Re: gdb fails to flush output (msys2)

[Eli Zaretskii <eliz@gnu.org>]

> Date: Mon, 14 Mar 2022 20:23:40 +0200
> From: Eli Zaretskii <eliz@gnu.org>
> Cc: emacs-devel@gnu.org
> 
> > Starting program: c:\home\juanjo\src\tensor\build-msys2-ucrt64\tests\test_rand.exe 
> > [New Thread 9944.0x1a28]
> > [New Thread 9944.0x28c0]
> > [New Thread 9944.0x3a00]
> > <--- Here it stops. If I press <enter> it shows the console output.
> 
> This seems to indicate that there's some incompatibility between the
> way GDB outputs stuff to its stdout and the device/program which
> displays that stuff.  I don't yet understand well enough what you are
> doing differently from the "usual" use of GDB on MS-Windows (which
> works just fine), so I cannot tell anything more intelligent.  UCRT
> may or may not be a part of the problem, but I don't have any
> experience with using Windows programs linked against UCRT instead of
> MSVCRT.

One possible issue could be with buffering.  Maybe the program you
debug uses line buffering for its output, and that somehow need the
extra Enter?  Just a thought; needless to say, I see no such problems
when I debug from Emacs on.

Can you show how that program behaves when invoked from the system
shell, not under the debugger?  Also, if you invoke "M-x shell" inside
Emacs, and then run that program from the inferior shell, does it
behave correctly, or does it also hangs until you type Enter?