On 7/5/15 8:15 AM, Artem Tarasov wrote:
OK, so there was an old bug fixed in 2.067 (https://issues.dlang.org/show_bug.cgi?id=4421) so that now unions apparently can't contain a struct that has invariants. It kinda makes sense, although I don't see why the invariants can be simply ignored, as they don't have as much importance as destructors/postblits.
More importantly, invariants are only called when you call members of a struct (or assert it). It requires actual usage of the particular union member. So already the programmer has indicated that member is valid by using it.
It is NOT valid to arbitrarily pick one member of the union and call its invariant (or call all of them).
I think this is an incorrect position D has taken -- Invariants should be called when calling members of a struct in a union. If an implicit choice must be made, then it should be an error. But it's easy to make the invariant call explicit.
-Steve
