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From:   Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Date:   Wed, 2 Feb 2022 21:13:49 +0100
Message-ID: <CANiq72neVsdLRyLn24avMhLCaHxMEiG0bD-ZkG46O7J29FanYA@mail.gmail.com>
Subject: Re: [PATCH] linux/const.h: Explain how __is_constexpr() works
To:     David Laight <David.Laight@aculab.com>
Cc:     Kees Cook <keescook@chromium.org>,
        Jonathan Corbet <corbet@lwn.net>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Martin Uecker <Martin.Uecker@med.uni-goettingen.de>,
        Ingo Molnar <mingo@kernel.org>,
        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>
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On Wed, Feb 2, 2022 at 5:19 PM David Laight <David.Laight@aculab.com> wrote:
>
> - The conditional operator (?:) requires that both expressions have the
>   the same type (after numeric promotions).

I think you are referring to the arithmetic types case, but that one
does not apply here.

> - If the expressions have distinct non-NULL pointer types then they are both
>   cast to (void *) and the result has type 'void *'.

GCC and Clang give `void *` for this, but something like `float *` and
`int *` do not fit the constrains of the operator.

Cheers,
Miguel