De : Cygwin <cygwin-boun...@cygwin.com> de la part de Thomas Wolff <redacted>
Envoyé : 19 novembre 2020 13:30
À : cygwin@cygwin.com <cygwin@cygwin.com>
Objet : Re: Failed assertion dialog box ATTN: Takashi Yano
---------------------------------------------------------------------------------------
Am 19.11.2020 um 15:21 schrieb André Bleau via Cygwin:
> ...
> Here's some more info:
>
> It seems the bug is related to pseudo-console support; that explains why it
> is Windows 10 specific.
>
> Experiment:
>
> CYGWIN=disable_pcon /usr/bin/mintty &
>
> In the newly created window:
>
> $ ./a.exe </dev/null >output.txt 2>&1
> Aborted (core dumped)
>
> No message box popup.
>
> $ cat output.txt
> assertion "false" failed: file "assert.cpp", line 3, function: int main()
>
> In the original mintty window, with empty CYGWIN env variable:
>
> $ ./a.exe </dev/null >output.txt 2>&1
> Aborted (core dumped)
>
> A message box pops
>
> AND:
>
> $ cat output.txt
>
> output.txt is empty
>
> So, 2 problems here.
>
> In a CMD Window:
>
> set path=%PATH%D:\Cygwin\bin;
> a.exe <NUL: >outcmd.txt 2>&1
> 1 [main] a 759 cygwin_exception::open_stackdumpfile: Dumping stack
>trace to a.exe.stackdump
>
> type outcmd.txt
> assertion "false" failed: file "assert.cpp", line 3, function: int main()
> 1 [main] a 759 cygwin_exception::open_stackdumpfile: Dumping stack
>trace to a.exe.stackdump
>
> The bug could be in cygwin or in mintty. Maybe this is something that Thomas
> Wolff (mintty author) or Takashi Yano (pseudo-console support expert) would
> want to look at.
> ---------------------------------------------------------------------------------------
>
> OK, I opened an issue for mintty and it was quickly closed with that quote:
>
> "Quick generic answer: if it's caused by ConPTY support, it's not related to
> mintty; also mintty never shows any popups.
> Funny thing, though, but really: assert isn't handled by the terminal."
>
> So the issue can only be with pseudo-console support in cygwin.
It does not seem to happen in xterm which is weird.
It does however also happen in rxvt-unicode, xfce4-terminal, and vte.
The message text of the popup can be easily found in cygwin code.
Thomas
---------------------------------------------------------------------------------------
One more data point:
The following program:
$ cat stderr.c
#include <stdio.h>
int main() {
fprintf(stdout, "To stdout\n");
fprintf(stderr, "To stderr\n");
return 0;
}
$ gcc stderr.c
$ ./a.exe </dev/null >output.txt 2>&1
Behaves normally, with either empty CYGWIN env variable or with
$ CYGWIN=disable_pcon /usr/bin/mintty &
So the problem is narrowly confined to how Cygwin handles assert when
pseudo-console is used and stdin, stdout, and stderr are redirected. Not in all
cases where pseudo-console is used and stdin, stdout, and stderr are
redirected.
- André Bleau
--
Problem reports: https://cygwin.com/problems.html
FAQ: https://cygwin.com/faq/
Documentation: https://cygwin.com/docs.html
Unsubscribe info: https://cygwin.com/ml/#unsubscribe-simple
