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.
> 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.
> 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.
