Provide completer for "info registers"

Provide a new completion function for the argument of "info
registers", "info all-registers", and the "lr" command in dbx mode.
Without this patch the default symbol completer is used, which is more
confusing than helpful.

Also add a test for this new feature to "completion.exp": Determine
the target's available set of registers/reggroups and compare this to
the completion of "info registers ".  For determining the available
registers involve the new "maint print user-registers" command.

gdb/ChangeLog:

	* completer.c: Include "target.h", "reggroups.h", and
	"user-regs.h".
	(reg_or_group_completer): New.
	* completer.h (reg_or_group_completer): Declare.
	* infcmd.c (_initialize_infcmd): Set reg_or_group_completer for
	the "info registers" and "info all-registers" commands and the
	dbx-mode "lr" command.

gdb/testsuite/ChangeLog:

	* gdb.base/completion.exp: Add test for completion of "info
	registers ".

1 files changed, 3 insertions, 0 deletions

diff --git a/gdb/completer.h b/gdb/completer.h
index bc7ed96..5e91030 100644
--- a/gdb/completer.h
+++ b/gdb/completer.h
@@ -45,6 +45,9 @@ extern VEC (char_ptr) *command_completer (struct cmd_list_element *,
 extern VEC (char_ptr) *signal_completer (struct cmd_list_element *,
 					 const char *, const char *);
 
+extern VEC (char_ptr) *reg_or_group_completer (struct cmd_list_element *,
+					       const char *, const char *);
+
 extern char *get_gdb_completer_quote_characters (void);
 
 extern char *gdb_completion_word_break_characters (void);