Re: GDB 12.0.90 available for testing

[Eli Zaretskii <eliz@gnu.org>]

> From: Andrew Burgess <aburgess@redhat.com>
> Cc: pedro@palves.net, gdb-patches@sourceware.org, brobecker@adacore.com
> Date: Fri, 01 Apr 2022 16:21:35 +0100
> 
> >> So I guess there are problems with making the console input stream
> >> unbuffered, at least on MS-Windows?
> >
> > Or maybe read_command_file shouldn't call setbuf for the same stream
> > repeatedly, but only once?
> 
> I think it must be the former, as far as I can tell with the patch I
> posted we call setbuf just once on stdin (for your -i=mi case).  The
> read_command_file will only be called if you have gdbinit files to read
> in.  You could try adding the -nx and -nh options when starting GDB to
> prevent any gdbinit files being read, but I'd be amazed if that makes a
> difference.

It indeed doesn't.

> Sorry I can't offer more insight.

So what would be the way forward?  The patch below fixes the problem
for me.  But given that Joel says the problem doesn't happen in your
MinGW builds, maybe we shouldn't install it, even for MinGW?  Or
condition it only by symbols available in mingw.org's MingW?

--- gdb/top.c~1	2022-03-28 16:27:31.211375000 +0300
+++ gdb/top.c	2022-04-01 19:12:33.617625000 +0300
@@ -286,6 +286,9 @@ ui::ui (FILE *instream_, FILE *outstream
 {
   buffer_init (&line_buffer);
 
+  if (!ISATTY (instream_))
+    setbuf (instream_, NULL);
+
   if (ui_list == NULL)
     ui_list = this;
   else
@@ -415,6 +418,8 @@ read_command_file (FILE *stream)
 {
   struct ui *ui = current_ui;
 
+  setbuf (stream, nullptr);
+
   scoped_restore save_instream
     = make_scoped_restore (&ui->instream, stream);