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Forward more Iterator methods - #43074

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SimonSapin:iter
Jul 15, 2017
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Forward more Iterator methods#43074
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SimonSapin:iter

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@SimonSapin

@SimonSapinSimonSapin commented Jul 5, 2017

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This allows in more cases to take advantage of specific (possibly more optimized) impls of these methods, rather than the default one defined for all Iterators.

I also wanted to do this for &mut I and Box<I>, but that didn’t compile for two reasons:

  • To make the trait object-safe, generic methods (e.g. that take a closure parameter) have a where Self: Sized bound. But e.g. Box<I>: Sized does not imply I: Sized, and adding an additional bound in the impl is not allowed. Some for of specialization would be needed here.
  • With e.g. a F: FnMut(Self::Item) -> bool bound and a type Item = I::Item associated types, I got errors like F does not implement FnMut(I::Item) -> bool. This looks like a limitation in the trait resolution system not recognizing that Self::Item == I::Item or "propagating" that fact to FnMut bounds.

@rust-highfive

rust-highfive commented Jul 5, 2017

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Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @aturon (or someone else) soon.

If any changes to this PR are deemed necessary, please add them as extra commits. This ensures that the reviewer can see what has changed since they last reviewed the code. Due to the way GitHub handles out-of-date commits, this should also make it reasonably obvious what issues have or haven't been addressed. Large or tricky changes may require several passes of review and changes.

Please see the contribution instructions for more information.

@alexcrichtonalexcrichton added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Jul 6, 2017
@arielb1

arielb1 commented Jul 11, 2017

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Is anyone going to be reviewing this? ping @aturon.

@aturon

aturon commented Jul 11, 2017

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@bors: r+

Thanks @SimonSapin!

@bors

bors commented Jul 11, 2017

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📌 Commit 758ddeb has been approved by aturon

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bors commented Jul 12, 2017

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🔒 Merge conflict

@SimonSapin@alexcrichton
Forward more Iterator methods for str::Bytes
b90e510
These are overridden by slice::Iter
@SimonSapin@alexcrichton
Forward more Iterator methods for iter::Rev
2007987
`position` could not be implemented because calling `rposition`
on the inner iterator would require more trait bounds.
@alexcrichton

alexcrichton commented Jul 13, 2017

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@bors: r=aturon

@bors

bors commented Jul 13, 2017

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📌 Commit 2007987 has been approved by aturon

@Mark-Simulacrum

Mark-Simulacrum commented Jul 14, 2017

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@bors rollup

frewsxcv added a commit to frewsxcv/rust that referenced this pull request Jul 15, 2017
@frewsxcv
Rollup merge ofrust-lang#43074- SimonSapin:iter, r=aturon
e7a9f1b
Forward more Iterator methods
This allows in more cases to take advantage of specific (possibly more optimized) impls of these methods, rather than the default one defined for all `Iterator`s.
I also wanted to do this for `&mut I` and `Box<I>`, but that didn’t compile for two reasons:
* To make the trait object-safe, generic methods (e.g. that take a closure parameter) have a `where Self: Sized` bound. But e.g. `Box<I>: Sized` does not imply `I: Sized`, and adding an additional bound in the impl is not allowed. Some for of specialization would be needed here.
* With e.g. a `F: FnMut(Self::Item) -> bool` bound and a `type Item = I::Item` associated types, I got errors like `F does not implement FnMut(I::Item) -> bool`. This looks like a limitation in the trait resolution system not recognizing that `Self::Item == I::Item` or "propagating" that fact to `FnMut` bounds.
@frewsxcvfrewsxcv mentioned this pull request Jul 15, 2017
Merged
bors added a commit that referenced this pull request Jul 15, 2017
@bors
Auto merge of#43246- frewsxcv:rollup, r=frewsxcv
a783fe2
Rollup of 8 pull requests
- Successful merges: #43074, #43145, #43159, #43202, #43222, #43228, #43229, #43240
- Failed merges:
@bors

bors commented Jul 15, 2017

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⌛ Testing commit 2007987 with merge a783fe2...

@bors
bors merged commit 2007987 into rust-lang:masterJul 15, 2017
@SimonSapin
SimonSapin deleted the iter branch November 16, 2017 17:50
@sfanxiangsfanxiang mentioned this pull request Aug 14, 2019
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Centril added a commit to Centril/rust that referenced this pull request Sep 5, 2019
@Centril
Rollup merge ofrust-lang#63549- sfanxiang:rev-rposition, r=scottmcm
9ac90fa
Rev::rposition counts from the wrong end
Introduced in rust-lang#43074.
cc @SimonSapin
Centril added a commit to Centril/rust that referenced this pull request Sep 5, 2019
@Centril
Rollup merge ofrust-lang#63549- sfanxiang:rev-rposition, r=scottmcm
38ce687
Rev::rposition counts from the wrong end
Introduced in rust-lang#43074.
cc @SimonSapin
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