchar.h not found

[vitamin-caig]

Hello!

Found a problem while trying to compile with this toolchain:

/home/user/devel/haiku/cross-tools-x86_64/bin/x86_64-unknown-haiku-g++ -g -O2 -DNDEBUG -funroll-loops -finline-functions -fdata-sections -ffunction-sections -fPIC   -DHAVE_STDINT_H -funsigned-char -fno-strict-aliasing -fvisibility=hidden -W -Wall -Wextra -pipe <includes> -std=c++17 -fvisibility-inlines-hidden -c <input> -o <output> -MMD
In file included from /home/user/devel/haiku/cross-tools-x86_64/x86_64-unknown-haiku/include/c++/11.3.0/bits/postypes.h:40,
                 from /home/user/devel/haiku/cross-tools-x86_64/x86_64-unknown-haiku/include/c++/11.3.0/bits/char_traits.h:40,
                 from /home/user/devel/haiku/cross-tools-x86_64/x86_64-unknown-haiku/include/c++/11.3.0/string:40,
                 ...
/home/user/devel/haiku/cross-tools-x86_64/x86_64-unknown-haiku/include/c++/11.3.0/cwchar:44:10: fatal error: wchar.h: No such file or directory
   44 | #include <wchar.h>
      |          ^~~~~~~~~
compilation terminated.

while

$ find ~/devel/haiku/ -name 'wchar.h'
/home/user/devel/haiku/cross-tools-x86_64/x86_64-unknown-haiku/include/c++/11.3.0/tr1/wchar.h

How to force compiler to use supplied include?