Re: [PATCH] support: Define support_static_assert for use from C and C++

[Florian Weimer <fweimer at redhat dot com>]

On 12/31/2017 08:23 PM, Florian Weimer wrote:
> 2017-12-31  Florian Weimer  <fweimer@redhat.com>
>
> 	* support/check.h (support_static_assert): Define.
> 	(TEST_COMPARE): Use it.
>
> diff --git a/support/check.h b/support/check.h
> index 55a6f09f42..7a3318a12a 100644
> --- a/support/check.h
> +++ b/support/check.h
> @@ -86,6 +86,13 @@ void support_test_verify_exit_impl (int status, const char *file, int line,
>      does not support reporting failures from a DSO.  */
>   void support_record_failure (void);
>   
> +/* Static assertion, under a common name for both C++ and C11.  */
> +#ifdef __cplusplus
> +# define support_static_assert static_assert
> +#else
> +# define support_static_assert _Static_assert
> +#endif
> +
>   /* Compare the two integers LEFT and RIGHT and report failure if they
>      are different.  */
>   #define TEST_COMPARE(left, right)                                       \
> @@ -96,14 +103,14 @@ void support_record_failure (void);
>       __left_type __left_value = (left);                                  \
>       __right_type __right_value = (right);                               \
>       /* Prevent use with floating-point and boolean types.  */           \
> -    _Static_assert ((__left_type) 1.0 == (__left_type) 1.5,             \
> +    support_static_assert ((__left_type) 1.0 == (__left_type) 1.5,      \
>                       "left value has floating-point type");              \
> -    _Static_assert ((__right_type) 1.0 == (__right_type) 1.5,           \
> +    support_static_assert ((__right_type) 1.0 == (__right_type) 1.5,    \
>                       "right value has floating-point type");             \
>       /* Prevent accidental use with larger-than-long long types.  */     \
> -    _Static_assert (sizeof (__left_value) <= sizeof (long long),        \
> +    support_static_assert (sizeof (__left_value) <= sizeof (long long), \
>                       "left value fits into long long");                  \
> -    _Static_assert (sizeof (__right_value) <= sizeof (long long),       \
> +    support_static_assert (sizeof (__right_value) <= sizeof (long long), \
>                       "right value fits into long long");                 \
>       /* Make sure that integer conversions does not alter the sign.   */ \
>       enum                                                                \
> @@ -117,7 +124,7 @@ void support_record_failure (void);
>                                               && (sizeof (__right_value)  \
>                                                   < sizeof (__left_value))) \
>       };                                                                  \
> -    _Static_assert (__left_is_unsigned == __right_is_unsigned           \
> +    support_static_assert (__left_is_unsigned == __right_is_unsigned    \
>                       || __unsigned_left_converts_to_wider                \
>                       || __unsigned_right_converts_to_wider,              \
>                       "integer conversions may alter sign of operands");  \

Could I please get another opinion on this patch?

I do prefer the separate support_static_assert macro, rather than 
meddling with compiler/library internals.

Thanks,
Florian