$ x86_64-w64-mingw32-g++ test.cc -I build-gnulib-gdbserver/import/ -I ~/binutils-gdb/gnulib/import/
In file included from /usr/share/mingw-w64/include/io.h:10,
                 from /usr/share/mingw-w64/include/unistd.h:10,
                 from build-gnulib-gdbserver/import/unistd.h:40,
                 from /usr/local/google/home/cbiesinger/binutils-gdb/gnulib/import/pathmax.h:42,
                 from test.cc:2:
build-gnulib-gdbserver/import/time.h:500:1: error: conflicting declaration of ‘tm* localtime_r(const time_t*, tm*)’ with ‘C’ linkage
 _GL_FUNCDECL_SYS (localtime_r, struct tm *, (time_t const *restrict __timer,
 ^~~~~~~~~~~~~~~~
In file included from build-gnulib-gdbserver/import/time.h:41,
                 from test.cc:3:
/usr/share/mingw-w64/include/time.h:308:34: note: previous declaration with ‘C++’ linkage
 __forceinline struct tm *__cdecl localtime_r(const time_t *_Time, struct tm *_Tm) {
                                  ^~~~~~~~~~~
In file included from /usr/share/mingw-w64/include/io.h:10,
                 from /usr/share/mingw-w64/include/unistd.h:10,
                 from build-gnulib-gdbserver/import/unistd.h:40,
                 from /usr/local/google/home/cbiesinger/binutils-gdb/gnulib/import/pathmax.h:42,
                 from test.cc:2:
build-gnulib-gdbserver/import/time.h:522:1: error: conflicting declaration of ‘tm* gmtime_r(const time_t*, tm*)’ with ‘C’ linkage
 _GL_FUNCDECL_SYS (gmtime_r, struct tm *, (time_t const *restrict __timer,
 ^~~~~~~~~~~~~~~~
In file included from build-gnulib-gdbserver/import/time.h:41,
                 from test.cc:3:
/usr/share/mingw-w64/include/time.h:311:34: note: previous declaration with ‘C++’ linkage
 __forceinline struct tm *__cdecl gmtime_r(const time_t *_Time, struct tm *_Tm) {
                                  ^~~~~~~~