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Replace str's transmute() calls with pointer casts #44657

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Sep 18, 2017
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Ixrec
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@Ixrec Ixrec commented Sep 17, 2017

After the following conversation in #rust-lang:

[14:43:50] <Ixrec> TIL the implementation of from_utf_unchecked is literally just "mem::transmute(x)"
[14:43:59] <Ixrec> no wonder people keep saying transmute is overpowered
[15:15:30] <eddyb> Ixrec: it should be a pointer cast lol
[15:15:46] <eddyb> unless it doesn't let you
[16:50:34] <Ixrec> https://play.rust-lang.org/?gist=d1e6b629ad9ec1baf64ce261c63845e6&version=stable seems like it does let me
[16:52:35] <eddyb> Ixrec: yeah that's the preferred impl
[16:52:46] <eddyb> Ixrec: it just wasn't in 1.0
[16:52:50] <eddyb> IIRC
[16:53:00] <eddyb> (something something fat pointers)

Since I already wrote half of the preferred impls in the playground, might as well make an actual PR.

After the following conversation in #rust-lang:
```
[14:43:50] <Ixrec> TIL the implementation of from_utf_unchecked is literally just "mem::transmute(x)"
[14:43:59] <Ixrec> no wonder people keep saying transmute is overpowered
[15:15:30] <eddyb> Ixrec: it should be a pointer cast lol
[15:15:46] <eddyb> unless it doesn't let you
[16:50:34] <Ixrec> https://play.rust-lang.org/?gist=d1e6b629ad9ec1baf64ce261c63845e6&version=stable seems like it does let me
[16:52:35] <eddyb> Ixrec: yeah that's the preferred impl
[16:52:46] <eddyb> Ixrec: it just wasn't in 1.0
[16:52:50] <eddyb> IIRC
[16:53:00] <eddyb> (something something fat pointers)
```
Since I already wrote half of the preferred impls in the playground, might as well make an actual PR.
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eddyb commented Sep 18, 2017

@bors r+ rollup

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bors commented Sep 18, 2017

📌 Commit 38fa340 has been approved by eddyb

alexcrichton added a commit to alexcrichton/rust that referenced this pull request Sep 18, 2017
Replace str's transmute() calls with pointer casts

After the following conversation in #rust-lang:
```
[14:43:50] <Ixrec> TIL the implementation of from_utf_unchecked is literally just "mem::transmute(x)"
[14:43:59] <Ixrec> no wonder people keep saying transmute is overpowered
[15:15:30] <eddyb> Ixrec: it should be a pointer cast lol
[15:15:46] <eddyb> unless it doesn't let you
[16:50:34] <Ixrec> https://play.rust-lang.org/?gist=d1e6b629ad9ec1baf64ce261c63845e6&version=stable seems like it does let me
[16:52:35] <eddyb> Ixrec: yeah that's the preferred impl
[16:52:46] <eddyb> Ixrec: it just wasn't in 1.0
[16:52:50] <eddyb> IIRC
[16:53:00] <eddyb> (something something fat pointers)
```
Since I already wrote half of the preferred impls in the playground, might as well make an actual PR.
bors added a commit that referenced this pull request Sep 18, 2017
Rollup of 10 pull requests

- Successful merges: #44364, #44466, #44537, #44640, #44651, #44657, #44661, #44668, #44671, #44675
- Failed merges:
@carols10cents carols10cents added the S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. label Sep 18, 2017
alexcrichton added a commit to alexcrichton/rust that referenced this pull request Sep 18, 2017
Replace str's transmute() calls with pointer casts

After the following conversation in #rust-lang:
```
[14:43:50] <Ixrec> TIL the implementation of from_utf_unchecked is literally just "mem::transmute(x)"
[14:43:59] <Ixrec> no wonder people keep saying transmute is overpowered
[15:15:30] <eddyb> Ixrec: it should be a pointer cast lol
[15:15:46] <eddyb> unless it doesn't let you
[16:50:34] <Ixrec> https://play.rust-lang.org/?gist=d1e6b629ad9ec1baf64ce261c63845e6&version=stable seems like it does let me
[16:52:35] <eddyb> Ixrec: yeah that's the preferred impl
[16:52:46] <eddyb> Ixrec: it just wasn't in 1.0
[16:52:50] <eddyb> IIRC
[16:53:00] <eddyb> (something something fat pointers)
```
Since I already wrote half of the preferred impls in the playground, might as well make an actual PR.
bors added a commit that referenced this pull request Sep 18, 2017
Rollup of 11 pull requests

- Successful merges: #44364, #44466, #44537, #44548, #44640, #44651, #44657, #44661, #44668, #44671, #44675
- Failed merges:
@bors bors merged commit 38fa340 into rust-lang:master Sep 18, 2017
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4 participants