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

[Rene Rebe]

On 19.02.2010, at 18:07, Cédric Venet wrote:

> 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.


Currently I just want to check the state of Clang++ and AFAICS there is currently no option to compile this kind of code anyway.

Given that even the latest GCC-4.4.x does not even warn about it at -Wall or -Wextra, only at -pedantic I'd not be surprised to see it in wide use. It's certainly not that technologically challenging to initialize a static const float or double, ...

-- 
  René Rebe, ExactCODE GmbH, Jaegerstr. 67, DE-10117 Berlin
  http://exactcode.com | http://t2-project.org | http://rene.rebe.name