[Bug c++/86246] New: Template dispatching error inside a template function

[tqchen at cs dot washington.edu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86246

            Bug ID: 86246
           Summary: Template dispatching error inside a template function
           Product: gcc
           Version: 8.0.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: tqchen at cs dot washington.edu
  Target Milestone: ---

See bellow minimum reproducible example. There is also evidence that it still
exists in gcc-8.1, gcc-7 or prior versions do not have this problem

#include <type_traits>

class MyClass {
 public:
  operator double() const {
    return 1;
  }
  template<typename T>
  operator T() const {
    static_assert(std::is_class<T>::value, "problem");
    return T();
  }
};

template<typename T>
void SetValue(const MyClass& obj, T* value) {
  //  always dispatches to operator T even if T is double
  *value = obj.operator T();
}

int main() {
  MyClass obj;
  // works fine                                                                 
  obj.operator double();
  double x;
  // error, when operator T is called in SetValue                               
  SetValue(obj, &x);
}