Rollup of 4 pull requests #63738
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Rollup of 4 pull requests #63738
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Prevously the `read_to_end` implementation for `std::io::Take` used its own `limit` as a cap on the `reservation_size`. However, that could still result in an over-allocation like this: 1. Call `reader.take(5).read_to_end(&mut vec)`. 2. `read_to_end_with_reservation` reserves 5 bytes and calls `read`. 3. `read` writes 5 bytes. 4. `read_to_end_with_reservation` reserves 5 bytes and calls `read`. 5. `read` writes 0 bytes. 6. The read loop ends with `vec` having length 5 and capacity 10. The reservation of 5 bytes was correct for the read at step 2 but unnecessary for the read at step 4. By that second read, `Take::limit` is 0, but the `read_to_end_with_reservation` loop is still using the same `reservation_size` it started with. Solve this by having `read_to_end_with_reservation` take a closure, which lets it get a fresh `reservation_size` for each read. This is an implementation detail which doesn't affect any public API.
…kler avoid unnecessary reservations in std::io::Take::read_to_end Prevously the `read_to_end` implementation for `std::io::Take` used its own `limit` as a cap on the `reservation_size`. However, that could still result in an over-allocation like this: 1. Call `reader.take(5).read_to_end(&mut vec)`. 2. `read_to_end_with_reservation` reserves 5 bytes and calls `read`. 3. `read` writes 5 bytes. 4. `read_to_end_with_reservation` reserves 5 bytes and calls `read`. 5. `read` writes 0 bytes. 6. The read loop ends with `vec` having length 5 and capacity 10. The reservation of 5 bytes was correct for the read at step 2 but unnecessary for the read at step 4. By that second read, `Take::limit` is 0, but the `read_to_end_with_reservation` loop is still using the same `reservation_size` it started with. Solve this by having `read_to_end_with_reservation` take a closure, which lets it get a fresh `reservation_size` for each read. This is an implementation detail which doesn't affect any public API.
…unksexactmut, r=scottmcm Implement `nth_back` for ChunksExactMut This is a part of rust-lang#54054. r? @scottmcm
…ttmcm Fix bug in iter::Chain::size_hint `Chain::size_hint` currently ignores `self.state`, which means that the size hints of the underlying iterators are always combined regardless of the iteration state. This, of course, should only happen when the state is `ChainState::Both`.
Fix naming misspelling Fixes rust-lang#63734
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@bors r+ p=4 rollup=never |
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📌 Commit c139039 has been approved by |
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Successful merges:
nth_backfor ChunksExactMut #63265 (Implementnth_backfor ChunksExactMut)Failed merges:
r? @ghost