diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 9e3acb9c7c6d..3f32ba487d27 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,7 @@
+2004-10-02  Joseph S. Myers  <jsm@polyomino.org.uk>
+
+	* c-typeck.c (warn_for_assignment): Don't permit argnum == 0.
+
 2004-10-01  Ulrich Weigand  <uweigand@de.ibm.com>
 
 	* config/s390/s390-protos.h (s390_comparison): Add prototype.
diff --git a/gcc/c-typeck.c b/gcc/c-typeck.c
index 70d39389fa8d..08b5953a9038 100644
--- a/gcc/c-typeck.c
+++ b/gcc/c-typeck.c
@@ -3720,8 +3720,7 @@ c_convert_parm_for_inlining (tree parm, tree value, tree fn, int argnum)
 
 /* Print a warning using MSGID.
    It gets OPNAME as its one parameter.
-   if OPNAME is null and ARGNUM is 0, it is replaced by "passing arg of `FUNCTION'".
-   Otherwise if OPNAME is null, it is replaced by "passing arg ARGNUM of `FUNCTION'".
+   If OPNAME is null, it is replaced by "passing arg ARGNUM of 'FUNCTION'".
    FUNCTION and ARGNUM are handled specially if we are building an
    Objective-C selector.  */
 
@@ -3739,26 +3738,8 @@ warn_for_assignment (const char *msgid, const char *opname, tree function,
 	  function = selector;
 	  argnum -= 2;
 	}
-      if (argnum == 0)
-	{
-	  if (function)
-	    {
-	      /* Function name is known; supply it.  */
-	      const char *const argstring = _("passing arg of '%s'");
-	      new_opname = (char *) alloca (IDENTIFIER_LENGTH (function)
-				   + strlen (argstring) + 1 + 1);
-	      sprintf (new_opname, argstring,
-		       IDENTIFIER_POINTER (function));
-	    }
-	  else
-	    {
-	      /* Function name unknown (call through ptr).  */
-	      const char *const argnofun = _("passing arg of pointer to function");
-	      new_opname = (char *) alloca (strlen (argnofun) + 1 + 1);
-	      sprintf (new_opname, argnofun);
-	    }
-	}
-      else if (function)
+      gcc_assert (argnum > 0);
+      if (function)
 	{
 	  /* Function name is known; supply it.  */
 	  const char *const argstring = _("passing arg %d of '%s'");