re PR c++/35987 (ICE with invalid if-condition)

	PR c++/35987
	* typeck.c (cp_build_modify_expr) <case PREINCREMENT_EXPR>: Don't build
	COMPOUND_EXPR if the second argument would be error_mark_node.

	* g++.dg/other/error28.C: New test.

From-SVN: r134786

gcc/cp/ChangeLog

+2008-04-29  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/35987
+	* typeck.c (cp_build_modify_expr) <case PREINCREMENT_EXPR>: Don't build
+	COMPOUND_EXPR if the second argument would be error_mark_node.
+
 2008-04-28  Jason Merrill  <jason@redhat.com>
 	    Liu Guanwei <liu_gw@163.com>
 

gcc/cp/typeck.c

@@ -5945,10 +5945,11 @@ cp_build_modify_expr (tree lhs, enum tree_code modifycode, tree rhs,
 	lhs = build2 (TREE_CODE (lhs), TREE_TYPE (lhs),
 		      stabilize_reference (TREE_OPERAND (lhs, 0)),
 		      TREE_OPERAND (lhs, 1));
-      return build2 (COMPOUND_EXPR, lhstype,
-		     lhs,
-		     cp_build_modify_expr (TREE_OPERAND (lhs, 0),
-					   modifycode, rhs, complain));
+      newrhs = cp_build_modify_expr (TREE_OPERAND (lhs, 0),
+				     modifycode, rhs, complain);
+      if (newrhs == error_mark_node)
+	return error_mark_node;
+      return build2 (COMPOUND_EXPR, lhstype, lhs, newrhs);
 
       /* Handle (a, b) used as an "lvalue".  */
     case COMPOUND_EXPR:

gcc/testsuite/ChangeLog

+2008-04-29  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/35987
+	* g++.dg/other/error28.C: New test.
+
 2008-04-28  Uros Bizjak  <ubizjak@gmail.com>
 
 	PR target/36073

gcc/testsuite/g++.dg/other/error28.C

+// PR c++/35987
+// { dg-do compile }
+
+void
+foo (char *p)
+{
+  if (++p = true);	// { dg-error "cannot convert" }
+}