C++11 compliance: unresolved symbol when assigning a constexpr duration to a non-const local variable

[viboes]

When assigning a template static value member of type constexpr boost::chrono::duration to a non-const local variable

template <int Val, typename Type>
struct dummy
{
  typedef Type type;
  static constexpr type value{static_cast<type>(Val)};
};

void aTest(){
   auto z3 = dummy2<7,boost::chrono::hours>::value;
}

There is an unresolved symbol link error.

The reason is that the boost::chrono::duration copy constructor must be =default on c++11 so that the type can be used as a constexpr.

Removing the following declaration in boost/chrono/duration

  BOOST_CONSTEXPR duration(const duration& rhs) : rep_(rhs.rep_) {} // = default;

solves the issue.

[viboes]

Committed in trunk revision [80536].

[viboes]

Merged [80714]