What a C `union` becomes

Decided

D-0041, settled by the language’s author: part of spec §18. Older text cites it as 18.41.

A type whose members overlap, read and written as C does it — not a Dazzle union, which is tagged (§7.5) and would promise a discriminant the C type does not have, with an exhaustive switch that means nothing. So RGFW_event comes in with all its members, e.type reads the one C would, and reading a member nobody wrote is C’s own bargain rather than something Dazzle can check. A literal may set one member, since they are the same bytes (DZ0705); the type is never defined by Dazzle, so its layout stays the header’s (§15.2)