bash hangs on cygwin-3.5.5-1

[Jeremy Drake]

On Wed, 25 Dec 2024, Takashi Yano via Cygwin wrote:

> On Tue, 24 Dec 2024 22:34:44 +0100
> Bruno Haible wrote:
> > This is not reproducible, but here's the report anyway:
> >
> > I upgraded a Windows 10 system from Cygwin 3.5.3 to 3.5.5 today.
> > Then ran the configure script of a tarball (*), and it hung:
> >
> > $ mkdir build-cygwin64
> > $ cd build-cygwin64
> > $ ../configure --host=x86_64-pc-cygwin --prefix=/usr/local/cygwin64 CC=x86_64-pc-cygwin-gcc CXX=x86_64-pc-cygwin-g++ CPPFLAGS="-I/usr/local/cygwin64/include -Wall" LDFLAGS=-L/usr/local/cygwin64/lib -C --with-included-libunistring 2>&1 | tee log1
> > ...
> > checking whether snprintf fully supports the 'n' directive... (cached) yes
> > checking whether snprintf respects a size of 1... (cached) yes
> > checking whether vsnprintf respects a zero size as in C99... (cached) yes
> > checking whether btowc is declared without a macro... yes
> > checking whether wctob is declared without a macro... yes
> > checking whether mbsinit is declared without a macro... yes
> > checking whether mbrtowc is declared without a macro... yes
> > <hangs>
> >
> > Typing Ctrl-C in said mintty window has no effect.
> >
> >
> > (*) generated in a gnulib checkout on Linux, through
> >     $ ./gnulib-tool --create-testdir --dir=../testdir-all --with-c++-tests --without-privileged-tests --single-configure `./all-modules`
>
> This may be the same issue with:
> https://cygwin.com/pipermail/cygwin/2024-December/256954.html

We ran into hang issues with libtool linking imagemagick in msys2, using
version based on 3.5.5, 3 times in a row on our ARM64 runner.  We applied
your v2 patch to our 3.5.5 branch (with the change of current_sig to sig),
and the issue no longer occurred.  (I also tested with the existing 3.5.4
version, and it didn't hang either).

Note that kill -CHLD to either the child sh.exe or the parent make.exe did
not unblock things, but killing sh.exe (SIGTERM) did cause the make to
fail as expected.