re PR c++/30847 (ICE with invalid statement expression)

	PR c++/30847
	* typeck.c (build_modify_expr): For COND_EXPR on LHS, if RHS has void
	type issue error and return early.

	* g++.dg/parse/cond3.C: New test.

From-SVN: r123456

gcc/cp/ChangeLog

+2007-04-03  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/30847
+	* typeck.c (build_modify_expr): For COND_EXPR on LHS, if RHS has void
+	type issue error and return early.
+
 2007-03-30  Jason Merrill  <jason@redhat.com>
 
 	PR c++/31187

gcc/cp/typeck.c

@@ -5702,6 +5702,12 @@ build_modify_expr (tree lhs, enum tree_code modifycode, tree rhs)
 	tree cond;
 	tree preeval = NULL_TREE;
 
+	if (VOID_TYPE_P (TREE_TYPE (rhs)))
+	  {
+	    error ("void value not ignored as it ought to be");
+	    return error_mark_node;
+	  }
+
 	rhs = stabilize_expr (rhs, &preeval);
 
 	/* Check this here to avoid odd errors when trying to convert

gcc/testsuite/ChangeLog

 2007-04-03  Jakub Jelinek  <jakub@redhat.com>
 
+	PR c++/30847
+	* g++.dg/parse/cond3.C: New test.
+
 	PR middle-end/30704
 	* gcc.c-torture/execute/ieee/pr30704.c: New test.
 

gcc/testsuite/g++.dg/parse/cond3.C

+// PR c++/30847
+// { dg-do compile }
+// { dg-options "" }
+
+int j, k, l;
+extern void baz ();
+
+void
+foo (int i)
+{
+  (i ? j : k) = ({ l++; (void) l; });	// { dg-error "void value not ignored" }
+  (i ? j : k) += ({ l++; (void) l; });	// { dg-error "void value not ignored" }
+  (i ? j : k) = baz ();			// { dg-error "void value not ignored" }
+  (i ? j : k) *= baz ();		// { dg-error "void value not ignored" }
+}