Dependency loop in tagged unions with self-referential functions

[joachimschmidt557]

Probably related to #2174:

A function in a tagged union returning the tagged union itself is marked as a dependency loop. Is it possible to resolve these dependency loops similar to #2174?

const TaggedUnion = union(enum) {
    First: u8,
    Second: fn (x: TaggedUnion) void, // Works
    Third: fn (x: TaggedUnion) TaggedUnion, // Doesn't work
    Fourth: fn (x: u8) TaggedUnion, // Doesn't work as well
};

pub fn main() void {
    const x = TaggedUnion.First;
}

[joachimschmidt557]

When using pointers, everything works:

const TaggedUnion = union(enum) {
    First: u8,
    Second: fn (x: *TaggedUnion) void, // Works
    Third: fn (x: *TaggedUnion) *TaggedUnion, // Works
    Fourth: fn (x: u8) *TaggedUnion, // Works
};

pub fn main() void {
    const x = TaggedUnion.First;
}