[gdb/tui] Handle tui disable in new ui

  I tried out the following scenario.

First, I start a terminal to get a tty [1].
...
$ gnome-terminal -- bash -c "tty; sleep 999999999" &
...

Then I start gdb, and start a new UI in the tty:
...
$ gdb
(gdb) new-ui console /dev/pts/3
New UI allocated
(gdb)
...

Now I have two terminals, each with a gdb prompt.

I try in the new UI to enable TUI:
...
(gdb) tui enable
❌️ Cannot enable the TUI when the interpreter is 'console'
(gdb)
...
but that is not allowed.

So instead, I enable TUI in the main UI.  So far so good.

Now I disable TUI in the new UI.  That leaves the new UI in this state:
...
(gdb) tui disable
<blinking cursor>
...
So, no gdb prompt.

The main UI does leave TUI, AFAICT.

If I do "print 1<enter>" in the new UI, I get the result in the main UI, which
is not supposed to happen.

Fix this by instead throwing an error if we try to disable TUI in the new UI:
...
(gdb) tui disable
❌️ Cannot enable  or disablethe TUI when the interpreter is 'console'
(gdb)
...

We could try to fix this instead by allowing tui enable/disable from the new
UI, using:
...
  scoped_restore restore_interpreter
    = make_scoped_restore (&current_ui, main_ui);
...
but with just that change, when doing "tui enable" in the new UI we do get a
TUI layout in the main UI, but no gdb prompt.  The prompt does appear after a
new keystroke in the main UI though.

A few more TUI commands (for instance "layout asm") have the same problem:
- they work when entered in the new UI,
- they have an effect in the main UI, but
- they don't show a prompt in the main UI.

I left that problem as is, and exercised some TUI commands in a new UI in the
test-case.

Tested on x86_64-linux.

Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=34035
---
 gdb/testsuite/gdb.tui/new-ui.exp | 93 ++++++++++++++++++++++++++++++++
 gdb/tui/tui.c                    | 18 +++++--
 2 files changed, 107 insertions(+), 4 deletions(-)
 create mode 100644 gdb/testsuite/gdb.tui/new-ui.exp


base-commit: 5ae26f34ef5ac863203d63fffc968d63e823172f
  

On 4/3/26 11:40 AM, Tom de Vries wrote:
> A few more TUI commands (for instance "layout asm") have the same problem:
> - they work when entered in the new UI,
> - they have an effect in the main UI, but
> - they don't show a prompt in the main UI.

I've filed a PR for this problem ( 
https://sourceware.org/bugzilla/show_bug.cgi?id=34040 ).

Thanks,
- Tom
  

On 4/3/26 11:40 AM, Tom de Vries wrote:
> I tried out the following scenario.
> 
> First, I start a terminal to get a tty [1].
> ...
> $ gnome-terminal -- bash -c "tty; sleep 999999999" &
> ...
> 
> Then I start gdb, and start a new UI in the tty:
> ...
> $ gdb
> (gdb) new-ui console /dev/pts/3
> New UI allocated
> (gdb)
> ...
> 
> Now I have two terminals, each with a gdb prompt.
> 
> I try in the new UI to enable TUI:
> ...
> (gdb) tui enable
> ❌️ Cannot enable the TUI when the interpreter is 'console'
> (gdb)
> ...
> but that is not allowed.
> 
> So instead, I enable TUI in the main UI.  So far so good.
> 
> Now I disable TUI in the new UI.  That leaves the new UI in this state:
> ...
> (gdb) tui disable
> <blinking cursor>
> ...
> So, no gdb prompt.
> 
> The main UI does leave TUI, AFAICT.
> 
> If I do "print 1<enter>" in the new UI, I get the result in the main UI, which
> is not supposed to happen.
> 
> Fix this by instead throwing an error if we try to disable TUI in the new UI:
> ...
> (gdb) tui disable
> ❌️ Cannot enable  or disablethe TUI when the interpreter is 'console'
> (gdb)
> ...
> 
> We could try to fix this instead by allowing tui enable/disable from the new
> UI, using:
> ...
>    scoped_restore restore_interpreter
>      = make_scoped_restore (&current_ui, main_ui);
> ...
> but with just that change, when doing "tui enable" in the new UI we do get a
> TUI layout in the main UI, but no gdb prompt.  The prompt does appear after a
> new keystroke in the main UI though.
> 
> A few more TUI commands (for instance "layout asm") have the same problem:
> - they work when entered in the new UI,
> - they have an effect in the main UI, but
> - they don't show a prompt in the main UI.
> 
> I left that problem as is, and exercised some TUI commands in a new UI in the
> test-case.
> 

Ping.

Thanks,
- Tom

> Tested on x86_64-linux.
> 
> Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=34035
> ---
>   gdb/testsuite/gdb.tui/new-ui.exp | 93 ++++++++++++++++++++++++++++++++
>   gdb/tui/tui.c                    | 18 +++++--
>   2 files changed, 107 insertions(+), 4 deletions(-)
>   create mode 100644 gdb/testsuite/gdb.tui/new-ui.exp
> 
> diff --git a/gdb/testsuite/gdb.tui/new-ui.exp b/gdb/testsuite/gdb.tui/new-ui.exp
> new file mode 100644
> index 00000000000..8fe3567077a
> --- /dev/null
> +++ b/gdb/testsuite/gdb.tui/new-ui.exp
> @@ -0,0 +1,93 @@
> +# Copyright 2026 Free Software Foundation, Inc.
> +
> +# This program is free software; you can redistribute it and/or modify
> +# it under the terms of the GNU General Public License as published by
> +# the Free Software Foundation; either version 3 of the License, or
> +# (at your option) any later version.
> +#
> +# This program is distributed in the hope that it will be useful,
> +# but WITHOUT ANY WARRANTY; without even the implied warranty of
> +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +# GNU General Public License for more details.
> +#
> +# You should have received a copy of the GNU General Public License
> +# along with this program.  If not, see <http://www.gnu.org/licenses/>.
> +
> +# Test TUI in combination with a new UI.
> +
> +tuiterm_env
> +
> +# Creating a pty is done on build, and we use it with gdb on host, so we need
> +# build == host, in other words, local host.
> +require {!is_remote host}
> +
> +# Create a pty.
> +spawn -pty
> +set new_ui_spawn_id $spawn_id
> +set new_ui_tty_name $spawn_out(slave,name)
> +
> +set re_cannot_enable_disable_tui \
> +    "Cannot enable or disable the TUI when the interpreter is 'console'"
> +
> +with_test_prefix main-ui {
> +    Term::clean_restart 24 80
> +
> +    # Check that we cannot setup a new tui UI.  Also checked in
> +    # gdb.base/new-ui.exp.
> +    gdb_test "new-ui tui $new_ui_tty_name" \
> +	"interpreter 'tui' cannot be used with a new UI" \
> +	{new-ui tui $new_ui_tty_name}
> +
> +    # Set up a new console UI.
> +    gdb_test "new-ui console $new_ui_tty_name" \
> +	"New UI allocated" \
> +	{new-ui cli $new_ui_tty_name}
> +}
> +
> +with_test_prefix new-ui {
> +    with_spawn_id $new_ui_spawn_id {
> +	# Check that we cannot enable TUI in the new UI.
> +	gdb_test "tui enable" $re_cannot_enable_disable_tui
> +    }
> +}
> +
> +with_test_prefix main-ui {
> +    if {![Term::enter_tui]} {
> +	unsupported "TUI not supported"
> +	return
> +    }
> +}
> +
> +with_test_prefix new-ui {
> +    with_spawn_id $new_ui_spawn_id {
> +	# Check that we cannot disable TUI in the new UI.
> +	# Regression test for PR34035.  Without the fix, this test will timeout,
> +	# because no prompt will appear.
> +	gdb_test "tui disable" $re_cannot_enable_disable_tui
> +
> +	gdb_test "print 1" \
> +	    [quotemeta {$@DECIMAL = 1}] \
> +	    "Check that UI is responsive"
> +    }
> +
> +    # Try out some TUI commands.  We don't check for the effect in the main
> +    # UI, we just check that the main UI is still responsive at the end.
> +    with_spawn_id $new_ui_spawn_id {
> +	gdb_test "info win" [quotemeta "@...(has focus)@..."]
> +
> +	gdb_test "focus cmd" \
> +	    [string_to_regexp "Focus set to cmd window."]
> +
> +	# This command leaves a blinking cursor at the end of the status line.
> +	gdb_test_no_output "layout asm"
> +
> +	gdb_test "winheight asm +1"
> +	gdb_test_no_output "tui refresh"
> +    }
> +}
> +
> +with_test_prefix main-ui {
> +    gdb_assert {[Term::command "print 1"]} \
> +	"Check that UI is responsive"
> +    Term::dump_screen
> +}
> diff --git a/gdb/tui/tui.c b/gdb/tui/tui.c
> index 9cf21f390c8..5e39eef71c6 100644
> --- a/gdb/tui/tui.c
> +++ b/gdb/tui/tui.c
> @@ -394,6 +394,17 @@ gdb_getenv_term (void)
>     return "<unset>";
>   }
>   
> +/* Error out if the toplevel interpreter is not the TUI interpreter.  */
> +
> +static void
> +require_tui_interpreter ()
> +{
> +  const char *interp = top_level_interpreter ()->name ();
> +  if (!streq (interp, INTERP_TUI))
> +    error (_("Cannot enable or disable the TUI when the interpreter is '%s'"),
> +	   interp);
> +}
> +
>   /* Enter in the tui mode (curses).
>      When in normal mode, it installs the tui hooks in gdb, redirects
>      the gdb output, configures the readline to work in tui mode.
> @@ -424,13 +435,10 @@ tui_enable (void)
>   #ifndef __MINGW32__
>          const char *cap;
>   #endif
> -      const char *interp;
>   
>         /* If the top level interpreter is not the console/tui (e.g.,
>   	 MI), enabling curses will certainly lose.  */
> -      interp = top_level_interpreter ()->name ();
> -      if (!streq (interp, INTERP_TUI))
> -	error (_("Cannot enable the TUI when the interpreter is '%s'"), interp);
> +      require_tui_interpreter ();
>   
>         /* Don't try to setup curses (and print funny control
>   	 characters) if we're not outputting to a terminal.  */
> @@ -556,6 +564,8 @@ tui_disable (void)
>     if (!tui_active)
>       return;
>   
> +  require_tui_interpreter ();
> +
>     /* Restore initial readline keymap.  */
>     rl_set_keymap (tui_readline_standard_keymap);
>   
> 
> base-commit: 5ae26f34ef5ac863203d63fffc968d63e823172f