From 4329029317e4cba70f0582b5f8a1a69a6f6afae8 Mon Sep 17 00:00:00 2001
From: rillig <rillig@NetBSD.org>
Date: Tue, 6 Apr 2021 21:17:27 +0000
Subject: [PATCH] lint: fix wrong warning about losing accuracy when converting
 to _Bool

---
 tests/usr.bin/xlint/lint1/msg_132.c   | 9 +++++++--
 tests/usr.bin/xlint/lint1/msg_132.exp | 1 -
 usr.bin/xlint/lint1/tree.c            | 7 +++++--
 3 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/tests/usr.bin/xlint/lint1/msg_132.c b/tests/usr.bin/xlint/lint1/msg_132.c
index 39b172ef518d..40db193e9d52 100644
--- a/tests/usr.bin/xlint/lint1/msg_132.c
+++ b/tests/usr.bin/xlint/lint1/msg_132.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: msg_132.c,v 1.4 2021/04/06 21:10:37 rillig Exp $	*/
+/*	$NetBSD: msg_132.c,v 1.5 2021/04/06 21:17:28 rillig Exp $	*/
 # 3 "msg_132.c"
 
 // Test for message: conversion from '%s' to '%s' may lose accuracy [132]
@@ -63,9 +63,14 @@ convert_signed(i8 v8, i16 v16, i32 v32, i64 v64)
 	v64 = v32;
 }
 
+/*
+ * Before tree.c 1.268 from 2021-04-06, lint wrongly warned that conversion to
+ * _Bool might lose accuracy.  C99 6.3.1.2 defines a special conversion rule
+ * from scalar to _Bool though.
+ */
 _Bool
 to_bool(long a, long b)
 {
 	/* seen in fp_lib.h, function wideRightShiftWithSticky */
-	return a | b;		/* expect: 132 *//*FIXME*/
+	return a | b;
 }
diff --git a/tests/usr.bin/xlint/lint1/msg_132.exp b/tests/usr.bin/xlint/lint1/msg_132.exp
index 3c208a518cdd..c96ff05221e6 100644
--- a/tests/usr.bin/xlint/lint1/msg_132.exp
+++ b/tests/usr.bin/xlint/lint1/msg_132.exp
@@ -10,4 +10,3 @@ msg_132.c(51): warning: conversion from 'long long' to 'signed char' may lose ac
 msg_132.c(54): warning: conversion from 'int' to 'short' may lose accuracy [132]
 msg_132.c(55): warning: conversion from 'long long' to 'short' may lose accuracy [132]
 msg_132.c(59): warning: conversion from 'long long' to 'int' may lose accuracy [132]
-msg_132.c(70): warning: conversion from 'long' to '_Bool' may lose accuracy [132]
diff --git a/usr.bin/xlint/lint1/tree.c b/usr.bin/xlint/lint1/tree.c
index 3ca1557de5cc..e10e36922f2b 100644
--- a/usr.bin/xlint/lint1/tree.c
+++ b/usr.bin/xlint/lint1/tree.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: tree.c,v 1.267 2021/04/06 13:17:04 rillig Exp $	*/
+/*	$NetBSD: tree.c,v 1.268 2021/04/06 21:17:27 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 1.267 2021/04/06 13:17:04 rillig Exp $");
+__RCSID("$NetBSD: tree.c,v 1.268 2021/04/06 21:17:27 rillig Exp $");
 #endif
 
 #include <float.h>
@@ -1948,6 +1948,9 @@ check_integer_conversion(op_t op, int arg, tspec_t nt, tspec_t ot, type_t *tp,
 	if (op == CVT)
 		return;
 
+	if (Sflag && nt == BOOL)
+		return;		/* See C99 6.3.1.2 */
+
 	if (Pflag && portable_size_in_bits(nt) > portable_size_in_bits(ot) &&
 	    is_uinteger(nt) != is_uinteger(ot)) {
 		if (aflag > 0 && pflag) {