gdb: Add command completers for some info commands

Add command completion for info variables, functions, args, and
locals.  This completer only completes the command line options as
these commands all take a regexp which GDB can't really offer
completions for.

gdb/ChangeLog:

	* cli/cli-utils.c (info_print_command_completer): New function.
	* cli/cli-utils.h: Add 'completer.h' include, and forward
	declaration for 'struct cmd_list_element'.
	(info_print_command_completer): Declare.
	* stack.c (_initialize_stack): Add completer for 'info locals' and
	'info args'.
	* symtab.c (_initialize_symtab): Add completer for 'info
	variables' and 'info functions'.
	* NEWS: Mention completion for additional info commands.

2 files changed, 30 insertions, 0 deletions

diff --git a/gdb/cli/cli-utils.c b/gdb/cli/cli-utils.c
index cd3dfe6..c640550 100644
--- a/gdb/cli/cli-utils.c
+++ b/gdb/cli/cli-utils.c
@@ -473,3 +473,20 @@ extract_info_print_options (info_print_options *opts,
   if (*args != nullptr && **args == '\0')
     *args = nullptr;
 }
+
+/* See documentation in cli-utils.h.  */
+
+void
+info_print_command_completer (struct cmd_list_element *ignore,
+			      completion_tracker &tracker,
+			      const char *text, const char * /* word */)
+{
+  const auto group
+    = make_info_print_options_def_group (nullptr);
+  if (gdb::option::complete_options
+      (tracker, &text, gdb::option::PROCESS_OPTIONS_UNKNOWN_IS_OPERAND, group))
+    return;
+
+  const char *word = advance_to_expression_complete_word_point (tracker, text);
+  symbol_completer (ignore, tracker, text, word);
+}
diff --git a/gdb/cli/cli-utils.h b/gdb/cli/cli-utils.h
index a3826be..17cdd84 100644
--- a/gdb/cli/cli-utils.h
+++ b/gdb/cli/cli-utils.h
@@ -20,6 +20,10 @@
 #ifndef CLI_CLI_UTILS_H
 #define CLI_CLI_UTILS_H
 
+#include "completer.h"
+
+struct cmd_list_element;
+
 /* *PP is a string denoting a number.  Get the number.  Advance *PP
    after the string and any trailing whitespace.
 
@@ -66,6 +70,15 @@ struct info_print_options
 extern void extract_info_print_options (info_print_options *opts,
 					const char **args);
 
+/* Function that can be used as a command completer for 'info variable'
+   and friends.  This offers command option completion as well as symbol
+   completion.  At the moment all symbols are offered for all commands.  */
+
+extern void info_print_command_completer (struct cmd_list_element *ignore,
+					  completion_tracker &tracker,
+					  const char *text,
+					  const char * /* word */);
+
 /* Throws an error telling the user that ARGS starts with an option
    unrecognized by COMMAND.  */