Documenting the case of Weak::upgrade returning None when the value behind the reference is missing#155049
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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.
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@zachs18 updated the comment both for Rc and Arc.
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There's also the unstable case of a
Weakcreated fromUniqueRc::downgradewhere theUniqueRchasn't yet been turned into anRc, for which the inner value hasn't been dropped or moved out, but something else currently owns it.
I suppose the same goes for the upgrades from within the new_cyclic callback. Should it become a list at this point?
Returns [None] in the following cases:
- the inner value has since been dropped or moved out
- this
Weakdoes not point to an allocation- the owning reference this
Weakis assosiated with is either not fully constructed or does not allow an upgrade.
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
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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I'm not sure what tidy does not like now. |
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You can run The specific issue here is that there is trailing whitespace on those lines. You can use You can also install a git hook so that git will error if you try to push code that fails tidy: https://rustc-dev-guide.rust-lang.org/building/suggested.html#installing-a-pre-push-hook |
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@bors squash "Extended the documentation for Arc's Weak::upgrade" |
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Unknown argument ""Extended". Did you mean to use |
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@bors squash message="Extended the documentation for Arc's Weak::upgrade" |
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🔨 7 commits were squashed into f580872. |
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…uwer Rollup of 5 pull requests Successful merges: - #154781 (Fix attribute order implementation) - #155242 (resolve: Introduce `(Local,Extern)Module` newtypes for local and external modules respectively) - #149614 (Use `MaybeDangling` in `std`) - #153178 (Add `TryFromIntError::kind` method and `IntErrorKind::NotAPowerOfTwo` variant) - #155049 (Documenting the case of `Weak::upgrade` returning `None` when the value behind the reference is missing) Failed merges: - #155308 (Make `OnDuplicate::Error` the default for attributes)
…uwer Rollup of 5 pull requests Successful merges: - #154781 (Fix attribute order implementation) - #155242 (resolve: Introduce `(Local,Extern)Module` newtypes for local and external modules respectively) - #149614 (Use `MaybeDangling` in `std`) - #153178 (Add `TryFromIntError::kind` method and `IntErrorKind::NotAPowerOfTwo` variant) - #155049 (Documenting the case of `Weak::upgrade` returning `None` when the value behind the reference is missing) Failed merges: - #155308 (Make `OnDuplicate::Error` the default for attributes)
Rollup merge of #155049 - quixoticaxis:weak-upgrade-documentation-extension, r=jhpratt Documenting the case of `Weak::upgrade` returning `None` when the value behind the reference is missing Adds a clause to the documentation of `Weak` for `Arc` which was discussed in #154936. Adds the same clause to the documentation of `Weak` for `Rc`, because the behavior is the same.
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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.