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PATCH: tied parameters bug

I noticed this bug while looking at aspects of the parameter code:

% g() {
>   local SC="hello"
>   unset sc
> }
% typeset -T SC sc
% g

Tied parameters use pm->ename to store the name of the parameter they
are tied to in string form. So in this code, it unsets the local
instead of the global SC. As a result, the global SC still exists and
if used, fairly shortly results in a seg fault. The same problem
applies the other way around (unsetting the scalar with a local array).

The fix below relies on the tied parameters being at the same local
level (which I believe always holds true). It makes the code search for
the parameter at the correct local level and then unsets it which
requires a nasty hack to avoid the parameter node being removed from
the table.


Index: Src/params.c
RCS file: /cvsroot/zsh/zsh/Src/params.c,v
retrieving revision 1.65
diff -u -r1.65 params.c
--- Src/params.c	5 Aug 2002 12:36:00 -0000	1.65
+++ Src/params.c	8 Oct 2002 09:26:44 -0000
@@ -2234,8 +2234,21 @@
     /* remove it under its alternate name if necessary */
     if (pm->ename && !altflag) {
 	altpm = (Param) paramtab->getnode(paramtab, pm->ename);
-	if (altpm)
+	/* tied parameters are at the same local level as each other */
+	oldpm = NULL;
+	while (altpm && altpm->level > pm->level) {
+	    /* param under alternate name hidden by a local */
+	    oldpm = altpm;
+	    altpm = altpm->old;
+	}
+	if (altpm) {
+	    if (oldpm) {
+		oldpm->old = altpm->old;
+		/* fudge things so removenode isn't called */
+		altpm->level = locallevel;
+	    }
 	    unsetparam_pm(altpm, 1, exp);
+	}

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