[patch] Fix PR c++/17456: Infinite loop after error in convert_to_void

[Volker Reichelt]

When compiling the following invalid code snippet

========================================
struct A {};

struct B : A
{
    void foo();
    B() { foo; }
};
========================================

the 3.3-branch compiler gets into a memory-eating infinite loop after
issuing a sensible error message. The following patch fixes that by
setting expr to void_zero_node after the failure (like 3.4 branch
and mainline).

Bootstrapped and regtested on the 3.3 branch (i686-pc-linux-gnu).
Gaby, ok to commit?

Regards,
Volker


2004-12-16  Volker Reichelt  <reichelt@igpm.rwth-aachen.de>

	* cvt.c (convert_to_void): Set expr to void_zero_node after
	overload failure.


Index: gcc/gcc/cp/cvt.c
===================================================================
--- gcc/gcc/cp/cvt.c	23 Feb 2004 12:50:50 -0000	1.126.2.4
+++ gcc/gcc/cp/cvt.c	17 Dec 2004 23:36:48 -0000
@@ -903,6 +903,7 @@ convert_to_void (expr, implicit)
 	   of an overloaded function, and this is not one of them.  */
 	pedwarn ("%s cannot resolve address of overloaded function",
 		    implicit ? implicit : "void cast");
+	expr = void_zero_node;
       }
     else if (implicit && probe == expr && is_overloaded_fn (probe))
       /* Only warn when there is no &.  */
===================================================================