title: C++ Constexpr member of template type
body: <p>I want to create a template class with a member which is a constexpr array. The array needs, of course, a different initialization depending on the type it is but I cannot declare the array without initializing it. The problem is that I don't know the values of array until template specialization.</p>
  
  <pre><code>//A.hpp
  template&lt;typename T&gt;
  class A {
  public:
      static constexpr T a[];
      constexpr A() {};
      ~A() {};
  }
  //B.hpp
  class B: public A&lt;int&gt; {
  public:
      constexpr B();
      ~B();
  };
  //B.cpp
  template&lt;&gt;
  constexpr int A&lt;int&gt;::a[]={1,2,3,4,5};
  B::B() {}
  B::~B() {}
  </code></pre>
  
  <p>How can I properly initialize A::a[] in B?</p>