[RFA] new set/show multiple-choice-auto-select commands

[Joel Brobecker <brobecker at adacore dot com>]

Hello,

The user sometimes enters an expression which is ambiguous. For instance,
the name of a function or a variable which has homonyms... In that case,
the debugger is expected to display the list of possibilities and ask
the user to choose which one he meant (with an additional 2 possible
choices: "all" and "cancel").

This has been a very practical solution when in interactive mode
(ie when a user is driving the session), but an annoyance when driving
the debugger with a tool. So we added a new set/show command that
allowed the user to configure the behavior of the debugger so that:
  1. Either the menu is still displayed (default behavior);
  2. The choice "all" is always automatically selected;
  3. The choice "cancel" is always automatically selected.
Some of the AdaCore engineers actually disliked the menu and started
using this new command to always select all options, even in
interactive mode.

The syntax is as follow:

        (gdb) set multiple-choice-auto-select (off|all|cancel)
        (gdb) show multiple-choice-auto-select

As said above, the default is "off", which preserves the current
behavior by default.

The reason why I am proposing this as an RFA is that I'm wondering
if others might be interested in sharing this setting. I noticed
from a comment that Paul wrote that menus are also printed by
linespec:decode_line_2. Otherwise, I'm happy to keep it in ada-lang.c
(less work for me :-).

2008-01-01  Joel Brobecker  <brobecker@adacore.com>

        * ada-lang.c (auto_select_off, auto_select_all, auto_select_cancel)
        (auto_select_choices, auto_select_choice): New static global variables.
        (user_select_syms): Add handling of new multiple-choice-auto-select
        setting.
        (_initialize_ada_language): Add new multiple-choice-auto-select option.

Tested on x86-linux. No regression.

A testcase and documentation will follow as soon as we agree on
the patch itself.

Thoughts?

Thanks,
-- 
Joel

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