Module Name: src
Committed By: rillig
Date: Mon Aug 23 06:10:27 UTC 2021
Modified Files:
src/tests/usr.bin/xlint/lint1: msg_141.c msg_141.exp
src/usr.bin/xlint/lint1: tree.c
Log Message:
lint: fix wrong warning about signed integer overflow in '-'
The newly added test cases in line 30 and 33 may or may not be worth a
warning since the expressions deal with unsigned integers, where the
behavior on overflow is well defined.
To generate a diff of this commit:
cvs rdiff -u -r1.3 -r1.4 src/tests/usr.bin/xlint/lint1/msg_141.c \
src/tests/usr.bin/xlint/lint1/msg_141.exp
cvs rdiff -u -r1.346 -r1.347 src/usr.bin/xlint/lint1/tree.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/tests/usr.bin/xlint/lint1/msg_141.c
diff -u src/tests/usr.bin/xlint/lint1/msg_141.c:1.3 src/tests/usr.bin/xlint/lint1/msg_141.c:1.4
--- src/tests/usr.bin/xlint/lint1/msg_141.c:1.3 Mon Aug 23 05:52:04 2021
+++ src/tests/usr.bin/xlint/lint1/msg_141.c Mon Aug 23 06:10:27 2021
@@ -1,16 +1,20 @@
-/* $NetBSD: msg_141.c,v 1.3 2021/08/23 05:52:04 rillig Exp $ */
+/* $NetBSD: msg_141.c,v 1.4 2021/08/23 06:10:27 rillig Exp $ */
# 3 "msg_141.c"
// Test for message: integer overflow detected, op %s [141]
/* lint1-extra-flags: -h */
-/* FIXME */
-/* expect+1: warning: integer overflow detected, op - [141] */
+/*
+ * Before tree.c 1.347 from 2021-08-23, lint wrongly warned about integer
+ * overflow in '-'.
+ */
int signed_int_max = (1u << 31) - 1;
-/* FIXME */
-/* expect+1: warning: integer overflow detected, op - [141] */
+/*
+ * Before tree.c 1.347 from 2021-08-23, lint wrongly warned about integer
+ * overflow in '-'.
+ */
unsigned int unsigned_int_max = (1u << 31) - 1;
/* expect+1: warning: integer overflow detected, op + [141] */
@@ -21,3 +25,9 @@ int int_overflow = (1 << 30) + (1 << 30)
unsigned int intermediate_overflow = (1 << 30) + (1 << 30);
unsigned int no_overflow = (1U << 30) + (1 << 30);
+
+/* expect+1: warning: integer overflow detected, op - [141] */
+unsigned int unsigned_int_min = 0u - (1u << 31);
+
+/* expect+1: warning: integer overflow detected, op - [141] */
+unsigned int unsigned_int_min_unary = -(1u << 31);
Index: src/tests/usr.bin/xlint/lint1/msg_141.exp
diff -u src/tests/usr.bin/xlint/lint1/msg_141.exp:1.3 src/tests/usr.bin/xlint/lint1/msg_141.exp:1.4
--- src/tests/usr.bin/xlint/lint1/msg_141.exp:1.3 Mon Aug 23 05:52:04 2021
+++ src/tests/usr.bin/xlint/lint1/msg_141.exp Mon Aug 23 06:10:27 2021
@@ -1,5 +1,5 @@
-msg_141.c(10): warning: integer overflow detected, op - [141]
-msg_141.c(14): warning: integer overflow detected, op - [141]
-msg_141.c(17): warning: integer overflow detected, op + [141]
msg_141.c(21): warning: integer overflow detected, op + [141]
-msg_141.c(21): warning: initialization of unsigned with negative constant [221]
+msg_141.c(25): warning: integer overflow detected, op + [141]
+msg_141.c(25): warning: initialization of unsigned with negative constant [221]
+msg_141.c(30): warning: integer overflow detected, op - [141]
+msg_141.c(33): warning: integer overflow detected, op - [141]
Index: src/usr.bin/xlint/lint1/tree.c
diff -u src/usr.bin/xlint/lint1/tree.c:1.346 src/usr.bin/xlint/lint1/tree.c:1.347
--- src/usr.bin/xlint/lint1/tree.c:1.346 Sun Aug 22 21:27:15 2021
+++ src/usr.bin/xlint/lint1/tree.c Mon Aug 23 06:10:26 2021
@@ -1,4 +1,4 @@
-/* $NetBSD: tree.c,v 1.346 2021/08/22 21:27:15 rillig Exp $ */
+/* $NetBSD: tree.c,v 1.347 2021/08/23 06:10:26 rillig Exp $ */
/*
* Copyright (c) 1994, 1995 Jochen Pohl
@@ -37,7 +37,7 @@
#include <sys/cdefs.h>
#if defined(__RCSID) && !defined(lint)
-__RCSID("$NetBSD: tree.c,v 1.346 2021/08/22 21:27:15 rillig Exp $");
+__RCSID("$NetBSD: tree.c,v 1.347 2021/08/23 06:10:26 rillig Exp $");
#endif
#include <float.h>
@@ -3094,13 +3094,11 @@ fold(tnode_t *tn)
break;
case MINUS:
q = utyp ? (int64_t)(ul - ur) : sl - sr;
- if (msb(sl, t, -1) && !msb(sr, t, -1)) {
- if (!msb(q, t, -1))
- ovfl = true;
- } else if (!msb(sl, t, -1) && msb(sr, t, -1)) {
- if (msb(q, t, -1))
- ovfl = true;
- }
+ if (!utyp &&
+ msb(sl, t, -1) && !msb(sr, t, -1) && !msb(q, t, -1))
+ ovfl = true;
+ if (!msb(sl, t, -1) && msb(sr, t, -1) && msb(q, t, -1))
+ ovfl = true;
break;
case SHL:
q = utyp ? (int64_t)(ul << sr) : sl << sr;
