Pierre Muller wrote:
> I tried to expose some cygwin testsuite problems
> related to the fact that dejagnu does not seem
> to be able to fool the cygwin system, to
> get it to believe that the output is not redirected.
> 
> http://sourceware.org/ml/gdb/2007-11/msg00273.html
> 
>   The main effect is that, Cygwin knowing that 
> the output is redirected to a non-tty, it will start
> to use file buffering that will interact badly
> with the expectation of the gdb testsuite.
> 

I don't think that dejagnu is to blame here, and
I believe the individual testfiles are the wrong place
to fix this.  You can easily reproduce the symptoms
in any run.  Try this with the attached patch:

#include <stdio.h>
#include <stdlib.h>

int main ()
{
         printf ("isatty 0 = %d\n", isatty (0));
         printf ("isatty 1 = %d\n", isatty (1));
         printf ("isatty 2 = %d\n", isatty (2));
         return 0;
}


--------------------

Cygwin host:

 >./main.exe
isatty 0 = 1
isatty 1 = 1
isatty 2 = 1

 >gdb main.exe
isatty (0) = 1
isatty (1) = 1
isatty (2) = 1
ttyname (0) = /dev/tty2
ttyname (1) = /dev/tty2
ttyname (2) = /dev/tty2
GNU gdb 6.7.50.20071201-cvs
Copyright (C) 2007 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "i686-pc-cygwin"...
(gdb) r
Starting program: /home/pedro/isatty/main.exe
isatty 0 = 0
isatty 1 = 0
isatty 2 = 0

Program exited normally.
(gdb)


Notice the "isatty $x = 0", and contrast
with:

-------------

Linux host:

 >./main
isatty 0 = 1
isatty 1 = 1
isatty 2 = 1

 >gdb ./main
isatty (0) = 1
isatty (1) = 1
isatty (2) = 1
ttyname (0) = /dev/pts/5
ttyname (1) = /dev/pts/5
ttyname (2) = /dev/pts/5
GNU gdb 6.7.50.20071204-cvs
Copyright (C) 2007 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "i686-pc-linux-gnu"...
(gdb) r
Starting program: /home/pedro/isatty/main
isatty 0 = 1
isatty 1 = 1
isatty 2 = 1

Program exited normally.
(gdb)

-------------

I don't know enough of the Cygwin tty support,
but I would expect that if gdb had a (Windows) console
attached (bash started from cmd.exe, not the xterm or rxvt),
the inferior would inherit it, and the runtime would arrange
for the isatty to be true, but that doesn't seem to hold.
Neither CYGWIN=tty nor 'set new-group 0' seemed to help.
This probably has something to do with starting the inferior
with CreateProcess in win32-nat.c:win32_create_inferior.

-- 
Pedro Alves