gdb patch to suppress empty lines, re-visited

[Per Bothner <per@bothner.com>]

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This is a revision of a patch originally from 1999:
http://sources.redhat.com/ml/gdb-patches/1999-q2/msg00093.html

I'm not sure if the patch in top.c does anything, since I don't
know when/if readline is called from command_line_input.

OK to check in? With or without the top.c change?
-- 
	--Per Bothner
per@bothner.com   http://www.bothner.com/per/

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Index: top.c
===================================================================
RCS file: /cvs/src/src/gdb/top.c,v
retrieving revision 1.68
diff -u -p -r1.68 top.c
--- top.c	26 Sep 2002 17:46:04 -0000	1.68
+++ top.c	7 Dec 2002 06:21:11 -0000
@@ -1211,7 +1211,12 @@ command_line_input (char *prompt_arg, in
 	}
       else if (command_editing_p && instream == stdin && ISATTY (instream))
 	{
+	  int can_repeat = repeat && *line != NULL;
+	  if (can_repeat)
+	    rl_erase_empty_line++;
 	  rl = gdb_readline_wrapper (local_prompt);
+	  if (can_repeat)
+	    rl_erase_empty_line--;
 	}
       else
 	{
Index: event-top.c
===================================================================
RCS file: /cvs/src/src/gdb/event-top.c,v
retrieving revision 1.24
diff -u -p -r1.24 event-top.c
--- event-top.c	5 Nov 2002 22:38:11 -0000	1.24
+++ event-top.c	7 Dec 2002 06:21:12 -0000
@@ -191,6 +191,7 @@ cli_command_loop (void)
       strcpy (a_prompt, PREFIX (0));
       strcat (a_prompt, gdb_prompt);
       strcat (a_prompt, SUFFIX (0));
+      rl_erase_empty_line = *line != NULL;
       rl_callback_handler_install (a_prompt, input_handler);
     }
   else
@@ -296,6 +297,7 @@ display_gdb_prompt (char *new_prompt)
   if (async_command_editing_p)
     {
       rl_callback_handler_remove ();
+      rl_erase_empty_line = *line != NULL;
       rl_callback_handler_install (new_prompt, input_handler);
     }
   /* new_prompt at this point can be the top of the stack or the one passed in */