cc.get_define does not work when doing universal builds

Describe the bug

cc.get_define uses $CFLAGS with -E. That is not legal. You should only be using $CPPFLAGS when using $CC -E.

Using $CFLAGS causes configure to fail when building a fat binary, eg mesa does:

cc.get_define('ETIME', prefix : '#include <errno.h>')

We setup our CFLAGS and run meson, eg:

$ CFLAGS="-arch x86_64 -arch arm64" meson build/

but this fails with the following shown in the meson log:

Command line:  cc /var/folders/99/yp4q7wrs6ts8mlgwy6njn6280000gn/T/tmpl8i1u1kl/testfile.c -pipe -E -P -arch x86_64 -arch arm64 -P -O0 -std=c11 

Code:
 
        #include <errno.h>
        #ifndef ETIME
        # define ETIME
        #endif
        "MESON_GET_DEFINE_DELIMITER"
ETIME
Compiler stdout:
 
Compiler stderr:
 clang: error: cannot use 'cpp-output' output with multiple -arch options

system parameters

• Is this a cross build or just a plain native build (for the same computer)? Native
• what operating system? macOS 11
• what Python version? 3.8.7
• what meson --version? 0.55.3
• what ninja --version if it’s a Ninja build ? 1.10.2

[kencu]

On MacPorts we use your existing cross-file system, and set up one build for each arch, with cross-files for each arch we support. Then we lipo them together at the end.

This works for now, for us.

But if you made it work transparently such that cross-files were not needed, all the better.

[barracuda156]

for interest, here are the three cross-files we use so far (the PPC one I haven’t set up yet).

Just to update, we have cross-files for ppc and ppc64 now. That works, mostly. Some issues remain, like with gobject-introspection on 10.5.8 (ppc+ppc64) and on 10.6.8 (ppc via Rosetta).

See for example: https://github.com/mesonbuild/meson/pull/10442 A suboptimal fix for Rosetta build: https://github.com/mesonbuild/meson/issues/10351#issuecomment-1131530681