From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jani Nikula Date: Wed, 23 Jan 2019 17:46:14 +0200 Subject: [Intel-wired-lan] [Intel-gfx] [PATCH 1/3] treewide: Lift switch variables out of switches In-Reply-To: <000001d4b32a$845e06e0$8d1a14a0$@211mainstreet.net> References: <20190123110349.35882-1-keescook@chromium.org> <20190123110349.35882-2-keescook@chromium.org> <20190123115829.GA31385@kroah.com> <874l9z31c5.fsf@intel.com> <000001d4b32a$845e06e0$8d1a14a0$@211mainstreet.net> Message-ID: <87va2f1int.fsf@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: intel-wired-lan@osuosl.org List-ID: On Wed, 23 Jan 2019, Edwin Zimmerman wrote: > On Wed, 23 Jan 2019, Jani Nikula wrote: >> On Wed, 23 Jan 2019, Greg KH wrote: >> > On Wed, Jan 23, 2019 at 03:03:47AM -0800, Kees Cook wrote: >> >> Variables declared in a switch statement before any case statements >> >> cannot be initialized, so move all instances out of the switches. >> >> After this, future always-initialized stack variables will work >> >> and not throw warnings like this: >> >> >> >> fs/fcntl.c: In function ?send_sigio_to_task?: >> >> fs/fcntl.c:738:13: warning: statement will never be executed [-Wswitch-unreachable] >> >> siginfo_t si; >> >> ^~ >> > >> > That's a pain, so this means we can't have any new variables in { } >> > scope except for at the top of a function? >> > >> > That's going to be a hard thing to keep from happening over time, as >> > this is valid C :( >> >> Not all valid C is meant to be used! ;) > > Very true. The other thing to keep in mind is the burden of enforcing > a prohibition on a valid C construct like this. It seems to me that > patch reviewers and maintainers have enough to do without forcing them > to watch for variable declarations in switch statements. Automating > this prohibition, should it be accepted, seems like a good idea to me. Considering that the treewide diffstat to fix this is: 18 files changed, 45 insertions(+), 46 deletions(-) and using the gcc plugin in question will trigger the switch-unreachable warning, I think we're good. There'll probably be the occasional declarations that pass through, and will get fixed afterwards. BR, Jani. -- Jani Nikula, Intel Open Source Graphics Center