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From:   David Laight <David.Laight@ACULAB.COM>
To:     'Kees Cook' <keescook@chromium.org>
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        "'linux@rasmusvillemoes.dk'" <linux@rasmusvillemoes.dk>,
        'Steven Rostedt' <rostedt@goodmis.org>,
        "'bvanassche@acm.org'" <bvanassche@acm.org>,
        "torvalds@linux-foundation.org" <torvalds@linux-foundation.org>,
        "Nathan Chancellor" <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Arnd Bergmann <arnd@arndb.de>,
        "akpm@linux-foundation.org" <akpm@linux-foundation.org>
Subject: RE: [PATCH next] compiler.h: Move __is_constexpr() to compiler.h.
Thread-Topic: [PATCH next] compiler.h: Move __is_constexpr() to compiler.h.
Thread-Index: Adn1PNrdhhFKapOtSdeAhH/r8REupwACvOgAAAIu+xA=
Date:   Mon, 2 Oct 2023 16:53:34 +0000
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 <202310020947.CAF558C6@keescook>
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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@med.uni-goettingen.de>
> > - */
> > -#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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