Cannot yet mangle expression type RequiresExpr

[Quincunx271]

When using a requires-expression as a template argument such as enable_if</* requires expression */>, the compiler emits: "error: cannot yet mangle expression type RequiresExpr". Some examples:

https://godbolt.org/z/J42cg7

#include <type_traits>

int main() {
    return [](auto x,
        std::enable_if_t<requires(decltype(x) it){ +1; }, int> = 0){
            return +x;
    }(42);
}

https://godbolt.org/z/fMaye4

#include <type_traits>

template <typename T>
auto foo(T x, std::enable_if_t<requires(decltype(x) it){ +it; }, int> = 0) {
    return +x;
}

int main() {
    return foo(42);
}

Yes, I know that they can be placed in a requires clause on the lambda/function. I'm intentionally doing strange things.

---

As mentioned in the cpplang slack, "The mangling of requires expressions is yet undefined by the Itanium ABI", which is likely why this fails to compile