[Issue 16674] Clarify lifetime of pointer to AA entry

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=16674

--- Comment #2 from Shachar Shemesh <shachar at shemesh.biz> ---
If there is any doubt re: where AA are going, I think we should take the
opposite approach. It is easier to start with "no, this is UB", and the define
it than to go the other direction.

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