linux-kernel - RE: [PATCH v2 next] compiler.h: Move __is

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Message-ID: <321c3c0984e64e9cbd1b034755611710@AcuMS.aculab.com>
Date:   Fri, 6 Oct 2023 15:51:06 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Kees Cook' <keescook@...omium.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "'linux@...musvillemoes.dk'" <linux@...musvillemoes.dk>,
        'Steven Rostedt' <rostedt@...dmis.org>,
        "'bvanassche@....org'" <bvanassche@....org>,
        "torvalds@...ux-foundation.org" <torvalds@...ux-foundation.org>,
        "Nathan Chancellor" <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Arnd Bergmann <arnd@...db.de>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>
Subject: RE: [PATCH v2 next] compiler.h: Move __is_constexpr() to compiler.h.

It can also be defined more portably as:

#define __is_constexpr(x) \
	_Generic(0 ? (void *)((long)(x) * 0) : (int *)0, int *: 1, void *: 0)

Which doesn't rely on 'sizeof (void)' being valid.

But that is for another day.

There is also:
#define is_pointer_type(type) __is_constexpr((type)1)

	David

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