false dependency loop in struct definition

[AndreaOrru]

pub fn List(comptime T: type) type {
    return u32;
}

const ElementList = List(Element);
const Element = struct {
    link: ElementList,
};

export fn entry() void {
    const listType = ElementList;
}

/home/andrea/Programming/test4.zig:5:1: error: 'ElementList' depends on itself
const ElementList = List(Element);

But if we just expand ElementList once inside Element, the dependency loop goes away.

[AndreaOrru]

Another subtle example of this (took me a while to figure out that it was this same issue).

const List = @import("std").IntrusiveLinkedList;

pub const Mailbox = struct {
    queue: ThreadQueue,      // WORKAROUND: List(Thread, "link")
};

pub const ThreadQueue = List(Thread, "link");

pub const Thread = struct {
    mailbox: Mailbox,
    link: List(Thread, "link").Node,
};

pub fn main() void {
    const ready_queue = ThreadQueue.init();
}

/home/andrea/src/thread.zig:7:5: error: 'ThreadQueue' depends on itself
pub const ThreadQueue = List(Thread, "link");