[RFA] Fix bug in add_alias_cmd

["Pierre Muller" <muller at ics dot u-strasbg dot fr>]

  Out of curiosity, I tried to start
gdb with --xdb options to see the special
options that this provides.

  I got this:
$ ./gdb -xdb
../../purecvs/gdb/cli/cli-decode.c:255: internal-error: add_alias_cmd:
Assertion
 `!aliases && !prehook && prehookee && !posthook && ! posthookee' failed.
A problem internal to GDB has been detected,
further debugging may prove unreliable.
Quit this debugging session? (y or n) [answered Y; input not from terminal]
../../purecvs/gdb/cli/cli-decode.c:255: internal-error: add_alias_cmd:
Assertion
 `!aliases && !prehook && prehookee && !posthook && ! posthookee' failed.
A problem internal to GDB has been detected,
further debugging may prove unreliable.
Create a core file of GDB? (y or n) [answered Y; input not from terminal]
Aborted (core dumped)

  This is due to "bu" being an alias command of "ubreak"
for xdb options, but "ubreak" doesn't seem to exist anywhere
and I found no trace of it anywhere is the sources :(

I fact after looking at the sources, it appears to me
that the assertion itself is wrong.
prehookee should also be NULL, as the other pointers tested.


This small patch fixes it.

Tested on complier farm without regression.

OK to commit?


Pierre Muller
Pascal language support maintainer for GDB

PS: What should we do about 
Could I also remove that line 
 if (xdb_commands)
    {
      add_com_alias ("ba", "break", class_breakpoint, 1);
      add_com_alias ("bu", "ubreak", class_breakpoint, 1);
    }


2009-06-06  Pierre Muller  <muller@ics.u-strasbg.fr>

	* cli/cli-decode.c (add_alias_cmd): Correct assertion.

Index: src/gdb/cli/cli-decode.c
===================================================================
RCS file: /cvs/src/src/gdb/cli/cli-decode.c,v
retrieving revision 1.79
diff -u -p -r1.79 cli-decode.c
--- src/gdb/cli/cli-decode.c	12 May 2009 16:51:13 -0000	1.79
+++ src/gdb/cli/cli-decode.c	6 Jun 2009 11:18:08 -0000
@@ -251,7 +251,7 @@ add_alias_cmd (char *name, char *oldname
 						     &prehook, &prehookee,
 						     &posthook,
&posthookee);
       /* If this happens, it means a programmer error somewhere.  */
-      gdb_assert (!aliases && !prehook && prehookee
+      gdb_assert (!aliases && !prehook && !prehookee
 		  && !posthook && ! posthookee);
       return 0;
     }