 @@ -1,14 +1,14 @@
-/*	$NetBSD: tree.c,v 1.129 2021/01/04 22:41:56 rillig Exp $	*/
+/*	$NetBSD: tree.c,v 1.130 2021/01/04 23:17:03 rillig Exp $	*/
 /*
  * Copyright (c) 1994, 1995 Jochen Pohl
  * All Rights Reserved.
+ *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
 @@ -27,27 +27,27 @@
  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 #if HAVE_NBTOOL_CONFIG_H
 #include "nbtool_config.h"
 #endif
 #include <sys/cdefs.h>
 #if defined(__RCSID) && !defined(lint)
-__RCSID("$NetBSD: tree.c,v 1.129 2021/01/04 22:41:56 rillig Exp $");
+__RCSID("$NetBSD: tree.c,v 1.130 2021/01/04 23:17:03 rillig Exp $");
 #endif
 #include <float.h>
 #include <limits.h>
 #include <math.h>
 #include <signal.h>
 #include <stdlib.h>
 #include <string.h>
 #include "lint1.h"
 #include "cgram.h"
 static	tnode_t	*new_integer_constant_node(tspec_t, int64_t);
 @@ -4007,38 +4007,42 @@ check_precedence_confusion(tnode_t *tn)
 	dprint_node(tn);
 	if (mp->m_binary) {
 		rparn = 0;
 		/*
 		 * FIXME: There is a typo "tn->tn_op == CVT", which should
 		 * rather be "rn->tn_op".  Since tn must be a binary operator,
 		 * it can never be CVT.
+		 *
 		 * Before fixing this though, there should be a unit test
 		 * that demonstrates an actual change in behavior when this
 		 * bug gets fixed.
+		 *
-		 * Right now, the condition is always false.  To make it true
+		 * rn must be a chain of casts and conversions, and at least
-		 * after fixing the typo, the right-hand operand must be an
+		 * one of these must be a parenthesized cast.
 		 * explicit cast or an implicit conversion that is
 		 * parenthesized.  For the right-hand operand itself, this
 		 * would already be done using the line below the loop.
+		 *
-		 * To make a difference, the right-hand operand must not be
+		 * The argument of the innermost cast or conversion must not
-		 * parenthesized, but its indirect cast or conversion must be.
+		 * be parenthesized.
+		 *
-		 * An implicit conversion is never parenthesized.  Therefore
+		 * The argument of the innermost cast or conversion must be
-		 * this must be a cast that is later converted, to build a
+		 * an expression with confusing precedence.  Since all these
-		 * chain.
+		 * expressions have lower precedence than a cast, these can
 		 * only appear as a parenthesized expression.  This in turn
 		 * makes the whole loop superfluous.
+		 *
 		 * An edge case might be due to constant folding, if the
 		 * nodes created from constant folding did not preserve
 		 * tn_parenthesized properly.  But that would be another bug,
 		 * so it doesn't count as an argument.
 		 */
 		for (rn = tn->tn_right; tn->tn_op == CVT; rn = rn->tn_left)
 			rparn |= rn->tn_parenthesized;
 		rparn |= rn->tn_parenthesized;
 		rop = rn->tn_op;
+	}
 	dowarn = 0;
 	switch (tn->tn_op) {
 	case SHL:
 	case SHR:
 		if (!lparn && (lop == PLUS || lop == MINUS)) {