From patchwork Tue Sep 3 10:12:54 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Florian Weimer X-Patchwork-Id: 34375 Received: (qmail 91707 invoked by alias); 3 Sep 2019 10:13:04 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Delivered-To: mailing list libc-alpha@sourceware.org Received: (qmail 91668 invoked by uid 89); 3 Sep 2019 10:13:03 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-18.5 required=5.0 tests=AWL, BAYES_00, GIT_PATCH_0, GIT_PATCH_1, GIT_PATCH_2, GIT_PATCH_3, SPF_HELO_PASS autolearn=ham version=3.3.1 spammy=strange, H*i:sk:4679ba6, H*f:sk:4679ba6 X-HELO: mx1.redhat.com From: Florian Weimer To: Szabolcs Nagy Cc: nd , Carlos O'Donell , Martin Sebor , Steve Ellcey , "libc-alpha\@sourceware.org" , "msebor\@redhat.com" Subject: Re: ToT glibc build problem with ToT GCC References: <486309d08583ed1c27a001d946205850b421f7ad.camel@marvell.com> <53b36206-3f07-432b-9d0f-02520debe4b8@gmail.com> <2e5c0137-4109-e7ce-8d1d-9c268e086f81@gmail.com> <87ef126bvu.fsf@oldenburg2.str.redhat.com> <87mufq4og4.fsf@oldenburg2.str.redhat.com> <4679ba62-85c2-cc52-1a9d-5c75b3005344@arm.com> Date: Tue, 03 Sep 2019 12:12:54 +0200 In-Reply-To: <4679ba62-85c2-cc52-1a9d-5c75b3005344@arm.com> (Szabolcs Nagy's message of "Tue, 3 Sep 2019 09:51:55 +0000") Message-ID: <87lfv5sn6h.fsf@oldenburg2.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.2 (gnu/linux) MIME-Version: 1.0 * Szabolcs Nagy: > On 30/08/2019 17:18, Florian Weimer wrote: >> >> localedef: Use initializer for flexible array member [BZ #24950] >> > > i would mention that you put the struct in .rodata, > that is a non-obvious change. Please see below. > i'm fine with using gcc extension for the initializer. > i think the union solution is a bit safer though. > either way, it would be nice to fix this build error. I don't think this is a GCC extension. I believe it's part of C99. Thanks, Florian localedef: Use initializer for flexible array member [BZ #24950] struct charseq used a zero-length array instead of a flexible array member. This required a strange construct to initialize struct charseq objects, and GCC 10 warns about that: cc1: error: writing 1 byte into a region of size 0 [-Werror=stringop-overflow=] In file included from programs/repertoire.h:24, from programs/localedef.h:32, from programs/ld-ctype.c:35: programs/charmap.h:63:17: note: destination object declared here 63 | unsigned char bytes[0]; | ^~~~~ cc1: error: writing 1 byte into a region of size 0 [-Werror=stringop-overflow=] programs/charmap.h:63:17: note: destination object declared here cc1: error: writing 1 byte into a region of size 0 [-Werror=stringop-overflow=] programs/charmap.h:63:17: note: destination object declared here cc1: error: writing 1 byte into a region of size 0 [-Werror=stringop-overflow=] programs/charmap.h:63:17: note: destination object declared here The change makes the object physically const, but it is not expected to be modified. 2019-08-30 Florian Weimer [BZ #24950] * locale/programs/charmap.h (struct charseq): Turn bytes into a flexible array member. * locale/programs/ld-ctype.c (ctype_finish): Use initializer for replace. diff --git a/locale/programs/charmap.h b/locale/programs/charmap.h index 870a9e9577..70db330d29 100644 --- a/locale/programs/charmap.h +++ b/locale/programs/charmap.h @@ -60,7 +60,7 @@ struct charseq const char *name; uint32_t ucs4; int nbytes; - unsigned char bytes[0]; + unsigned char bytes[]; }; diff --git a/locale/programs/ld-ctype.c b/locale/programs/ld-ctype.c index cfc9c43fd5..9123f64a56 100644 --- a/locale/programs/ld-ctype.c +++ b/locale/programs/ld-ctype.c @@ -842,8 +842,6 @@ no input digits defined and none of the standard names in the charmap")); for (cnt = 0; cnt < 10; ++cnt) if (ctype->mboutdigits[cnt] == NULL) { - static struct charseq replace[2]; - if (!warned) { record_error (0, 0, _("\ @@ -851,10 +849,12 @@ not all characters used in `outdigit' are available in the charmap")); warned = 1; } - replace[0].nbytes = 1; - replace[0].bytes[0] = '?'; - replace[0].bytes[1] = '\0'; - ctype->mboutdigits[cnt] = &replace[0]; + static const struct charseq replace = + { + .nbytes = 1, + .bytes = "?", + }; + ctype->mboutdigits[cnt] = (struct charseq *) &replace; } warned = 0;