On Wed, 23 Jan 2019, Greg KH <gre...@linuxfoundation.org> 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! ;) Anyway, I think you're mistaking the limitation to arbitrary blocks while it's only about the switch block IIUC. Can't have: switch (i) { int j; case 0: /* ... */ } because it can't be turned into: switch (i) { int j = 0; /* not valid C */ case 0: /* ... */ } but can have e.g.: switch (i) { case 0: { int j = 0; /* ... */ } } I think Kees' approach of moving such variable declarations to the enclosing block scope is better than adding another nesting block. BR, Jani. -- Jani Nikula, Intel Open Source Graphics Center _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel