Failed assertion dialog box

[André Bleau]

On Fri, Nov 13, 2020 at 10:45 PM Duncan Roe 
wrote:

> Hi William,
>
> On Fri, Nov 13, 2020 at 12:27:57PM -0500, cygwin wrote:
> > I've run into a problem running a collection of tests under Cygwin and I
> > wonder if anyone can suggest a way around it.
> >
> > The problem occurs when a program being run fails a C/C++ runtime
> > assertion. Ordinarily, this just writes an error message on stderr and
> > aborts. Under Cygwin, however, if both stdin and stderr are redirected to
> > files, the program instead pops up a dialog box that must be
> interactively
> > dismissed before the failed program will exit - holding up all the tests
> > that follow it.
> >
> > Specifically, if I have the following as assert.cpp:
> >
> >     #include <assert.h>
> >     int main() {
> >       assert(false);
> >     }
> >
> > and say
> >
> >     gcc assert.cpp
> >     ./a.exe < /dev/null > output 2>&1
> >
> > I get an error dialog box saying
> >
> >     Failed assertion
> >         false
> >     at line 3 of file assert.cpp
> >     in function int main()
> >
> > If I omit either the stdin or the stderr redirection, the program behaves
> > as desired with no dialog box.
> >
> > Is there an environment setting or compiler command-line option I can
> give
> > to suppress the dialog box and always just write a message to stderr and
> > abort? Thanks for any insights.
>
> Your example WFFM, (Cygwin64, gcc 10.2.0, everything else also up to date).
>
> Do you still see this behaviour if you run the installer?
>

Thanks for your reply; unfortunately, yes, it does. I had refreshed
the installation fairly recently, and running the installer only updated a
few things, not cygwin.dll and not gcc; my installation is the same as
yours. I've tried it with three different shells (tcsh, bash, mksh) and
with both gcc and clang, and all have the same behavior. (Interestingly, if
I compile the example with MSVC and run it in a Cygwin shell, it does _not_
pop up an error dialog box, so presumably it's in the Cygwin runtime,
specifically the definition of __assert_func.)

-- 
William M. (Mike) Miller | Edison Design Group


I see the same behavior as William:

./a.exe < /dev/null > output.txt 2>&1
pops a message box.

gcc (GCC) 10.2.0
CYGWIN_NT-10.0 XXX 3.1.7(0.340/5/3) 2020-08-22 17:48 x86_64 Cygwin
mintty 3.4.1 (x86_64-pc-cygwin)

- André Bleau