Adding bitfields to D for C interop is nice as it will automatically match the platform’s ABI for bitfields, but I don’t understand why we would want the implementation defined nightmare for regular D bitfields. One of the most annoying things about C bitfields is that if you use them, you can’t just write your structs to disk or across the network as your format is immediately non-portable across different systems. That sucks as that’s exactly when you would want to save space with bitfields. Native D bitfields should avoid this problem.

However, you should be able to express that your struct including bitfields matches the layout of a C struct. I therefore propose that we tweak the syntax to require an extern(C) around bitfields matching C.

struct A {
    extern(C) {
        int x:3, y:2;
    }
}

Or

extern(C)
struct B {
    int x: 3, y:2;
}

And then have bitfields that aren’t extern(C) be illegal until the semantics are worked out. For example, Adam’s ideas could be good.

On Tuesday, 18 October 2022 at 03:04:52 UTC, Dave P. wrote:

For me, the more features, the better.

On Tuesday, 18 October 2022 at 03:04:52 UTC, Dave P. wrote:

With d CTFE reflection, this is easy to workaround.