Use TryInto to avoid unsafe. #507
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Gaelan
requested review from
Dylan-DPC-zz,
kinggoesgaming and
KodrAus
as code owners
Previously, to_fields and to_fields_le used unsafe to convert a &[u8] into a &[u8; 8]. Now that we're only supporting Rust versions where TryInto is stable, we can use try_into().unwrap() instead, making uuid entirely safe Rust. In release mode, the compiler detects that the slice will always be the correct size, so try_into can never fail. Thus, the unwrap is optimized out and we end up with the exact same assembly as the unsafe block. Godbolt output showing the resulting assembly: https://godbolt.org/z/nWxT6W Closes uuid-rs#488.
kinggoesgaming
requested changes
Jan 4, 2021
kinggoesgaming
approved these changes
Jan 17, 2021
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I'm submitting a(n) refactor
Description
Previously, to_fields and to_fields_le used unsafe to convert a &[u8] into a &[u8; 8]. Now that we're only supporting Rust versions where TryInto is stable, we can use try_into().unwrap() instead, making uuid entirely safe Rust.
In release mode, the compiler detects that the slice will always be the correct size, so try_into can never fail. Thus, the unwrap
is optimized out and we end up with the exact same assembly as the unsafe block.
Godbolt output showing the resulting assembly: https://godbolt.org/z/nWxT6W
Motivation
Makes UUID entirely safe Rust.
With this PR,
Tests
All existing tests pass. Doesn't add any new functionality, so that should be sufficient. Assuming the Godbolt test is consistent with what happens in the context of the larger crate, this shouldn't change the resulting binary at all.
Related Issue(s)
Closes #488.