[Bug c++/81134] C++ partial template specialization issue

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81134

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|---                         |INVALID

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
This is not a bug, the conditional expression using ?: instantiates both
branches, so although one branch uses the terminating case, the other one
doesn't.

You can make the code valid like this:

template <int N, int  M>
struct GCD
{
   static const int value
     = std::conditional<(N>M), GCD<N%M, M>, GCD<N, M%N>>::type::value;
};

Or like this:

template <int N, int  M>
struct GCD : std::conditional<(N>M), GCD<N%M, M>, GCD<N, M%N>>::type
{ };