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a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=H+rGPaoJ9R3rr7zK4cuxMwlBlLpdlGUAwlQnvIZjZd8=; b=TuAvjxwjT445lMd0pA19KFC41p7wFL3HpX87iRUSwYKecaY5CUfZGct0eplp4BJ0qb XiLVR9bkLwYNAqYbnPCeCrmFMmzIYCex6DLHYCnXX+zltCNsaCLpjrQx4r/2rmFuFTxp OTWYMwGItGlUPxY9pOrHKkBQk5OsO81nPbRFSRldqVfEmFEQ19oxufnBVpuizZXjTJ3J SqcHKA6zqtjv+8GF30372iB+q1pf4m1+gNSwzQ4iPc9XGNvnJVl3zD9hoBWrYyzUvJg7 rSKHNYAEM+yVkGmxnTuKXOEZmV3wJKia/q5GQqCoZRYdoET7bWZN/1p/1d5q50/73x8u UDrQ== X-Gm-Message-State: AOAM533cWSfF1GKXDPTkXDzUnQ9dFzxyHvitaynzzfrEbImfdlf5kdde /o4zLjdIUAxY8/gXzQXC0P68KCW3n/OI9g4r+DM= X-Google-Smtp-Source: ABdhPJzOwu2wFsHHn8A1YNPfZeoFLdmnMgNDFogUYxSXdSyfkKR4RJ+IXZpEdbdh4p7RHhstmUROclNZOq0Hltp8jFg= X-Received: by 2002:a5b:40e:: with SMTP id m14mr627984ybp.33.1606261594309; Tue, 24 Nov 2020 15:46:34 -0800 (PST) MIME-Version: 1.0 References: <20201120105344.4345c14e@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> <202011201129.B13FDB3C@keescook> <20201120115142.292999b2@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> <202011220816.8B6591A@keescook> <9b57fd4914b46f38d54087d75e072d6e947cb56d.camel@HansenPartnership.com> In-Reply-To: From: Miguel Ojeda Date: Wed, 25 Nov 2020 00:46:23 +0100 Message-ID: Subject: Re: [PATCH 000/141] Fix fall-through warnings for Clang To: Finn Thain X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201124_184636_515464_638921CF X-CRM114-Status: GOOD ( 20.26 ) X-Mailman-Approved-At: Wed, 25 Nov 2020 04:56:59 -0500 X-BeenThere: linux-i3c@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: alsa-devel@alsa-project.org, linux-atm-general@lists.sourceforge.net, reiserfs-devel@vger.kernel.org, linux-iio@vger.kernel.org, linux-wireless , linux-fbdev@vger.kernel.org, dri-devel@lists.freedesktop.org, "Gustavo A. R. Silva" , James Bottomley , linux-ide@vger.kernel.org, dm-devel@redhat.com, keyrings@vger.kernel.org, linux-mtd@lists.infradead.org, GR-everest-linux-l2@marvell.com, wcn36xx@lists.infradead.org, samba-technical@lists.samba.org, linux-i3c@lists.infradead.org, linux1394-devel@lists.sourceforge.net, linux-afs@lists.infradead.org, usb-storage@lists.one-eyed-alien.net, drbd-dev@lists.linbit.com, devel@driverdev.osuosl.org, linux-cifs@vger.kernel.org, rds-devel@oss.oracle.com, Nick Desaulniers , linux-scsi@vger.kernel.org, Nathan Chancellor , linux-rdma@vger.kernel.org, oss-drivers@netronome.com, bridge@lists.linux-foundation.org, linux-security-module@vger.kernel.org, amd-gfx@lists.freedesktop.org, linux-stm32@st-md-mailman.stormreply.com, cluster-devel@redhat.com, linux-acpi@vger.kernel.org, coreteam@netfilter.org, intel-wired-lan@lists.osuosl.org, linux-input , Miguel Ojeda , Jakub Kicinski , Ext4 Developers List , Linux Media Mailing List , Kees Cook , selinux@vger.kernel.org, linux-arm-msm@vger.kernel.org, intel-gfx@lists.freedesktop.org, linux-geode@lists.infradead.org, linux-can@vger.kernel.org, linux-block@vger.kernel.org, linux-gpio@vger.kernel.org, op-tee@lists.trustedfirmware.org, linux-mediatek@lists.infradead.org, xen-devel@lists.xenproject.org, nouveau@lists.freedesktop.org, linux-hams@vger.kernel.org, ceph-devel@vger.kernel.org, virtualization@lists.linux-foundation.org, Linux ARM , linux-hwmon@vger.kernel.org, linux-watchdog@vger.kernel.org, linux-nfs@vger.kernel.org, GR-Linux-NIC-Dev@marvell.com, tipc-discussion@lists.sourceforge.net, Linux-MM , Network Development , linux-decnet-user@lists.sourceforge.net, linux-mmc@vger.kernel.org, linux-kernel , "maintainer:X86 ARCHITECTURE \(32-BIT AND 64-BIT\)" , linux-renesas-soc@vger.kernel.org, linux-sctp@vger.kernel.org, linux-usb@vger.kernel.org, netfilter-devel@vger.kernel.org, Linux Crypto Mailing List , patches@opensource.cirrus.com, Joe Perches , linux-integrity@vger.kernel.org, target-devel@vger.kernel.org, linux-hardening@vger.kernel.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-i3c" Errors-To: linux-i3c-bounces+linux-i3c=archiver.kernel.org@lists.infradead.org On Tue, Nov 24, 2020 at 1:58 AM Finn Thain wrote: > > What I meant was that you've used pessimism as if it was fact. "future mistakes that it might prevent" is neither pessimism nor states a fact. > For example, "There is no way to guess what the effect would be if the > compiler trained programmers to add a knee-jerk 'break' statement to avoid > a warning". It is only knee-jerk if you think you are infallible. > Moreover, what I meant was that preventing programmer mistakes is a > problem to be solved by development tools This warning comes from a development tool -- the compiler. > The idea that retro-fitting new > language constructs onto mature code is somehow necessary to "prevent > future mistakes" is entirely questionable. The kernel is not a frozen codebase. Further, "mature code vs. risk of change" arguments don't apply here because the semantics of the program and binary output isn't changing. > Sure. And if you put -Wimplicit-fallthrough into the Makefile and if that > leads to well-intentioned patches that cause regressions, it is partly on > you. Again: adding a `fallthrough` does not change the program semantics. If you are a maintainer and want to cross-check, compare the codegen. > Have you ever considered the overall cost of the countless > -Wpresume-incompetence flags? Yeah: negative. On the other hand, the overall cost of the countless -fI-am-infallible flags is very noticeable. > Perhaps you pay the power bill for a build farm that produces logs that > no-one reads? Perhaps you've run git bisect, knowing that the compiler > messages are not interesting? Or compiled software in using a language > that generates impenetrable messages? If so, here's a tip: > > # grep CFLAGS /etc/portage/make.conf > CFLAGS="... -Wno-all -Wno-extra ..." > CXXFLAGS="${CFLAGS}" > > Now allow me some pessimism: the hardware upgrades, gigawatt hours and > wait time attributable to obligatory static analyses are a net loss. If you really believe compiler warnings and static analysis are useless and costly, I think there is not much point in continuing the discussion. > No, it's not for me to prove that such patches don't affect code > generation. That's for the patch author and (unfortunately) for reviewers. I was not asking you to prove it. I am stating that proving it is very easy. Cheers, Miguel -- linux-i3c mailing list linux-i3c@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-i3c