Test on degree of support of decltype on various compilers

decltype-test.cc

#include <iostream>

template<typename T>
class Pointer{
  private:
    T* ptr_;
  public:
    Pointer(T* ptr): ptr_(ptr) {}
    operator T*() const {
        return ptr_;
    }
    T& operator *() const {
        return *ptr_;
    }
    T* operator ->() const {
        return ptr_;
    }
    const Pointer& operator =(const Pointer& ptr) {
        ptr_ = ptr.ptr_;
        return *this;
    }
    const Pointer& operator =(T* ptr) {
        ptr = ptr;
        return *this;
    }

    template<typename Arg>
    auto operator[](Arg index) -> decltype(this->operator*()[index]) { // GCC Passed, clang Passed, MSVC Failed
        return operator*()[index];
    }

    // template<typename Arg>
    // auto operator[](Arg index) -> decltype(operator*()[index]) { // GCC Failed, clang Passed, MSVC Passed
    //     return operator*()[index];
    // }

    // template<typename Arg>
    // auto operator[](Arg index) -> decltype((**this)[index]) { // GCC Passed, clang Passed, MSVC Failed
    //     return operator*()[index];
    // }
};

int main(){
    int array[4] {1 ,2};
    int* arrayPtr = array;
    Pointer<int*> ptr(&arrayPtr);
    std::cout << ptr[1];
}