Fixes a bug in a previous patch of mine, more_than_3_match_items.patch.txt,
reported by David Larson (davidlarson at ti dot com) on the Vim development
mailing list, July 26, 2007.  The report:

    matchadd() produces a runtime error. To reproduce:

    :highlight MyGroup ctermbg=green guibg=green
    :let m = matchadd("MyGroup", "TODO")
    :let m = matchadd("MyGroup", "name")

    E685: Internal error: get_tv_number()

I didn't discover the bug while writing the original patch, as the bug only
occurs on my machine when running gvim and not compiling with -g.

Solution: In matchadd(), check the third argument to be present before using
the fourth argument.

Created by Martin Toft <mt@martintoft.dk> during Google Summer of Code 2007.


Index: src/eval.c
===================================================================
RCS file: /cvsroot/vim/vim7/src/eval.c,v
retrieving revision 1.220
diff -c -r1.220 eval.c
*** src/eval.c	26 Jul 2007 20:58:42 -0000	1.220
--- src/eval.c	27 Jul 2007 14:55:54 -0000
***************
*** 12526,12534 ****
      if (grp == NULL || pat == NULL)
  	return;
      if (argvars[2].v_type != VAR_UNKNOWN)
  	prio = get_tv_number_chk(&argvars[2], &error);
!     if (argvars[3].v_type != VAR_UNKNOWN)
! 	id = get_tv_number_chk(&argvars[3], &error);
      if (error == TRUE)
  	return;
      if (id >= 1 && id <= 3)
--- 12526,12536 ----
      if (grp == NULL || pat == NULL)
  	return;
      if (argvars[2].v_type != VAR_UNKNOWN)
+     {
  	prio = get_tv_number_chk(&argvars[2], &error);
! 	if (argvars[3].v_type != VAR_UNKNOWN)
! 	    id = get_tv_number_chk(&argvars[3], &error);
!     }
      if (error == TRUE)
  	return;
      if (id >= 1 && id <= 3)