[v3] libstdc++/50441

[Paolo Carlini]

Hi again,

just little more details:
> I'm currently blocked by the following issue. If I try to compile, 
> with -std=gnu++98 (the default for C++) and -pedantic-errors:
>
> template<typename T>
> struct limits;
>
> template<>
> struct limits<__int128> { };
>
> template<>
> struct limits<unsigned __int128> { };
>
> I get:
>
> a.cc:8:26: error: ISO C++ does not support ‘__int128’ for ‘type name’ 
> [-pedantic]
> a.cc:8:10: error: redefinition of ‘struct limits<__int128>’
> a.cc:5:10: error: previous definition of ‘struct limits<__int128>’
If I remove the second specialization:

template<typename T>
struct limits;

template<>
struct limits<__int128> { };

then it compiles just fine, with -pedantic and -pedantic-errors too. 
Thus, it looks like something is definitely wrong here. Well, the first 
and second line of the error message above - wrongly talking about 
__int128 instead of unsigned __int128, should also be an hint...

Thanks again,
Paolo.