[cfe-dev] error: initialized if it is a static const integral data member

[Cédric Venet]

Le 19/02/2010 17:41, Rene Rebe a écrit :
>
> On 19.02.2010, at 17:34, Douglas Gregor wrote:
>
>    
>> On Feb 19, 2010, at 7:50 AM, Rene Rebe wrote:
>>
>>      
>>> Hi all,
>>>
>>> still getting some production code to compile the next error is:
>>>
>>> test.cc:5:26: error: in-class initializer has non-integral, non-enumeration type 'double'
>>>
>>> While the type is a double in this case. This is tested in the clang testsuite:
>>>
>>> test/SemaTemplate/instantiate-static-var.cpp
>>>
>>> template<typename T>
>>> class Y {
>>> static const T value = 0; // expected-error{{'value' can only be initialized if it is a static const integral data member}}
>>> };
>>>
>>> Y<float>  fy; // expected-note{{in instantiation of template class 'class Y<float>' requested here}}
>>>
>>> G++ (even 4.4) does not even warn about this on neither -Wall, nor -Wextra, only with -pedantic. I assume due to this other POD initialization, especially of FP types will occur in quite some shipping code and thus suggest making it a warning, likewise.
>>>        
>>
>> Or they are treating it like an out-of-class initializer. It's hard to tell.
>>
>> But the code is clearly wrong, and Clang is right to diagnose it.
>>      
>
> I did not mean to remove the diagnostic, but make it a warning. Personally I find those arbitrary and artificial C++ limitations just annoying. We certainly can not expect the world's source code to be rewritten to match clang's liking when other compiler accept the code.
>
> René
>
>    

Not all compiler accept this code (i.e. MSVC). It is a good things that 
by default, clang try to be as standard compliant as possible. You can 
always have/use a dialect gnu-c++ if you want to use some extension but 
it decrease the portability of the code.

regards