Created on 2022-12-06.00:00:00 last changed 1 month ago
Base subobjects cannot be transparently replaced with complete objects, as specified in 6.7.3 [basic.life] bullet 8.4:
An object o1 is transparently replaceable by an object o2 if:
- ...
- neither o1 nor o2 is a potentially-overlapping subobject (6.7.2 [intro.object]), and
- ...
However, that bullet is over-reaching, because it disallows:
struct A { int n; }; struct B : A {}; B b; new (&b) B { {5} }; // New A base class does not transparently replace existing A base class due to /8.4. int k = b.n; // UB: member n of A base class is outside its lifetime
See issue 2677 for a suggested resolution.
History | |||
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Date | User | Action | Args |
2022-12-06 00:00:00 | admin | create |