SIGSEGV handling and stack overflow handling broken in Cygwin 3.6.0

[Takashi Yano]

On Mon, 24 Mar 2025 13:26:27 +0100
Bruno Haible wrote:
> Hi,
> 
> Gnulib contains a few unit tests for
>   - SIGSEGV handling,
>   - stack overflow handling (via signal SIGSEGV or SIGBUS).
> 
> In Cygwin 3.4.6, SISGEGV handling was fine, and stack overflow handling
> worked at least for the first stack overflow.
> 
> In Cygwin 3.5.6, SISGEGV handling was fine, but stack overflow handling
> randomly worked for the first stack overflow or did not work, reminding
> me of the raise() bug [1].
> 
> In Cygwin 3.6.0, SISGEGV handling and stack overflow handling are both
> broken. Not randomly, but always reproducible.
> 
> 
> How to reproduce
> ================
> 
> 1. Create a testdir for gnulib's c-stack module:
> $ ./gnulib-tool --create-testdir --dir=../testdir1 --single-configure c-stack
> 2. Transfer it to a Cygwin machine.
> 3. Build it: ./configure && make && make check

Thanks for the report and reprodusible steps.
In my environment, one of your problems is reproduced.

FAIL: test-c-stack.sh
PASS: test-sigsegv-catch-segv2.exe

$ uname -a
CYGWIN_NT-10.0-19045 HP-Z230 3.6.0-1.x86_64 2025-03-18 17:01 UTC x86_64 Cygwin

I'll look into the stack overflow issue for now.

-- 
Takashi Yano <takashi.yano@nifty.ne.jp>