forked from brl/citadel
91 lines
3.2 KiB
Diff
91 lines
3.2 KiB
Diff
From 037283cbc74739b72f36dfec827d120faa243406 Mon Sep 17 00:00:00 2001
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From: Florian Weimer <fweimer at redhat dot com>
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Date: Thu, 6 Jul 2017 11:50:55 +0200
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Subject: [PATCH 26/26] assert: Suppress pedantic warning caused by statement
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expression [BZ# 21242]
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On 07/05/2017 10:15 PM, Zack Weinberg wrote:
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> On Wed, Jul 5, 2017 at 11:51 AM, Florian Weimer <fweimer@redhat.com> wrote:
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>> On 07/05/2017 05:46 PM, Zack Weinberg wrote:
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>>> A problem occurs to me: expressions involving VLAs _are_ evaluated
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>>> inside sizeof.
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>>
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>> The type of the sizeof argument would still be int (due to the
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>> comparison against 0), so this doesn't actually occur.
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>
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> I rechecked what C99 says about sizeof and VLAs, and you're right -
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> the operand of sizeof is only evaluated when sizeof is _directly_
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> applied to a VLA. So this is indeed safe, but I think this wrinkle
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> should be mentioned in the comment. Perhaps
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>
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> /* The first occurrence of EXPR is not evaluated due to the sizeof,
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> but will trigger any pedantic warnings masked by the __extension__
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> for the second occurrence. The explicit comparison against zero
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> ensures that sizeof is not directly applied to a function pointer or
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> bit-field (which would be ill-formed) or VLA (which would be evaluated). */
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>
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> zw
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What about the attached patch?
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Siddhesh, is this okay during the freeze? I'd like to backport it to
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2.25 as well.
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Thanks,
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Florian
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assert: Suppress pedantic warning caused by statement expression
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2017-07-06 Florian Weimer <fweimer@redhat.com>
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[BZ #21242]
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* assert/assert.h [__GNUC__ && !__STRICT_ANSI__] (assert):
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Suppress pedantic warning resulting from statement expression.
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(__ASSERT_FUNCTION): Add missing __extendsion__.
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---
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Upstream-Status: Submitted
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Signed-off-by: Khem Raj <raj.khem@gmail.com>
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assert/assert.h | 12 +++++++++---
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1 file changed, 9 insertions(+), 3 deletions(-)
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diff --git a/assert/assert.h b/assert/assert.h
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index 22f019537c..6801cfeb10 100644
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--- a/assert/assert.h
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+++ b/assert/assert.h
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@@ -91,13 +91,19 @@ __END_DECLS
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? __ASSERT_VOID_CAST (0) \
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: __assert_fail (#expr, __FILE__, __LINE__, __ASSERT_FUNCTION))
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# else
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+/* The first occurrence of EXPR is not evaluated due to the sizeof,
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+ but will trigger any pedantic warnings masked by the __extension__
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+ for the second occurrence. The explicit comparison against zero is
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+ required to support function pointers and bit fields in this
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+ context, and to suppress the evaluation of variable length
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+ arrays. */
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# define assert(expr) \
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- ({ \
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+ ((void) sizeof ((expr) == 0), __extension__ ({ \
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if (expr) \
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; /* empty */ \
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else \
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__assert_fail (#expr, __FILE__, __LINE__, __ASSERT_FUNCTION); \
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- })
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+ }))
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# endif
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# ifdef __USE_GNU
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@@ -113,7 +119,7 @@ __END_DECLS
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C9x has a similar variable called __func__, but prefer the GCC one since
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it demangles C++ function names. */
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# if defined __cplusplus ? __GNUC_PREREQ (2, 6) : __GNUC_PREREQ (2, 4)
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-# define __ASSERT_FUNCTION __PRETTY_FUNCTION__
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+# define __ASSERT_FUNCTION __extension__ __PRETTY_FUNCTION__
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# else
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# if defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901L
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# define __ASSERT_FUNCTION __func__
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--
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2.13.3
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