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From: Bart Schaefer <schaefer@brasslantern.com>
Message-id: <110228200011.ZM7304@torch.brasslantern.com>
Date: Mon, 28 Feb 2011 20:00:11 -0800
In-reply-to: <20110228094931.7deaa547@pwslap01u.europe.root.pri>
Comments: In reply to Peter Stephenson <Peter.Stephenson@csr.com>
 "Re: Crash bug in typeset -T" (Feb 28,  9:49am)
References: <110227223740.ZM5361@torch.brasslantern.com>
	<20110228094931.7deaa547@pwslap01u.europe.root.pri>
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To: <zsh-workers@zsh.org>
Subject: Re: Crash bug in typeset -T
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On Feb 28,  9:49am, Peter Stephenson wrote:
} Subject: Re: Crash bug in typeset -T
}
} On Sun, 27 Feb 2011 22:37:40 -0800
} Bart Schaefer <schaefer@brasslantern.com> wrote:
} > Obviously "typeset -T" needs to check if it's being applied to a
} > parameter that's already tied ... but what should it do in that
} > case?  Error?
} 
} Within looking in any detail, I think it's going to have to be an error.

OK, patch below does this, and improves a couple of other error messages.

Turns out that it's only necessary to check the scalar; if the array
is being re-tied, re-creating it unsets the original scalar.  This is
fortunate because the code never retrieves the paramtab node for the
array.

} The reason you need to unset variables to retie them is that undoing it
} is a lot of tricky code all over the place creating messy special cases.

Seems as though bin_typeset() could save the values, unset the scalar
(which has the side-effect of unsetting the array), and then recreate
both parameters.  However, I haven't attempted to do that.

--- Src/builtin.c.~1.247.~	2011-02-27 10:21:53.000000000 -0800
+++ Src/builtin.c	2011-02-28 19:55:09.000000000 -0800
@@ -2420,12 +2420,12 @@
 	}
 	if (!strcmp(asg0.name, asg->name)) {
 	    unqueue_signals();
-	    zerrnam(name, "can't tie a variable to itself");
+	    zerrnam(name, "can't tie a variable to itself: %s", asg0.name);
 	    return 1;
 	}
 	if (strchr(asg0.name, '[') || strchr(asg->name, '[')) {
 	    unqueue_signals();
-	    zerrnam(name, "can't tie array elements");
+	    zerrnam(name, "can't tie array elements: %s", asg0.name);
 	    return 1;
 	}
 	/*
@@ -2440,6 +2440,11 @@
 	if ((pm = (Param) paramtab->getnode(paramtab, asg0.name))
 	    && !(pm->node.flags & PM_UNSET)
 	    && (locallevel == pm->level || !(on & PM_LOCAL))) {
+	    if (pm->node.flags & PM_TIED) {
+		unqueue_signals();
+		zerrnam(name, "can't tie already tied scalar: %s", asg0.name);
+		return 1;
+	    }
 	    if (!asg0.value && !(PM_TYPE(pm->node.flags) & (PM_ARRAY|PM_HASHED)))
 		oldval = ztrdup(getsparam(asg0.name));
 	    on |= (pm->node.flags & PM_EXPORTED);