From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on inbox.vuxu.org X-Spam-Level: X-Spam-Status: No, score=-3.1 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.4 Received: from second.openwall.net (second.openwall.net [193.110.157.125]) by inbox.vuxu.org (Postfix) with SMTP id 8C29725475 for ; Mon, 26 Feb 2024 15:36:31 +0100 (CET) Received: (qmail 24504 invoked by uid 550); 26 Feb 2024 14:32:56 -0000 Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Reply-To: musl@lists.openwall.com Received: (qmail 24466 invoked from network); 26 Feb 2024 14:32:56 -0000 Date: Mon, 26 Feb 2024 09:36:34 -0500 From: Rich Felker To: Jens Gustedt Cc: musl@lists.openwall.com, Gabriel Ravier , Jules Maselbas Message-ID: <20240226143634.GH4163@brightrain.aerifal.cx> References: <20240125141440.13906-1-jmaselbas@zdiv.net> <20240226021749.GG4163@brightrain.aerifal.cx> <0a3fb421-dc8f-4cbb-97e3-b11cc7608d24@gmail.com> <6E11337A-7274-40D9-8124-B86EB32B204B@inria.fr> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6E11337A-7274-40D9-8124-B86EB32B204B@inria.fr> User-Agent: Mutt/1.5.21 (2010-09-15) Subject: Re: [musl] [PATCH v2] prevent from redefining __STDC_UTF_{16,32}__ macros On Mon, Feb 26, 2024 at 08:14:52AM +0100, Jens Gustedt wrote: > Hi > > Am 26. Februar 2024 04:47:22 MEZ schrieb Gabriel Ravier : > > On 2/26/24 02:17, Rich Felker wrote: > > > On Thu, Jan 25, 2024 at 03:14:40PM +0100, Jules Maselbas wrote: > > >> Undefine any previous __STDC_UTF_{16,32}__ macros before defining > > >> them to prenvent any warnings of redefining macros. > > >> > > >> --- > > >> v2: > > >> - changed `#if !define(...)` guard to `#undef`, as suggested by Rich Felker > > >> > > >> I encountered this "issue" trying to compile a program with the -isystem > > >> option to override toolchain/installed musl headers with one from source. > > >> > > >> include/stdc-predef.h | 3 +++ > > >> 1 file changed, 3 insertions(+) > > >> > > >> diff --git a/include/stdc-predef.h b/include/stdc-predef.h > > >> index af1a2799..5ccd884d 100644 > > >> --- a/include/stdc-predef.h > > >> +++ b/include/stdc-predef.h > > >> @@ -7,7 +7,10 @@ > > >> #define __STDC_IEC_559__ 1 > > >> #endif > > >> +#undef __STDC_UTF_16__ > > >> #define __STDC_UTF_16__ 1 > > >> + > > >> +#undef __STDC_UTF_32__ > > >> #define __STDC_UTF_32__ 1 > > >> #endif > > >> -- > > >> 2.43.0 > > > I merged this, but now gcc warns about undefining them if system > > > header warnings aren't suppressed. I'm not sure what the justification > > > is for that... *sigh* > > > > > > Rich > > > > It appears as though since 2001 GCC makes it so that any > > redefinition or undefinition of any macro with a name starting > > with "__STDC_" (with hard-coded exceptions for > > __STDC_FORMAT_MACROS, __STDC_LIMIT_MACROS and > > __STDC_CONSTANT_MACROS) always results in a warning (from reading > > the code this doesn't seem to be tied to any -W switch, so it's > > simply entirely impossible to work around) > > > > The way to go would be to #ifdef them, not to use #undef. > These are really a language feature and not library, so anything > that this should do is repair work for older compilers. The > compiler's setting, if any, should prime over the C library. > > With C23 these two macros become mandatory. I think the gcc folks originally saw them as library-dependent, maybe because of the char16_t/char32_t library functions. This is why we had to define them ourselves in the first place. However indeed they are a matter of how the compiler translates literals. I'm okay with just switching to the original patch with #ifndef. But it's probably unfortunate that gcc is this aggressive about the issue. Rich