Date: Thu, 24 May 2018 09:00:19 -0700 From: Matthew Macy <mmacy@freebsd.org> To: Warner Losh <imp@bsdimp.com> Cc: Michael Tuexen <Michael.Tuexen@macmic.franken.de>, Gleb Smirnoff <glebius@freebsd.org>, src-committers <src-committers@freebsd.org>, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r333860 - head/sys/kern Message-ID: <CAPrugNqGhGiSyVTORvy%2Bv0U2rgd1SN-%2BOw0m3USp0hiv5wg7vg@mail.gmail.com> In-Reply-To: <CANCZdfov%2Bb441dN7shE5JY%2BxgKnT41sVfdwrirxUDUOxkSQrJQ@mail.gmail.com> References: <201805190510.w4J5AqfS054367@repo.freebsd.org> <20180523222743.GU71675@FreeBSD.org> <CAPrugNpKxEVx%2Bg0D6qUwq=yw_W-QeuntupwAjteK1yALkJktag@mail.gmail.com> <20180523225729.GV71675@FreeBSD.org> <CAPrugNpsiYQ1MKkgGbkwPEeTcsTCdD_u5GAvYpMJKHzeSbCL=w@mail.gmail.com> <20180524044252.GW71675@FreeBSD.org> <CAPrugNoVPCbB0qTY=Z1dwCZ%2BbCbVbA1d5b0-tw5qaPxWRK0q8g@mail.gmail.com> <5B9EE208-384F-44AD-9B47-059D77FE9B34@macmic.franken.de> <CAPrugNooA9Jfx5=h8fYb5%2BKPUOjSOD_NR8QX=bBkVKCAu=96-A@mail.gmail.com> <ABB8E26D-ABAE-42E6-9A1C-FAD0E8DDA3C6@macmic.franken.de> <CAPrugNq_peOYp-1ufu8d%2BOpmspmT09kUqxV%2BvRYsHqv9tYUTGg@mail.gmail.com> <CANCZdfov%2Bb441dN7shE5JY%2BxgKnT41sVfdwrirxUDUOxkSQrJQ@mail.gmail.com>
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On Thu, May 24, 2018 at 8:58 AM, Warner Losh <imp@bsdimp.com> wrote: > > > On Thu, May 24, 2018 at 12:53 AM, Matthew Macy <mmacy@freebsd.org> wrote: >> >> On Wed, May 23, 2018 at 11:42 PM, Michael Tuexen >> <Michael.Tuexen@macmic.franken.de> wrote: >> >> On 24. May 2018, at 08:36, Matthew Macy <mmacy@freebsd.org> wrote: >> >> >> >> On Wed, May 23, 2018 at 11:35 PM, Michael Tuexen >> >> <Michael.Tuexen@macmic.franken.de> wrote: >> >>>> On 24. May 2018, at 06:51, Matthew Macy <mmacy@freebsd.org> wrote: >> >>>> >> >>>> Warnings find bugs PERIOD. Although most are not useful, I've found >> >>> Some warnings indicate bugs, some warnings are just wrong. If you >> >>> have a "may be used uninitialized" warning being a false positive, you >> >>> may silences the warning by just set it to zero in the declaration and >> >>> you silence it. Other compilers might then correctly report an >> >>> assignment without affect... >> >> >> >> I have yet to see a double assignment be flagged as assignment without >> >> effect. If it _does_ occur then we have to disable the warning on the >> >> compiler that we have less faith in. >> > Have seen it in the past in a difference project... But you miss my >> > point: >> > >> > Not all warnings indicate bugs PERIOD. Some warning are just wrong... >> >> Have you read my follow up? _Many_ Many warnings are wrong. Please >> respond to that on what the global policy should be. The value of any >> one particular instance of a warning does not merit discussion. > > > The global policy has never been 'fix all warnings no matter what.' It's > been 'Look at the warning. If it's a false positive, use judgement about > whether or not to stifle the compiler.' There are cases I've run into that > it was impossible to silence the warnings (apart form adding command line > stuff) for a particular bit of code. Do it one way gcc 4.2 complains. Do it > another clang complains. appease both and gcc 6 had heart-burn. > > So don't gratuitously commit code that fixes warnings on gcc 8. If the > warning points out a legitimate bug, then that's no brainer yes. If it's a > false positive, then it's less clear and often times many factors may need > to be weighed. Non-actionable warnings are actively detrimental to workflow. They hide real issues and lead to apathy by developers. If pacifying a warning is considered undesirable it should be disabled by default with perhaps a separate mode for enabling it. -M
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