From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [63.128.21.124]) by sourceware.org (Postfix) with ESMTP id 95DD63875449 for ; Mon, 4 Jan 2021 16:58:05 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 95DD63875449 Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-208-Sly3B73VOMedrozLL0NwPA-1; Mon, 04 Jan 2021 11:58:03 -0500 X-MC-Unique: Sly3B73VOMedrozLL0NwPA-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 2D387803628; Mon, 4 Jan 2021 16:58:02 +0000 (UTC) Received: from oldenburg2.str.redhat.com (ovpn-112-120.ams2.redhat.com [10.36.112.120]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 4C0D560BE5; Mon, 4 Jan 2021 16:58:01 +0000 (UTC) From: Florian Weimer To: Martin Sebor Cc: Martin Sebor via Libc-alpha , Joseph Myers Subject: Re: [PATCH] add support for -Wmismatched-dealloc References: <74efece7-9a4b-83ee-7fdd-475c0d514378@gmail.com> <758e723b-67cf-a211-7bc2-2ccd3fc744e5@gmail.com> <2555516b-4583-21fc-e844-fd44619488cd@gmail.com> <655918b2-16c6-74b1-6a49-505a7607007f@gmail.com> <87mtxok7ob.fsf@oldenburg2.str.redhat.com> <0aae9006-6001-8fc8-ad6d-c8e3ee60f82c@gmail.com> Date: Mon, 04 Jan 2021 17:57:59 +0100 In-Reply-To: <0aae9006-6001-8fc8-ad6d-c8e3ee60f82c@gmail.com> (Martin Sebor's message of "Mon, 4 Jan 2021 09:18:12 -0700") Message-ID: <87turwiqqw.fsf@oldenburg2.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain X-Spam-Status: No, score=-12.5 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, RCVD_IN_DNSWL_LOW, RCVD_IN_MSPIKE_H4, RCVD_IN_MSPIKE_WL, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 04 Jan 2021 16:58:07 -0000 * Martin Sebor: > On 1/4/21 9:07 AM, Florian Weimer wrote: >> * Martin Sebor via Libc-alpha: >> >>> diff --git a/wcsmbs/wchar.h b/wcsmbs/wchar.h >>> index 9cf8b05a87..4c1c7f1119 100644 >>> --- a/wcsmbs/wchar.h >>> +++ b/wcsmbs/wchar.h >>> @@ -151,7 +151,8 @@ extern size_t wcsxfrm_l (wchar_t *__s1, const wchar_t *__s2, >>> size_t __n, locale_t __loc) __THROW; >>> /* Duplicate S, returning an identical malloc'd string. */ >>> -extern wchar_t *wcsdup (const wchar_t *__s) __THROW __attribute_malloc__; >>> +extern wchar_t *wcsdup (const wchar_t *__s) __THROW >>> + __attribute_malloc__ __attr_dealloc_free; >>> #endif >>> /* Find the first occurrence of WC in WCS. */ >>> @@ -562,9 +563,18 @@ extern wchar_t *wcpncpy (wchar_t *__restrict __dest, >>> /* Wide character I/O functions. */ >>> #if defined __USE_XOPEN2K8 || __GLIBC_USE (LIB_EXT2) >>> +# ifdef __REDIRECT >>> +/* Declare the __fclose alias and associate it as a deallocator >>> + with open_wmemstream below. */ >>> +extern int __REDIRECT (__fclose, (FILE *), fclose); >>> +# define __attr_dealloc_fclose __attr_dealloc (__fclose, 1) >>> +# else >>> +# define __attr_dealloc_fclose /* empty */ >>> +# endif >>> /* Like OPEN_MEMSTREAM, but the stream is wide oriented and produces >>> a wide character string. */ >>> -extern __FILE *open_wmemstream (wchar_t **__bufloc, size_t *__sizeloc) __THROW; >>> +extern __FILE *open_wmemstream (wchar_t **__bufloc, size_t *__sizeloc) __THROW >>> + __attribute_malloc__ __attr_dealloc_fclose; >>> #endif >>> #if defined __USE_ISOC95 || defined __USE_UNIX98 >> Why is an alias for fclose needed here, but not for free? > > Because fclose is not a built-in so there's no __builtin_fclose > to associate open_wmemstream with. free is a built-in and so > __attr_dealloc_free just references __builtin_free and doesn't > need an explicit declaration. Ahh, that explains the discrepancy. I'm a bit worried that the __fclose alias causes problems. Would it be possible to add __builtin_fclose to GCC instead? Based on how this patch appears to make both __fclose and fclose acceptable as a deallocator, GCC resolves redirects as part of the matching check. I wonder if this constrains the usefulness of the attribute in some way. I can imagine situations where at the source level, different deallocators should be used (say to support debugging builds), but release builds redirect different deallocators to the same implementation. Thanks, Florian -- Red Hat GmbH, https://de.redhat.com/ , Registered seat: Grasbrunn, Commercial register: Amtsgericht Muenchen, HRB 153243, Managing Directors: Charles Cachera, Brian Klemm, Laurie Krebs, Michael O'Neill