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Re: [PATCH 2/2] Use static_assert for STATIC_ASSERT for C++11 onwards
- From: Richard Biener <richard dot guenther at gmail dot com>
- To: David Malcolm <dmalcolm at redhat dot com>
- Cc: Jakub Jelinek <jakub at redhat dot com>, Marek Polacek <polacek at redhat dot com>, GCC Patches <gcc-patches at gcc dot gnu dot org>
- Date: Wed, 27 Jul 2016 10:09:44 +0200
- Subject: Re: [PATCH 2/2] Use static_assert for STATIC_ASSERT for C++11 onwards
- Authentication-results: sourceware.org; auth=none
- References: <CAFiYyc0Kj6wj3PN_28ge1kpF5hemJiC=EWipSntEOBqnPbmtKw@mail.gmail.com> <1469575179-53321-1-git-send-email-dmalcolm@redhat.com> <1469575179-53321-2-git-send-email-dmalcolm@redhat.com>
On Wed, Jul 27, 2016 at 1:19 AM, David Malcolm <dmalcolm@redhat.com> wrote:
> C++11 has a
> static_assert (COND, MESSAGE)
> which gives more readable error messages for STATIC_ASSERT than our
> current implementation.
>
> This patch makes us use it if __cplusplus >= 201103L
>
> There's also a provisional static_assert (COND) in C++1z, but presumably
> we should wait until that one is fully standardized before using it.
>
> Bootstrapped®rtested on x86_64-pc-linux-gnu (in conjunction
> with the previous patch)
>
> OK for trunk?
Ok.
Richard.
> gcc/ChangeLog:
> * system.h (STATIC_ASSERT): Use static_assert if building
> with C++11 onwards.
> ---
> gcc/system.h | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/gcc/system.h b/gcc/system.h
> index 78a7da6..8a17197 100644
> --- a/gcc/system.h
> +++ b/gcc/system.h
> @@ -752,9 +752,14 @@ extern void fancy_abort (const char *, int, const char *) ATTRIBUTE_NORETURN;
> #define STATIC_CONSTANT_P(X) (false && (X))
> #endif
>
> -/* Until we can use C++11's static_assert. */
> +/* static_assert (COND, MESSAGE) is available in C++11 onwards. */
> +#if __cplusplus >= 201103L
> +#define STATIC_ASSERT(X) \
> + static_assert ((X), #X)
> +#else
> #define STATIC_ASSERT(X) \
> typedef int assertion1[(X) ? 1 : -1] ATTRIBUTE_UNUSED
> +#endif
>
> /* Provide a fake boolean type. We make no attempt to use the
> C99 _Bool, as it may not be available in the bootstrap compiler,
> --
> 1.8.5.3
>