const std = @import("std"); const testing = std.testing; const expect = testing.expect; const expectEqual = testing.expectEqual; test "self-referential struct through a slice of optional" { const S = struct { const Node = struct { children: []?Node, data: ?u8, fn new() Node { return Node{ .children = undefined, .data = null, }; } }; }; var n = S.Node.new(); try expect(n.data == null); }