Add max-completions parameter, and implement tab-completion limiting.

This commit adds a new exception, MAX_COMPLETIONS_REACHED_ERROR, to be
thrown whenever the completer has generated too many candidates to
be useful.  A new user-settable variable, "max_completions", is added
to control this behaviour.  A top-level completion limit is added to
complete_line_internal, as the final check to ensure the user never
sees too many completions.  An additional limit is added to
default_make_symbol_completion_list_break_on, to halt time-consuming
symbol table expansions.

gdb/ChangeLog:

	PR cli/9007
	PR cli/11920
	PR cli/15548
	* cli/cli-cmds.c (complete_command): Notify user if max-completions
	reached.
	* common/common-exceptions.h (enum errors)
	<MAX_COMPLETIONS_REACHED_ERROR>: New value.
	* completer.h (get_max_completions_reached_message): New declaration.
	(max_completions): Likewise.
	(completion_tracker_t): New typedef.
	(new_completion_tracker): New declaration.
	(make_cleanup_free_completion_tracker): Likewise.
	(maybe_add_completion_enum): New enum.
	(maybe_add_completion): New declaration.
	(throw_max_completions_reached_error): Likewise.
	* completer.c (max_completions): New global variable.
	(new_completion_tracker): New function.
	(free_completion_tracker): Likewise.
	(make_cleanup_free_completion_tracker): Likewise.
	(maybe_add_completions): Likewise.
	(throw_max_completions_reached_error): Likewise.
	(complete_line): Remove duplicates and limit result to max_completions
	entries.
	(get_max_completions_reached_message): New function.
	(gdb_display_match_list): Handle max_completions.
	(_initialize_completer): New declaration and function.
	* symtab.c: Include completer.h.
	(completion_tracker): New static variable.
	(completion_list_add_name): Call maybe_add_completion.
	(default_make_symbol_completion_list_break_on_1): Renamed from
	default_make_symbol_completion_list_break_on.  Maintain
	completion_tracker across calls to completion_list_add_name.
	(default_make_symbol_completion_list_break_on): New function.
	* top.c (init_main): Set rl_completion_display_matches_hook.
	* tui/tui-io.c: Include completer.h.
	(tui_old_rl_display_matches_hook): New static global.
	(tui_rl_display_match_list): Notify user if max-completions reached.
	(tui_setup_io): Save/restore rl_completion_display_matches_hook.
	* NEWS (New Options): Mention set/show max-completions.

gdb/doc/ChangeLog:

	* gdb.texinfo (Command Completion): Document new
	"set/show max-completions" option.

gdb/testsuite/ChangeLog:

	* gdb.base/completion.exp: Disable completion limiting for
	existing tests.  Add new tests to check completion limiting.
	* gdb.linespec/ls-errs.exp: Disable completion limiting.

1 files changed, 3 insertions, 1 deletions

diff --git a/gdb/tui/tui-io.c b/gdb/tui/tui-io.c
index 831705c..2b5a166 100644
--- a/gdb/tui/tui-io.c
+++ b/gdb/tui/tui-io.c
@@ -132,6 +132,7 @@ static rl_getc_func_t *tui_old_rl_getc_function;
 static rl_voidfunc_t *tui_old_rl_redisplay_function;
 static rl_vintfunc_t *tui_old_rl_prep_terminal;
 static rl_voidfunc_t *tui_old_rl_deprep_terminal;
+static rl_compdisp_func_t *tui_old_rl_display_matches_hook;
 static int tui_old_rl_echoing_p;
 
 /* Readline output stream.
@@ -468,6 +469,7 @@ tui_setup_io (int mode)
       tui_old_rl_deprep_terminal = rl_deprep_term_function;
       tui_old_rl_prep_terminal = rl_prep_term_function;
       tui_old_rl_getc_function = rl_getc_function;
+      tui_old_rl_display_matches_hook = rl_completion_display_matches_hook;
       tui_old_rl_outstream = rl_outstream;
       tui_old_rl_echoing_p = _rl_echoing_p;
       rl_redisplay_function = tui_redisplay_readline;
@@ -511,8 +513,8 @@ tui_setup_io (int mode)
       rl_deprep_term_function = tui_old_rl_deprep_terminal;
       rl_prep_term_function = tui_old_rl_prep_terminal;
       rl_getc_function = tui_old_rl_getc_function;
+      rl_completion_display_matches_hook = tui_old_rl_display_matches_hook;
       rl_outstream = tui_old_rl_outstream;
-      rl_completion_display_matches_hook = 0;
       _rl_echoing_p = tui_old_rl_echoing_p;
       rl_already_prompted = 0;