freetype @2.13.2: error: use of unknown builtin '__builtin_bswap16'

[ryandesign (Ryan Carsten Schmidt)]

freetype 2.13.2 fails to build on Lion only:

​https://build.macports.org/builders/ports-10.7_x86_64-builder/builds/163387/steps/install-port/logs/stdio

/opt/local/var/macports/build/_opt_bblocal_var_buildworker_ports_build_ports_print_freetype/freetype/work/freetype-2.13.2/src/pcf/pcfutil.c:100:12: error: use of unknown builtin '__builtin_bswap16' [-Wimplicit-function-declaration]
      *b = BSWAP16( *b );
           ^
/opt/local/var/macports/build/_opt_bblocal_var_buildworker_ports_build_ports_print_freetype/freetype/work/freetype-2.13.2/src/pcf/pcfutil.c:64:23: note: expanded from macro 'BSWAP16'
#define BSWAP16( x )  __builtin_bswap16( x )
                      ^
1 error generated.
make: *** [/opt/local/var/macports/build/_opt_bblocal_var_buildworker_ports_build_ports_print_freetype/freetype/work/freetype-2.13.2/objs/pcf.lo] Error 1
make: *** Waiting for unfinished jobs....

[ryandesign (Ryan Carsten Schmidt)]

I filed an upstream bug report:

​https://gitlab.freedesktop.org/freetype/freetype/-/issues/1260

There I pointed to a Python bug report about the same thing from a few years ago which shows how they fixed it.

We could try to adapt their fix or just blacklist the old clang versions that don't have __builtin_bswap16.

[ryandesign (Ryan Carsten Schmidt)]

In 0aa731317f187b1ebfedc8c5693199c95322bde7/macports-ports (master):

freetype: Blacklist clang < 500

See: #68448