bug#42891: 28.0.50; High Sierra Macos build failure

[Lars Ingebrigtsen]

I set up a bunch of VMs with different Macos versions, and Emacs builds
fine on Mojave and Catalina, but not High Sierra (which is the oldest of
the supported Macos versions).

It fails with

/Library/Developer/CommandLineTools/usr/bin/make -C ../lisp update-subdirs
cp -f temacs bootstrap-emacs
rm -f bootstrap-emacs.pdmp
./temacs --batch  -l loadup --temacs=pbootstrap
make[2]: *** [bootstrap-emacs.pdmp] Segmentation fault: 11 (core dumped)
make[1]: *** [src] Error 2
make: *** [bootstrap] Error 2

Larss-iMac:trunk larsi$ gcc --version
Configured with: --prefix=/Library/Developer/CommandLineTools/usr 
--with-gxx-include-dir=/usr/include/c++/4.2.1
Apple LLVM version 10.0.0 (clang-1000.10.44.4)
Target: x86_64-apple-darwin17.7.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin

I don't know whether we care about this system or not?  Is that a
too-old clang version for us to worry about this?

I'm completely unfamiliar with how lldb works...  this backtrace doesn't
looke very useful?

Larss-iMac:trunk larsi$ lldb src/temacs --core /cores/core.36630 
(lldb) target create "src/temacs" --core "/cores/core.36630"
warning: (x86_64) /cores/core.36630 load command 200 LC_SEGMENT_64 has a 
fileoff + filesize (0x4ead2000) that extends beyond the end of the file 
(0x4ead1000), the segment will be truncated to match
warning: (x86_64) /cores/core.36630 load command 201 LC_SEGMENT_64 has a 
fileoff (0x4ead2000) that extends beyond the end of the file (0x4ead1000), 
ignoring this section
Core file '/cores/core.36630' (x86_64) was loaded.
(lldb) bt all
* thread #1, stop reason = signal SIGSTOP
  * frame #0: 0x00007fff50f81993 
libsystem_platform.dylib`_platform_memmove$VARIANT$Base + 1875
  thread #2, stop reason = signal SIGSTOP
    frame #0: 0x00007fff50dc028a libsystem_kernel.dylib`__workq_kernreturn + 10
    frame #1: 0x00007fff50f8720e libsystem_pthread.dylib`_pthread_wqthread + 
1552
    frame #2: 0x00007fff50f86be9 libsystem_pthread.dylib`start_wqthread + 13
  thread #3, stop reason = signal SIGSTOP
    frame #0: 0x00007fff50dc028a libsystem_kernel.dylib`__workq_kernreturn + 10
    frame #1: 0x00007fff50f87009 libsystem_pthread.dylib`_pthread_wqthread + 
1035
    frame #2: 0x00007fff50f86be9 libsystem_pthread.dylib`start_wqthread + 13



In GNU Emacs 28.0.50 (build 11, x86_64-pc-linux-gnu, GTK+ Version 3.24.20, 
cairo version 1.16.0)
 of 2020-08-13 built on xo
Repository revision: 1bed252ae9109493133a0cc3e9aad9e9a5ddde37
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12008000
System Description: Debian GNU/Linux bullseye/sid

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no