New comment by tornaria on void-packages repository

https://github.com/void-linux/void-packages/pull/34030#issuecomment-1002287099

Comment:
Somehow it seems `abort()` is raising a `SIGSEGV` instead of a `SIGABRT`. You can see the different behaviour doing:
```
sage: from cysignals.signals import sig_print_exception
sage: import signal
sage: sig_print_exception(signal.SIGABRT, "matrix allocation failed")
RuntimeError: matrix allocation failed
sage: sig_print_exception(signal.SIGSEGV, "matrix allocation failed")
cysignals.signals.SignalError: matrix allocation failed
```

Now if I comment out the `_sig_str(...)` line in `matrix_mod2_dense.pyx` this happens:
```
sage: import resource
sage: resource.setrlimit(resource.RLIMIT_AS, (4*1024^3, -1))
sage: MatrixSpace(GF(2), 2^30)(1)
------------------------------------------------------------------------
/usr/lib/sage-9.5.beta9/local/var/lib/sage/venv-python3.10/bin/cysignals-CSI:42: DeprecationWarning: The distutils package is deprecated and slated for removal in Python 3.12. Use setuptools or check PEP 632 for potential alternatives
  from distutils.spawn import find_executable
Attaching gdb to process id 1026.
Cannot find gdb installed
GDB is not installed.
Install gdb for enhanced tracebacks.
------------------------------------------------------------------------
Unhandled SIGSEGV: A segmentation fault occurred.
This probably occurred because a *compiled* module has a bug
in it and is not properly wrapped with sig_on(), sig_off().
Python will now terminate.
------------------------------------------------------------------------
```

Looking at the backtrace (after installing `gdb` and `musl-devel`) seems to imply that `posix_memalign()` never returns, instead segfaulting, so that the `abort()` in `m4ri` code is never called:
```
Stack backtrace
---------------
No locals.
#1  0x00007f22c9707fc1 in __syscall_cp_c (nr=61, u=1878, v=0, 
    w=<optimized out>, x=<optimized out>, y=<optimized out>, z=0)
    at src/thread/pthread_cancel.c:33
        self = 0x7f22c9751b08 <builtin_tls+136>
        r = <optimized out>
        st = <optimized out>
#2  0x00007f22c96edf72 in waitpid (pid=<optimized out>, 
    status=status@entry=0x0, options=options@entry=0)
    at src/process/waitpid.c:6
No locals.
#3  0x00007f22c695e774 in print_enhanced_backtrace ()
    at build/src/cysignals/implementation.c:586
        parent_pid = 1813
        pid = <optimized out>
#4  0x00007f22c695e8d9 in sigdie (sig=sig@entry=11, 
    s=s@entry=0x7f22c69660b0 "Unhandled SIGSEGV: A segmentation fault occurred.") at build/src/cysignals/implementation.c:612
No locals.
#5  0x00007f22c6961e33 in sigdie_for_sig (inside=0, sig=11)
    at build/src/cysignals/implementation.c:179
No locals.
#6  cysigs_signal_handler (sig=11) at build/src/cysignals/implementation.c:278
        inside = <optimized out>
#7  <signal handler called>
No locals.
#8  get_meta (p=0x0) at src/malloc/mallocng/meta.h:132
        offset = <optimized out>
        index = <optimized out>
        base = <optimized out>
        meta = <optimized out>
        area = <optimized out>
        offset = <optimized out>
        index = <optimized out>
        base = <optimized out>
        meta = <optimized out>
        area = <optimized out>
#9  aligned_alloc (align=64, len=8589934600)
    at src/malloc/mallocng/aligned_alloc.c:25
        p = 0x0
        g = <optimized out>
        idx = <optimized out>
        stride = <optimized out>
        start = <optimized out>
        end = <optimized out>
        adj = <optimized out>
        offset = <optimized out>
#10 0x00007f22c96cbb7a in posix_memalign (res=0x7ffdd6f1bc70, 
    align=<optimized out>, len=<optimized out>)
    at src/malloc/posix_memalign.c:7
        mem = <optimized out>
#11 0x00007f223b02ddfb in m4ri_mmc_malloc () from /lib/libm4ri-0.0.20200125.so
No symbol table info available.
#12 0x00007f223b015a7a in mzd_init () from /lib/libm4ri-0.0.20200125.so
No symbol table info available.
...
```
```