Lambda closure decomposition

lambda_decompose.cpp

#include <iostream>

template <class T> struct overload : T { using T::operator(); };
template <class T> overload(T) -> overload<T>;

int main()
{   
    auto f = [x = 1, y = 2]() { return x + y; };
    // auto [a, b] = f; // error: cannot decompose lambda closure type 'main()::<lambda()>'

    overload o { f };
    auto [a, b] = o;

    std::cout << "a: " << a << '\n';
    std::cout << "b: " << b << '\n';
}

a: 1
b: 2

Works with gcc only.