Uniform initialization of an atomic struct?

Question

struct S
{
    int x;
    int y;
};

std::atomic<S> asd{{1, 2}}; // what should this be? This doesn't work

Edit: Both {{1, 2}} and ({1, 2}) work in g++, neither work in clang. Is there a workaround for clang?

Answer 1

This is clang bug 18097. Here's a long thread discussing the issue, which seems to be that clang only supports scalar types for T in atomic<T>. The C++11 standard clearly states (§29.5/1) that T can be any trivially copyable type.

Both the usages shown in the question should match this constructor

constexpr atomic(T) noexcept;

The only way I can think of working around this is to default construct atomic<S> and then use atomic::store to initialize the object.

std::atomic<S> asd;
asd.store({1,2});