MacOS, compile for older Macs (crash)

[Jan Wielemaker]

Hi,

I'm trying to build an application (SWI-Prolog) on MacOS using brand new 
Mac running 10.14.  The app should be running on 10.12 and later (Qt 
5.12 is part of this and requires 10.12).  So, I tried:

CFLAGS="-mmacosx-version-min=10.12 -O2" ./configure --prefix=$PREFIX \
        --enable-shared --disable-static

This produces a fine library that passes all GMP and SWI-Prolog tests
on the build machine.  However, one user reports that it crashes on
a 2009 MacPro running 10.13.6 while it runs on a more recent MacBook
running the same OS.  The crash is

?- X is 1*(1 rdiv 2).

SWI-Prolog [thread 1 (main) at Thu Apr 25 17:29:30 2019]: received fatal 
signal 4 (ill)
C-stack trace labeled "crash":
   [0] 
/Applications/SWI-Prolog-3.app/Contents/Frameworks/libswipl.8.1.5.dylib(save_backtrace+0xee) 
[0x107c9094e]
   [1] 
/Applications/SWI-Prolog-3.app/Contents/Frameworks/libswipl.8.1.5.dylib(sigCrashHandler+0xb2) 
[0x107c90f72]
   [2] 
/Applications/SWI-Prolog-3.app/Contents/Frameworks/libswipl.8.1.5.dylib(dispatch_signal+0x233) 
[0x107c1d1c3]
   [3] /usr/lib/system/libsystem_platform.dylib(_sigtramp+0x1a) 
[0x7fff64fe6f5a]
   [5] 
/Applications/SWI-Prolog-3.app/Contents/Frameworks/libgmp.10.dylib(__gmpq_mul+0x1a9) 
[0x107d16239]
   [6] 
/Applications/SWI-Prolog-3.app/Contents/Frameworks/libswipl.8.1.5.dylib(ar_mul+0xb0) 
[0x107bba7c0]

According to otool -l, the 10.12 requirement is in libgmp.10.dylib.

Does anyone has a clue?  Could it be that I also need a more 
conservative CPU selection?   Suggestions?

Notes: compiled with most recent Xcode, where gcc is in fact clang.
Report at 
https://github.com/SWI-Prolog/issues/issues/83#issuecomment-486848264

	Thanks --- Jan