From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 18335 invoked by alias); 26 Feb 2015 02:38:48 -0000 Mailing-List: contact gdb-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-owner@sourceware.org Received: (qmail 18314 invoked by uid 89); 26 Feb 2015 02:38:46 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=1.5 required=5.0 tests=AWL,BAYES_50,FREEMAIL_FROM,KAM_FROM_URIBL_PCCC,RCVD_IN_DNSWL_LOW,SPF_PASS autolearn=no version=3.3.2 X-HELO: mail-lb0-f181.google.com Received: from mail-lb0-f181.google.com (HELO mail-lb0-f181.google.com) (209.85.217.181) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES128-GCM-SHA256 encrypted) ESMTPS; Thu, 26 Feb 2015 02:38:45 +0000 Received: by lbvn10 with SMTP id n10so8024028lbv.4 for ; Wed, 25 Feb 2015 18:38:42 -0800 (PST) MIME-Version: 1.0 X-Received: by 10.112.173.133 with SMTP id bk5mr5444518lbc.94.1424918322254; Wed, 25 Feb 2015 18:38:42 -0800 (PST) Received: by 10.25.21.213 with HTTP; Wed, 25 Feb 2015 18:38:42 -0800 (PST) In-Reply-To: References: <0AB56024-875B-4724-8ED2-A9DDB237CBFF@dell.com> <23CC7871-C616-436C-920C-4A635DC87189@dell.com> <7A311B56-C424-4C4F-A0E4-B12B65131745@gmail.com> <225BDA7A-3A1F-4F94-8086-E44249E273D5@gmail.com> Date: Thu, 26 Feb 2015 08:46:00 -0000 Message-ID: Subject: Re: format string is not a string literal From: Andrew Pinski To: Simon Marchi Cc: Jack Howarth , "Paul_Koning@dell.com" , "gdb@sourceware.org" Content-Type: text/plain; charset=UTF-8 X-IsSubscribed: yes X-SW-Source: 2015-02/txt/msg00062.txt.bz2 On Wed, Feb 25, 2015 at 6:35 PM, Andrew Pinski wrote: > On Wed, Feb 25, 2015 at 6:30 PM, Simon Marchi wrote: >>>> On Feb 25, 2015, at 4:41 PM, Jack Howarth wrote: >>>> >>>> Andrew, >>>> See the additional comments from the llvm.org clang developers at... >>>> >>>> http://llvm.org/bugs/show_bug.cgi?id=22701#c5 >>> >>> Then put this warning under a different flag. Anyways clang is broken and gdb should not change due to a broken compiler. >>> >>> Thanks, >>> Andrew >> >> I would not say that clang is broken or that the warning is unclear. >> The flag is -Wformat-nonliteral and the warning message is "format >> string is not a string literal". I don't know how you can be more >> clear and direct about the fact that the format string is not a string >> literal. Looking at the code, we observe that clang is right (the >> format string is indeed not a string literal). With the proper >> function attributes, the compiler could do better checks and prevent >> programming mistakes. Since clang pointed out this low-hanging fruit >> improvement to gdb's code, why shouldn't we take advantage of it? >> >> Anyway, Jack, you are welcome to submit a patch for this if you feel >> like it and/or file a bug if it is not already done. > > > Except GCC documents this options differently than clang implements: > -Wformat-nonliteralIf -Wformat is specified, also warn if the format > string is not a string literal and so cannot be checked, unless the > format function takes its format arguments as a va_list. > > > Notice the last part of the documentation. > > So this again is clang implements a GCC option but does not follow the > documentation of GCC. > How does clang document this option? > GCC has always documented this option this way since at least 3.1.1: https://gcc.gnu.org/onlinedocs/gcc-3.1.1/gcc/Warning-Options.html#Warning%20Options And there is no user documentation for clang for this option so clang is broken. Thanks, Andrew > Thanks, > Andrew > >> >> Simon