Attempting to compile a 32-bit C++ program that uses fcntl.h or sys/ioctl.h if _TIME_BITS=64 results in an error related to exception handling.

Sample code:

#include <fcntl.h>

int main(void)
{
        return 0;
}

Compile with: g++ -m32 -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE64_SOURCE -D_TIME_BITS=64 -c test.cpp

Results:

In file included from /usr/include/features.h:488,
                 from /usr/include/fcntl.h:25,
                 from test.cpp:1:
/usr/include/fcntl.h:191:41: error: expected initializer before ‘noexcept’
  191 |                        __fcntl_time64)  __THROW;
      |                                         ^~~~~~~
/usr/include/fcntl.h:193:41: error: expected initializer before ‘noexcept’
  193 |                        __fcntl_time64)  __THROW;
      |                                         ^~~~~~~

The same code does compile if built as C code instead of as C++.

Software versions:

OS: Gentoo Linux
Arch: amd64 (Intel Core i7-3520M)
Compiler: gcc-11.1.0
glibc: 2.34