12     static if (is(Flags!Move))  in Helpers()
14         Flags!Move flags;  in Helpers()
18         pragma(msg, "X: ", __traits(derivedMembers, Flags!Move));  in Helpers()
26         foreach (name; __traits(derivedMembers, Move))  in Flags()
41 struct Move  struct
47 enum a7815 = Move.init.flags;  argument
51 When the Move struct member is analyzed:
53 2. In Helpers!(), static if and its condition is(Flags!Move)) evaluated.
54 3. In Flags!Move, string mixin evaluates and CTFE lambda.
55 4. __traits(derivedMembers, Move) tries to see the member of Move.
57    4b. `static if (is(Flags!Move))` in Helpers!() is evaluated
58    4c. The Flags!Move instantiation is already in progress, so it cannot be resolved.
59    4d. `static if` fails because Flags!Move cannot be determined as a type.
60 5. __traits(derivedMembers, Move) returns a 1-length tuple("a").
61 6. The lambda in Flags!Move returns a string "struct Flags {...}", then
62    Flags!Move is instantiated to a new struct Flags.
63 7. Finally Move struct does not have flags member, then the `enum a7815`