前向类模板声明中的 MSVC 阻塞

Question

MSVC fails to compile

#include <iostream>

template<int N, int = N>
struct A;

template<int, int V>
struct A{static constexpr int VALUE = V;};

int main() {
  A<1> a;
  std::cout << a.VALUE;
}

Answer 1

It was a bug in MSVC manifested up to compiler version 19.22, and fixed in 19.23. Demo: https://gcc.godbolt.org/z/occvKEfc3