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From: David Laight <David.Laight@ACULAB.COM>
To: 'Rasmus Villemoes' <linux@rasmusvillemoes.dk>,
	Kees Cook <keescook@chromium.org>,
	Jonathan Corbet <corbet@lwn.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	Martin Uecker <Martin.Uecker@med.uni-goettingen.de>,
	Ingo Molnar <mingo@kernel.org>,
	Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>,
	Rikard Falkeborn <rikard.falkeborn@gmail.com>,
	Arnd Bergmann <arnd@arndb.de>,
	"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
	Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
	Andrew Morton <akpm@linux-foundation.org>,
	Andy Shevchenko <andy.shevchenko@gmail.com>,
	Nick Desaulniers <ndesaulniers@google.com>,
	"Gustavo A. R. Silva" <gustavoars@kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-hardening@vger.kernel.org"
	<linux-hardening@vger.kernel.org>
Subject: RE: [PATCH] linux/const.h: Explain how __is_constexpr() works
Date: Wed, 2 Feb 2022 08:49:33 +0000	[thread overview]
Message-ID: <8e166131c01b4fbc83a1ca95b83bc362@AcuMS.aculab.com> (raw)
In-Reply-To: <dc86fdf7-3202-e836-6f71-af1e2458b105@rasmusvillemoes.dk>

From: Rasmus Villemoes
> Sent: 01 February 2022 13:06
...
> > + * - The C standard defines an "integer constant expression" as different
> > + *   from a "null pointer constant" (an integer constant 0 pointer).
> 
> I don't see the point of this bullet. Yes, an ICE is a distinct concept
> from a null pointer constant, obviously. One is defined in terms of the
> other - and your parenthesis is not an accurate paraphrase of the
> definition of a null pointer constant.

From what I remember a "null pointer constant" is in "integer constant
expression with value 0 cast to a pointer type".
So (void *)(1-1) is just as valid as (void *)0.

Not sure any of it is relevant here.

	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)


  parent reply	other threads:[~2022-02-02  8:49 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-01-31 20:43 [PATCH] linux/const.h: Explain how __is_constexpr() works Kees Cook
2022-01-31 21:26 ` Gustavo A. R. Silva
2022-02-01 12:01 ` Jani Nikula
2022-02-01 13:05 ` Rasmus Villemoes
2022-02-01 15:09   ` Matthew Wilcox
2022-02-02  8:49   ` David Laight [this message]
2022-02-02 15:43     ` Uecker, Martin
2022-02-02 20:14       ` Miguel Ojeda
2022-02-02 16:19 ` David Laight
2022-02-02 20:13   ` Miguel Ojeda
2022-02-02 22:20     ` David Laight
2022-02-02 23:01       ` Miguel Ojeda
2022-02-02 23:08         ` Nick Desaulniers
2022-02-02 20:44   ` Rasmus Villemoes
2022-02-02 22:42     ` David Laight
2022-02-03  0:28       ` Miguel Ojeda
2022-02-02 20:43 ` Miguel Ojeda
2022-02-03  9:25   ` David Laight

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