gdb: make add_com_alias accept target as a cmd_list_element

The alias creation functions currently accept a name to specify the
target command.  They pass this to add_alias_cmd, which needs to lookup
the target command by name.

Given that:

 - We don't support creating an alias for a command before that command
   exists.
 - We always use add_info_alias just after creating that target command,
   and therefore have access to the target command's cmd_list_element.

... change add_com_alias to accept the target command as a
cmd_list_element (other functions are done in subsequent patches).  This
ensures we don't create the alias before the target command, because you
need to get the cmd_list_element from somewhere when you call the alias
creation function.  And it avoids an unecessary command lookup.  So it
seems better to me in every aspect.

gdb/ChangeLog:

	* command.h (add_com_alias): Accept target as
	cmd_list_element.  Update callers.

Change-Id: I24bed7da57221cc77606034de3023fedac015150

1 files changed, 15 insertions, 13 deletions

diff --git a/gdb/stack.c b/gdb/stack.c
index 334d974..a3a6ba6 100644
--- a/gdb/stack.c
+++ b/gdb/stack.c
@@ -3329,22 +3329,24 @@ An argument says how many frames up to go."));
 Same as the `up' command, but does not print anything.\n\
 This is useful in command scripts."));
 
-  add_com ("down", class_stack, down_command, _("\
+  cmd_list_element *down_cmd
+    = add_com ("down", class_stack, down_command, _("\
 Select and print stack frame called by this one.\n\
 An argument says how many frames down to go."));
-  add_com_alias ("do", "down", class_stack, 1);
-  add_com_alias ("dow", "down", class_stack, 1);
+  add_com_alias ("do", down_cmd, class_stack, 1);
+  add_com_alias ("dow", down_cmd, class_stack, 1);
   add_com ("down-silently", class_support, down_silently_command, _("\
 Same as the `down' command, but does not print anything.\n\
 This is useful in command scripts."));
 
-  add_prefix_cmd ("frame", class_stack,
-		  &frame_cmd.base_command, _("\
+  cmd_list_element *frame_cmd_el
+    = add_prefix_cmd ("frame", class_stack,
+		      &frame_cmd.base_command, _("\
 Select and print a stack frame.\n\
 With no argument, print the selected stack frame.  (See also \"info frame\").\n\
 A single numerical argument specifies the frame to select."),
-		  &frame_cmd_list, 1, &cmdlist);
-  add_com_alias ("f", "frame", class_stack, 1);
+		      &frame_cmd_list, 1, &cmdlist);
+  add_com_alias ("f", frame_cmd_el, class_stack, 1);
 
 #define FRAME_APPLY_OPTION_HELP "\
 Prints the frame location information followed by COMMAND output.\n\
@@ -3498,14 +3500,14 @@ For backward compatibility, the following qualifiers are supported:\n\
 With a negative COUNT, print outermost -COUNT frames."),
 			       backtrace_opts);
 
-  cmd_list_element *c = add_com ("backtrace", class_stack,
-				 backtrace_command,
-				 backtrace_help.c_str ());
-  set_cmd_completer_handle_brkchars (c, backtrace_command_completer);
+  cmd_list_element *backtrace_cmd
+    = add_com ("backtrace", class_stack, backtrace_command,
+	       backtrace_help.c_str ());
+  set_cmd_completer_handle_brkchars (backtrace_cmd, backtrace_command_completer);
 
-  add_com_alias ("bt", "backtrace", class_stack, 0);
+  add_com_alias ("bt", backtrace_cmd, class_stack, 0);
 
-  add_com_alias ("where", "backtrace", class_stack, 0);
+  add_com_alias ("where", backtrace_cmd, class_stack, 0);
   add_info ("stack", backtrace_command,
 	    _("Backtrace of the stack, or innermost COUNT frames."));
   add_info_alias ("s", "stack", 1);