Somewhat surprising impact of non-Sendable default values

DefaultValueConcurrency.swift

// With Strict Concurrency

class C {}

struct S {
    func f() {
        Task { // Surprisingly need `@MainActor in` here to make this correct
            await g() // Warning: Passing argument of non-sendable type 'C' into main actor-isolated context may introduce data races
        }
    }

    @MainActor func g(value: C = C()) {}
}

/// It is somewhat surprising to the reader that you must move the entire Task to MainActor to avoid this warning.
/// Nothing at the call site hints to why. Given the `await`, you would expect that any needed context hopping
/// would already happen. But that's because you can't see the `C()` in the call, since it's a default value.
///
/// You might imagine that IsolatedDefaultValues would resolve this, but it does not. I'm torn about whether it should.