From mboxrd@z Thu Jan 1 00:00:00 1970 From: John Spencer Subject: Re: [PATCH 2/2] perf Makefile: default WERROR to off. Date: Tue, 26 Aug 2014 14:11:51 +0200 Message-ID: <53FC7987.10509@barfooze.de> References: <53FB9064.1050000@barfooze.de> <87oav7bv25.fsf@sejong.aot.lge.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from hindenburg.barfooze.de ([195.154.9.123]:39502 "EHLO hindenburg.barfooze.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932808AbaHZMOE (ORCPT ); Tue, 26 Aug 2014 08:14:04 -0400 In-Reply-To: <87oav7bv25.fsf@sejong.aot.lge.com> Sender: linux-perf-users-owner@vger.kernel.org List-ID: To: Namhyung Kim Cc: linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org Namhyung Kim wrote: > On Mon, 25 Aug 2014 21:37:08 +0200, John Spencer wrote: >> From 4a72032828a6784d93f4becf723303a17d723544 Mon Sep 17 00:00:00 2001 >> From: John Spencer >> Date: Mon, 25 Aug 2014 21:25:43 +0200 >> Subject: [PATCH 2/2] perf Makefile: default WERROR to off. >> >> Having WERROR on by default breaks build everywhere the author hasn't >> tested so far; including musl libc which warns about wrong includes. >> >> The unsuspecting user will think there's something broken and only >> if he's coureageuous enough to grep the Makefile infrastructure find >> out that he may be able to get the build working with WERROR=0. >> >> OTOH with WERROR defaulting to off, anything will work for the user >> and the maintainer can knowingly use WERROR=1 to do his test builds. > > I think it's intentionally turned on to fix any warnings in the first > place. But yes, it might miss some non-popular systems tho.. yes, and it's sufficient if someone tries to build it with a newer/different compiler/libc version/whatever to make it fail. having -Werror on by default is just silly and annoying because 90% of warnings (at least with -Wall) are utterly unimportant (like unused variables etc). there's probably a good reason the kernel itself is not built with -Werror. (in my head i call people hardcoding -Werror "Werror-nazis"...) but i agree that *some* warnings should be fatal, for example implicit function declarations, or pointer-to-int casts, because those can actually break code. > > How many errors/warnings do you see on your system (musl libc?). Any > chance to post fixes instead? there are tons of warnings, mostly from mixing kernel headers with userspace headers (and libc_compat.h is only patched for GLIBC - my musl-related libc_compat.h patches have been ignored so far, but they're archived at https://github.com/sabotage-linux/kernel-headers ). In file included from perf.c:12:0: util/cache.h:74:15: warning: redundant redeclaration of 'strlcpy' [-Wredundant-decls] In file included from util/util.h:53:0, from builtin.h:4, from perf.c:9: /usr/include/string.h:84:8: note: previous declaration of 'strlcpy' was here In file included from util/util.h:67:0, from builtin.h:4, from perf.c:9: /usr/include/sys/poll.h:1:2: warning: #warning redirecting incorrect #include to [-Wcpp] In file included from /src/build/kernel/linux-3.14.14.org/arch/x86/include/uapi/asm/ioctl.h:1:0, from /src/build/kernel/linux-3.14.14.org/include/uapi/linux/ioctl.h:4, from /src/build/kernel/linux-3.14.14.org/include/uapi/linux/perf_event.h:18, from util/../perf.h:156, from util/cache.h:7, from perf.c:12: /src/build/kernel/linux-3.14.14.org/include/uapi/asm-generic/ioctl.h:65:0: warning: "_IOC" redefined [enabled by default] In file included from /usr/include/sys/ioctl.h:7:0, from util/util.h:69, from builtin.h:4, from perf.c:9: /usr/include/bits/ioctl.h:1:0: note: this is the location of the previous definition In file included from /src/build/kernel/linux-3.14.14.org/arch/x86/include/uapi/asm/ioctl.h:1:0, from /src/build/kernel/linux-3.14.14.org/include/uapi/linux/ioctl.h:4, from /src/build/kernel/linux-3.14.14.org/include/uapi/linux/perf_event.h:18, from util/../perf.h:156, from util/cache.h:7, from perf.c:12: /src/build/kernel/linux-3.14.14.org/include/uapi/asm-generic/ioctl.h:76:0: warning: "_IO" redefined [enabled by default] (same for _IOR, _IOW, _IOWR, _IOC) these warnings are repeated over an over again as they come from headers. so basically we have - util/cache.h:74:15: warning: redundant redeclaration of 'strlcpy' - uapi/asm-generic/ioctl.h: warning: "_IO*" redefined (userspace and kernel space defining the same thing) - util/util.h: incorrect inclusion of sys/poll.h rather than poll.h (see man 3p poll) tho it's possible I may have missed something else in the wall of warnings. Thanks, --JS > > Thanks, > Namhyung > > >> Signed-off-by: John Spencer >> >> --- >> tools/perf/config/Makefile | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/tools/perf/config/Makefile b/tools/perf/config/Makefile >> index 1f67aa0..b1d639a 100644 >> --- a/tools/perf/config/Makefile >> +++ b/tools/perf/config/Makefile >> @@ -102,7 +102,7 @@ ifeq ($(call get-executable,$(BISON)),) >> endif >> >> # Treat warnings as errors unless directed not to >> -ifneq ($(WERROR),0) >> +ifeq ($(WERROR),1) >> CFLAGS += -Werror >> endif >