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

[Carlos O'Donell <carlos at redhat dot com>]

On 01/05/2018 05:59 AM, Dmitry V. Levin wrote:
> On Fri, Jan 05, 2018 at 02:04:23PM +0100, Florian Weimer wrote:
>> 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.
> 
> I think the approach is fine.

+1

-- 
Cheers,
Carlos.