On Tue, 12 Mar 2019 20:24:47 +0300 Alexey Dobriyan <adobri...@gmail.com> wrote:
> On Mon, Mar 11, 2019 at 05:38:45PM -0700, Andrew Morton wrote:
> > On Sun, 10 Mar 2019 16:35:35 +0300 Alexey Dobriyan <adobri...@gmail.com>
> > wrote:
> >
> > > Newly added static_assert() is formally a declaration, which will give
> > > a warning if used in the middle of the function.
> > >
> > > ...
> > >
> > > --- a/Makefile
> > > +++ b/Makefile
> > > @@ -792,9 +792,6 @@ endif
> > > # arch Makefile may override CC so keep this after arch Makefile is
> > > included
> > > NOSTDINC_FLAGS += -nostdinc -isystem $(shell $(CC)
> > > -print-file-name=include)
> > >
> > > -# warn about C99 declaration after statement
> > > -KBUILD_CFLAGS += -Wdeclaration-after-statement
> > > -
> > > # Variable Length Arrays (VLAs) should not be used anywhere in the kernel
> > > KBUILD_CFLAGS += $(call cc-option,-Wvla)
> >
> > I do wish your changelogs were more elaborate :(
>
> > So the proposal is to disable -Wdeclaration-after-statement in all
> > cases for all time because static_assert() doesn't work correctly?
>
> Yes. I converted 2 cases in /proc to static_assert() and you can't write
>
> {
> [code]
> static_assert()
> }
>
> without a warning because static_assert() is declaration.
> So people would move BUILD_BUG_ON() to where it doesn't belong.
Sure.
> > Surely there's something we can do to squish the static_assert() issue
> > while retaining -Wdeclaration-after-statement?
>
> It is not good in my opinion to stick to -Wdeclaration-after-statement.
Why?
> > Perhaps by making
> > static_assert() a nop if -Wdeclaration-after-statement is in use.
> > Perhaps simply by putting { } around the static_assert()?
>
> Making a statement out of it would disable current cases where it is
> placed in headers.
I think you mean cases where static_assert() is used outside functions?
We could have two versions of it, one for use inside functions, one for
use outside functions?
