Warning when including ffi.h on i386/x86 machines

[dpgeorge]

System Details

• Intel x86-64 machine, Arch Linux
• libffi version 3.4.4-1 and lib32-lbiffi version 3.4.4-1 (from Arch Linux package manager)

Problems Description

The following warning is obtained when building with gcc -m32, ie in 32-bit mode (and since -Werror is used this turns into a compile error):

/usr/include/ffitarget.h:44:2: error: #warning ****************************************************** [-Werror=cpp]
   44 | #warning ******************************************************
      |  ^~~~~~~
/usr/include/ffitarget.h:45:2: error: #warning ********** X86 IS DEFINED **************************** [-Werror=cpp]
   45 | #warning ********** X86 IS DEFINED ****************************
      |  ^~~~~~~
/usr/include/ffitarget.h:46:2: error: #warning ****************************************************** [-Werror=cpp]
   46 | #warning ******************************************************
      |  ^~~~~~~
cc1: all warnings being treated as errors

It seems like this problem was introduced in commit b05dc51, which simply added this warning message. Since ffi.h unconditionally defines the symbol X64_64 it's hard to see how this warning could be avoided.

What is the correct way to use libffi on a 64-bit machine in 32-bit mode (ie gcc -m32)?