Unsafe is no longer necessary as of rustc 1.34 #488

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opened 2020-08-20 20:06:52 -05:00 by Gaelan · 2 comments

Gaelan commented

2020-08-20 20:06:52 -05:00

(Migrated from github.com)

This code (and another identical line in the same file) uses unsafe to convert a &[u8] to a &[u8; 8]: github.com/uuid-rs/uuid@f177d20151/src/lib.rs (L360)

From Rust 1.34 and on (before that, TryFrom wasn't stable), the following code compiles to the exact same assembly as the code above:

self.as_bytes()[8..16].try_into().unwrap()

Tested with rustc 1.34 and 1.45.2 on godbolt.org, with -O.

The try_into version is simpler and doesn't use unsafe, so it'd probably be a good idea to switch to that once support for Rust 1.32/33 is dropped.

This code (and another identical line in the same file) uses unsafe to convert a `&[u8]` to a `&[u8; 8]`: https://github.com/uuid-rs/uuid/blob/f177d20151f23a8beb9a75df40c736b27dead0d1/src/lib.rs#L360 From Rust 1.34 and on (before that, TryFrom wasn't stable), the following code compiles to the exact same assembly as the code above: ```rust self.as_bytes()[8..16].try_into().unwrap() ``` Tested with rustc 1.34 and 1.45.2 on godbolt.org, with `-O`. The `try_into` version is simpler and doesn't use unsafe, so it'd probably be a good idea to switch to that once support for Rust 1.32/33 is dropped.

👍 1

kinggoesgaming commented

2020-08-28 01:05:29 -05:00

(Migrated from github.com)