c++ template conformance: gcc vs MS

c++ template conformance: gcc vs MS

[Mark Tall]

Hello,

I've come across a possible issue with GCC's adherence to the C++
standard for handling template code (gcc version 4.3.2 20081105 from
Fedora 10).

The following code compiles fine under GCC (using -pedantic and
-std=c++98), but fails under Microsoft's C++ 2008 SP1.

Microsoft explains this on
http://msdn.microsoft.com/en-us/library/cx7k7hcf(VS.80).aspx

Is GCC or Microsoft at fault ?


Code (from a header file):

template<typename T1>
struct get_num_type
  { typedef T1 num_type; };

template<>  // this line causes the problem
template<typename T2>
struct get_num_type< std::complex<T2> >
{ typedef T2 num_type; };

MS compilers gives:
error C2910: 'arma::get_pod_type<std::complex<_Other>>' : cannot be
explicitly specialized

Re: c++ template conformance: gcc vs MS

[Mark Tall]

[Sorry, I pasted the wrong compiler output (but for the same bug).
Below is the corrected e-mail. ]

I've come across a possible issue with GCC's adherence to the C++
standard for handling template code (gcc version 4.3.2 20081105 from
Fedora 10).

The following code compiles fine under GCC (using -pedantic and
-std=c++98), but fails under Microsoft's C++ 2008 SP1.

Microsoft explains this on
http://msdn.microsoft.com/en-us/library/cx7k7hcf(VS.80).aspx

Is GCC or Microsoft at fault ?

Code (from a header file):

template<typename T1>
struct get_num_type
 { typedef T1 num_type; };

template<>  // this line causes the problem
template<typename T2>
struct get_num_type< std::complex<T2> >
{ typedef T2 num_type; };

MS compilers gives:
error C2910: 'get_num_type<std::complex<_Other>>' : cannot be
explicitly specialized

Re: c++ template conformance: gcc vs MS

[Andrew Pinski]

On Wed, May 27, 2009 at 9:56 PM, Mark Tall <mtall.qld@gmail.com> wrote:
> [Sorry, I pasted the wrong compiler output (but for the same bug).
> Below is the corrected e-mail. ]
>
> I've come across a possible issue with GCC's adherence to the C++
> standard for handling template code (gcc version 4.3.2 20081105 from
> Fedora 10).
>
> The following code compiles fine under GCC (using -pedantic and
> -std=c++98), but fails under Microsoft's C++ 2008 SP1.
>
> Microsoft explains this on
> http://msdn.microsoft.com/en-us/library/cx7k7hcf(VS.80).aspx
>
> Is GCC or Microsoft at fault ?

GCC see http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24314 .

Thanks,
Andrew Pinski

Re: c++ template conformance: gcc vs MS

[Mark Tall]

2009/5/28 Andrew Pinski:
>
> GCC see http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24314 .
>

hmm.. known since 2005.  Is there some difficulty in fixing this ?

Re: c++ template conformance: gcc vs MS

[Daniel Berlin]

On Wed, May 27, 2009 at 10:33 PM, Mark Tall <mtall.qld@gmail.com> wrote:
> 2009/5/28 Andrew Pinski:
>>
>> GCC see http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24314 .
>>
>
> hmm.. known since 2005.  Is there some difficulty in fixing this ?
>

More likely it's pretty rare so nobody has gotten itchy enough to
scratch that part of the code :)

I'm sure if you wanted to take a gander nobody would stop you :)