Documenting the case of Weak::upgrade returning None when the value behind the reference is missing#155049
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library/alloc/src/rc.rs
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| /// dropping of the inner value if successful. | ||
| /// | ||
| /// Returns [`None`] if the inner value has since been dropped. | ||
| /// Returns [`None`] if the inner value has since been dropped or moved out. |
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Technically, there is a third nightly-only case for Weak::upgrade returning None for Rc when the reference has been created by calling new_in, but I'm not sure how and whether it should be explicitely mentioned.
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new_in is the allocator_api analogue of the stable Weak::new, for which upgrade has the same behavior.
Maybe something like
Returns [
None] if the inner value has since been dropped or moved out, or if thisWeakdoes not point to an allocation.
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There's also the unstable case of a Weak created from UniqueRc::downgrade where the UniqueRc hasn't yet been turned into an Rc, for which the inner value hasn't been dropped or moved out, but something else currently owns it.
quixoticaxis
changed the title
Weak::upgrade when the value behind the reference has been moved outWeak::upgrade returning None when the value behind the reference has been moved out
Based on PR comments
Based on PR's comments
quixoticaxis
changed the title
Weak::upgrade returning None when the value behind the reference has been moved outWeak::upgrade returning None when the value behind the reference is missing
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Adds a clause to the documentation of
WeakforArcwhich was discussed in #154936.Adds the same clause to the documentation of
WeakforRc, because the behavior is the same.