4 fail_compilation/fail4421.d(16): Error: function `fail4421.U1.__postblit` destructors, postblits and invariants are not allowed in union `U1`
5 fail_compilation/fail4421.d(17): Error: destructor `fail4421.U1.~this` destructors, postblits and invariants are not allowed in union `U1`
6 fail_compilation/fail4421.d(18): Error: function `fail4421.U1.__invariant1` destructors, postblits and invariants are not allowed in union `U1`