Re: gnulib m4/threadlib.m4 bug crashing package tests

[Yaakov Selkowitz <yselkowitz@cygwin.com>]

On Thu, 2021-11-25 at 11:26 -0500, Ken Brown via Cygwin-apps wrote:
> On 9/29/2021 7:46 PM, Brian Inglis wrote:
> > There is a gnulib bug in threadlib.m4 from at least serial 29 to serial
> > 31 that incorrectly configures Cygwin support of weak references.
> > 
> > This leads to SIGSEGV stack smashing crashes with no backtrace
> > @ 0x00000000100000000 or 0x0000000500000000 etc. normally during tests.
> > 
> > Akim Demaille on bug-bison referred the issue to bug-gnulib where
> > Bruno Haible diagnosed and patched the problem to appear in
> > m4/threadlib.m4 serial 32:
> > 
> > * m4/threadlib.m4 (gl_WEAK_SYMBOLS): Force a "guessing no" result on
> > Cygwin
> > https://lists.gnu.org/archive/html/bug-gnulib/2021-09/msg00068.html
> > [gl_cv_have_weak="guessing no"]
> > 
> > The patch has now been applied to bison, wget, and wget2, and I have
> > attached my patches for the copies in those packages, in case anyone
> > else has this issue in their (mainly GNU) packages which may incorporate
> > by 
> > inclusion recently updated gnulib m4 macros used in autotools builds.
> 
> Thanks, Brian.
> 
> I'm writing to reinforce this warning.  I just spent 2 days trying to debug 
> mysterious texinfo crashes that were caused by this bug.  I could have saved
> a 
> lot of time if I had remembered your email and had checked the gnulib
> version 
> being used by texinfo.
> 
> For anyone else who bumps into this, gdb and strace are of no use in
> debugging 
> this crash.  I finally thought to look at the stackdump file, and the second
> address from the top was in a gnulib file.  That was the key clue.

Add gl_cv_have_weak=no to cygconf?

-- 
Yaakov