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R. Silva" , linux-kernel , alsa-devel@alsa-project.org, amd-gfx@lists.freedesktop.org, bridge@lists.linux-foundation.org, ceph-devel@vger.kernel.org, cluster-devel@redhat.com, coreteam@netfilter.org, devel@driverdev.osuosl.org, dm-devel@redhat.com, drbd-dev@lists.linbit.com, dri-devel@lists.freedesktop.org, GR-everest-linux-l2@marvell.com, GR-Linux-NIC-Dev@marvell.com, intel-gfx@lists.freedesktop.org, intel-wired-lan@lists.osuosl.org, keyrings@vger.kernel.org, linux1394-devel@lists.sourceforge.net, linux-acpi@vger.kernel.org, linux-afs@lists.infradead.org, Linux ARM , linux-arm-msm@vger.kernel.org, linux-atm-general@lists.sourceforge.net, linux-block@vger.kernel.org, linux-can@vger.kernel.org, linux-cifs@vger.kernel.org, Linux Crypto Mailing List , linux-decnet-user@lists.sourceforge.net, Ext4 Developers List , linux-fbdev@vger.kernel.org, linux-geode@lists.infradead.org, linux-gpio@vger.kernel.org, linux-hams@vger.kernel.org, linux-hwmon@vger.kernel.org, linux-i3c@lists.infradead.org, linux-ide@vger.kernel.org, linux-iio@vger.kernel.org, linux-input , linux-integrity@vger.kernel.org, linux-mediatek@lists.infradead.org, Linux Media Mailing List , linux-mmc@vger.kernel.org, Linux-MM , linux-mtd@lists.infradead.org, linux-nfs@vger.kernel.org, linux-rdma@vger.kernel.org, linux-renesas-soc@vger.kernel.org, linux-scsi@vger.kernel.org, linux-sctp@vger.kernel.org, linux-security-module@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-usb@vger.kernel.org, linux-watchdog@vger.kernel.org, linux-wireless , Network Development , netfilter-devel@vger.kernel.org, nouveau@lists.freedesktop.org, op-tee@lists.trustedfirmware.org, oss-drivers@netronome.com, patches@opensource.cirrus.com, rds-devel@oss.oracle.com, reiserfs-devel@vger.kernel.org, samba-technical@lists.samba.org, selinux@vger.kernel.org, target-devel@vger.kernel.org, tipc-discussion@lists.sourceforge.net, usb-storage@lists.one-eyed-alien.net, virtualization@lists.linux-foundation.org, wcn36xx@lists.infradead.org, "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" , xen-devel@lists.xenproject.org, linux-hardening@vger.kernel.org, Nick Desaulniers , Nathan Chancellor , Miguel Ojeda , Joe Perches Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.016598, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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