RE: [PATCH next] compiler.h: Move __is_constexpr() to compiler.h.

From: David Laight
Date: Mon Oct 02 2023 - 12:53:44 EST


From: Kees Cook
> Sent: 02 October 2023 17:48
>
> On Mon, Oct 02, 2023 at 02:34:05PM +0000, David Laight wrote:
> > Prior to f747e6667ebb2 __is_constexpr() was in its only user minmax.h.
> > That commit moved it to const.h - but that file just defined ULL(x) and
> > UL(x) so that constants can be defined for .S and .c files.
> > So apart from the word 'const' it wasn't really a good location.
> > Instead move the definition to compiler.h just before the similar
> > is_signed_type() and is_unsigned_type().
> > (Which were moved there by dcf8e5633e2e6)
> > This may not be a good long-term home, but the three definitions
> > belong together.
> >
...
> > diff --git a/tools/include/linux/const.h b/tools/include/linux/const.h
> > index 435ddd72d2c4..81b8aae5a855 100644
> > --- a/tools/include/linux/const.h
> > +++ b/tools/include/linux/const.h
> > @@ -3,12 +3,4 @@
> >
> > #include <vdso/const.h>
> >
> > -/*
> > - * This returns a constant expression while determining if an argument is
> > - * a constant expression, most importantly without evaluating the argument.
> > - * Glory to Martin Uecker <Martin.Uecker@xxxxxxxxxxxxxxxxxxxxx>
> > - */
> > -#define __is_constexpr(x) \
> > - (sizeof(int) == sizeof(*(8 ? ((void *)((long)(x) * 0l)) : (int *)8)))
>
> Doesn't tools/ still need its own copy somewhere?

Nothing failed to build with it removed...
I think I decided that tools actually used compiler.h.

There weren't extra definitions of is_signed_type().

David

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