X-Recipient: archive-cygwin AT delorie DOT com X-SWARE-Spam-Status: No, hits=-2.6 required=5.0 tests=AWL,BAYES_00,RCVD_IN_DNSWL_NONE,RP_MATCHES_RCVD,TW_YG,UNPARSEABLE_RELAY X-Spam-Check-By: sourceware.org Message-ID: <4F049AE6.4000508@t-online.de> Date: Wed, 04 Jan 2012 19:31:02 +0100 From: Christian Franke User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:7.0.1) Gecko/20110928 Firefox/7.0.1 SeaMonkey/2.4.1 MIME-Version: 1.0 To: cygwin AT cygwin DOT com Subject: mingw64-i686-gcc-4.5.3-4: -Wformat warnings broken in C++ Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-IsSubscribed: yes Mailing-List: contact cygwin-help AT cygwin DOT com; run by ezmlm List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: cygwin-owner AT cygwin DOT com Mail-Followup-To: cygwin AT cygwin DOT com Delivered-To: mailing list cygwin AT cygwin DOT com When printf/scanf functions from MinGW runtime are selected via __USE_MINGW_ANSI_STDIO, then format string checking is broken. This only affects the C++ compiler: $ cygcheck -f /usr/bin/i686-w64-mingw32-g++ mingw64-i686-gcc-g++-4.5.3-4 $ cat testfmt.c #define __USE_MINGW_ANSI_STDIO 1 #include void myprintf(const char *, ...) __attribute__((format(gnu_printf,1,2))); int main() { long long x = 42; printf("%lld\n", x); // C++: Bogus warning myprintf("%lld\n", x); // No warning (OK) printf("%I64d\n", x); // Warning (OK) return 0; } $ i686-w64-mingw32-gcc -Wformat -c testfmt.c testfmt.c: In function 'main': testfmt.c:12:3: warning: format '%I64d' expects type 'int', but argument 2 has type 'long long int' $ i686-w64-mingw32-g++ -Wformat -c testfmt.c testfmt.c: In function 'int main()': testfmt.c:10:21: warning: unknown conversion type character 'l' in format testfmt.c:10:21: warning: too many arguments for format testfmt.c:12:22: warning: format '%I64d' expects type 'int', but argument 2 has type 'long long int' Interestingly the bogus warning only occurs for standard functions like printf(). These are replaced by inline functions in MinGW stdio.h if __USE_MINGW_ANSI_STDIO is set. Probably a subtle bug in the handling of functions known by the compiler. Another observation: Include files from C++ standard library (e.g. ) now silently set __USE_MINGW_ANSI_STDIO: /usr/lib/gcc/i686-w64-mingw32/4.5.3/include/c++/i686-w64-mingw32/bits/os_defines.h: ... #undef __USE_MINGW_ANSI_STDIO #define __USE_MINGW_ANSI_STDIO 1 Both are new issues not seen in previous releases. If desired, I could resend this report to mingw-w64 list. Christian -- Problem reports: http://cygwin.com/problems.html FAQ: http://cygwin.com/faq/ Documentation: http://cygwin.com/docs.html Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple