Clarify that Cow::into_owned returns owned data
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r? @m-ou-se rust-highfive didn't tag this PR, so pinging you as library team lead. |
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library/alloc/src/borrow.rs
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| @@ -307,7 +306,7 @@ impl<B: ?Sized + ToOwned> Cow<'_, B> { | |||
| /// ); | |||
| /// ``` | |||
| /// | |||
| /// Calling `into_owned` on a `Cow::Owned` is a no-op: | |||
| /// Calling `into_owned` on a `Cow::Owned` returns the owned data: | |||
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I think it's important to explicitly say that it's the original owned data and doesn't involve any new allocations/newly cloned data.
Maybe something like this:
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| /// Calling `into_owned` on a `Cow::Owned` returns the owned data: | |
| /// Calling `into_owned` on a `Cow::Owned` returns the owned data unmodified, without cloning it: |
(I see that the example doesn't really show that. Maybe a better example would show that the pointer (cow.as_ptr()) doesn't change before and after into_owned().)
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I've updated the text to say that the value is moved and not cloned. I did not change the example, as the two examples demonstrate that we get the same outcome regardless of the Cow variant. Adding code to the Owned version to prove that the additional statement is true would obscure this.
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@bors r+ rollup |
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📌 Commit 9f4934e has been approved by |
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…an-DPC Clarify that `Cow::into_owned` returns owned data Two sections of the `Cow::into_owned` docs imply that `into_owned` returns a `Cow`. Clarify that it returns the underlying owned object, either cloned or extracted from the `Cow`.
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…an-DPC Clarify that `Cow::into_owned` returns owned data Two sections of the `Cow::into_owned` docs imply that `into_owned` returns a `Cow`. Clarify that it returns the underlying owned object, either cloned or extracted from the `Cow`.
This was referenced Apr 26, 2022
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…laumeGomez Rollup of 8 pull requests Successful merges: - rust-lang#94022 (Clarify that `Cow::into_owned` returns owned data) - rust-lang#94703 (Fix codegen bug in "ptx-kernel" abi related to arg passing) - rust-lang#95949 (Implement Default for AssertUnwindSafe) - rust-lang#96361 (Switch JS code to ES6) - rust-lang#96372 (Suggest calling method on nested field when struct is missing method) - rust-lang#96386 (simplify `describe_field` func in borrowck's diagnostics part) - rust-lang#96400 (Correct documentation for `Rvalue::ShallowInitBox`) - rust-lang#96415 (Remove references to git.io) Failed merges: r? `@ghost` `@rustbot` modify labels: rollup
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Two sections of the
Cow::into_owneddocs imply thatinto_ownedreturns aCow. Clarify that it returns the underlying owned object, either cloned or extracted from theCow.