bug#71916: 31.0.50; build failure on MINGW64

[Andy Moreton <andrewjmoreton@gmail.com>]

On Wed 03 Jul 2024, Andrea Corallo wrote:

> leuven65 <leuven65@gmail.com> writes:
>
>> I found the latest version of both master and emacs-30 branch (from Monday) failed to be built on MINGW64 / windows10.
>> It failed when starting native compilation, error pops up "Cannot find libgccjit library" (from
>> comp-ensure-native-compiler), maybe the called function "load_gccjit_if_necessary / init_gccjit_functions" return error.
>>
>> But if to revert the change introduced by branch "savannah/scratch/windows-98" (merged on 2024/06/30), the build becomes
>> OK.
>>
>>  git revert 38179f85f8f7236d5de8d9a4333b6a1d4ded63f0
>>
>> So that maybe the issue is caused by the 3 commits in this branch.
>
> Hello leuven65,
>
> could you share the exact error you observe?
>
> Ccing Po Lo
>
> Thanks
>
>   Andrea

I've seen the same issue on emacs-30 and master branches. It seems to be
that emacs cannot find the libgccjit DLL after dumping.

Running emacs under gdb, and using a breakpoint on `redraw-display':

(gdb) r -Q
Starting program: C:\emacs\git\emacs\emacs-30\build\mingw64-x86_64-O2-native\src\emacs.exe -Q
[New Thread 11584.0x27b4]
[New Thread 11584.0x1f54]
[New Thread 11584.0x1ec8]
[New Thread 11584.0x2ad0]
[New Thread 11584.0x1a60]

Thread 1 hit Breakpoint 2, Fredraw_display () at C:/emacs/git/emacs/emacs-30/src/dispnew.c:3222

(gdb) pp Vlibrary_cache
((gccjit) (gccjit . t))

It seems odd that there are two entries here.

There is code at the end of syms_of_emacs in emacs.c that changes
Vdynamic_library_alist as a workaround for something similar, so have
other changes made that ineffective ?

    AndyM