winapi DST requirements

blah.md

Need to be able to add dynamically sized arrays as the last field of a type.

#[repr(C)] struct Foo {
    blah: Blah,
    cbSize: DWORD,
    array: [SomeType; N], // This field should be dynamically sized.
}

The user must be able to specify a value for N when creating such a type, but there must only be one such type, so that FFI functions can easily take a *const Foo or *mut Foo.

The user should be able to allocate such a type with relative ease. At a bare minimum it must be possible to easily such a type on the heap, with the size specified at runtime. Ideally it would be allocatable on the stack with a const size. As a pipe dream, it would be neat if it could be allocated on the stack with a runtime size.

I don't really care what the syntax is, as long as it is relatively sane. It's fine if it requires unsafe.