[Bug c++/79092] New: template: type ignored if value already instantiated

[nico at josuttis dot de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79092

            Bug ID: 79092
           Summary: template<auto>: type ignored if value already
                    instantiated
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: nico at josuttis dot de
  Target Milestone: ---

It seems for a template <auto N> the type of N is ignored if the value
already was instantiated.

The essence:
 template <auto N>
 struct A
 {
   A() {
     std::cout << "A::A(): N is "
               << typeid(N).name() << " with value: " << N << std::endl;
   }
 };

 A<42>();     
 A<4LL>();   // instantiates A<long long>
 A<42LL>();  // instantiates A<int> because we already had A<42>

Full example:
> http://melpon.org/wandbox/permlink/R3Of0JsugjVR6Qmc