[llvm-dev] Investigating c++2a features

[Paul Tait via llvm-dev]

After several years out of c++, I'm getting back into it and a lot has
changed. I had to write an equality operator for a large struct the other
day and was looking for something (maybe a generator) to write it for me
and I came across a post mentioning c++ 20? would do this for free. So I
grabbed a copy of Clang 8 and wrote this simple program but I cannot get it
to compile. It fails with

error: only special member functions may be defaulted

#include <iostream>

struct foo {
  int x;
  int operator<=>(const foo&)=default;
};

int main() {
    foo f0 = {1}, f1 = {1};

    std::cout << ((f0 <=> f1) == 0) << std::endl;

    char ch;
    std::cin >> ch;
}

Any help appreciated
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