Removal of exact capacity guarantee for `Vec::with_capacity()` is a breaking change

[GoldsteinE]

Link #95614
Cc @jmaargh

Location

https://doc.rust-lang.org/nightly/std/vec/struct.Vec.html#method.with_capacity

Summary

Latest stable guarantees that Vec::with_capacity() always allocates exact capacity (and this is indeed the case, since RawVec discards any extra allocated capacity). #96173 removes this guarantee. I believe this to be a breaking change requiring some further investigation.

[the8472]

Zulip discussion: https://rust-lang.zulipchat.com/#narrow/stream/219381-t-libs/topic/Vec.3A.3Awith_capacity.20promise