const S = struct {
    alpha: u32,
};
/// a value that ZLS cannot resolve
const unknown = unknown;

// good
const A = switch (unknown) {
    1 => S,
    else => unknown,
};

// bad
const B = switch (unknown) {
    1 => S,
    else => unreachable,
};

// bad
const C = switch (unknown) {
    1 => S,
    else => undefined,
};

// kind of works. Hover indicates that it isn't cleanly resolve to just `S`
const D = switch (unknown) {
    1 => S,
    else => @compileError(""),
};