https://dlang.org/spec/struct.html defines
AnonStructDeclaration:
struct AggregateBody
but in this page, it's said nothing about the semantics of anonymous structs. That's a bug in the specification.
Comment #1 by dlang-bot — 2022-07-25T14:12:27Z
@ntrel created dlang/dlang.org pull request #3355 "[spec/struct] Add 'Union Literals' & 'Anonymous Structs & Unions'" fixing this issue:
- [spec/struct] Add 'Union Literals' & 'Anonymous Structs & Unions'
Fix Issue 21188 - Anonymous structs - not described.
Fix Issue 18855 - Behavior of Anonymous Union is Undocumented.
Fix: Non-overlapping union field data is not default initialized, it is
zeroed.
https://github.com/dlang/dlang.org/pull/3355