Implement nth, last, and count for iter::Copied #69625

Stebalien · 2020-03-02T00:02:27Z

Implement nth, last and count for iter::Copied.

rust-highfive · 2020-03-02T00:02:31Z

r? @KodrAus

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Stebalien · 2020-03-02T00:02:57Z

(please wait on CI before reviewing)

src/libcore/iter/adapters/mod.rs

rust-highfive · 2020-03-02T00:09:57Z

The job mingw-check of your PR failed (pretty log, raw log). Through arcane magic we have determined that the following fragments from the build log may contain information about the problem.

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2020-03-02T00:04:11.4324981Z ========================== Starting Command Output ===========================
2020-03-02T00:04:11.4328043Z [command]/bin/bash --noprofile --norc /home/vsts/work/_temp/2bb7fb09-aff7-494a-8f90-7da8c847a38e.sh
2020-03-02T00:04:11.4328370Z 
2020-03-02T00:04:11.4332264Z ##[section]Finishing: Disable git automatic line ending conversion
2020-03-02T00:04:11.4351844Z ##[section]Starting: Checkout rust-lang/rust@refs/pull/69625/merge to s
2020-03-02T00:04:11.4355354Z Task         : Get sources
2020-03-02T00:04:11.4355695Z Description  : Get sources from a repository. Supports Git, TfsVC, and SVN repositories.
2020-03-02T00:04:11.4355976Z Version      : 1.0.0
2020-03-02T00:04:11.4356169Z Author       : Microsoft
---
2020-03-02T00:04:12.6028594Z ##[command]git remote add origin https://github.com/rust-lang/rust
2020-03-02T00:04:12.6040292Z ##[command]git config gc.auto 0
2020-03-02T00:04:12.6046364Z ##[command]git config --get-all http.https://github.com/rust-lang/rust.extraheader
2020-03-02T00:04:12.6056015Z ##[command]git config --get-all http.proxy
2020-03-02T00:04:12.6069202Z ##[command]git -c http.extraheader="AUTHORIZATION: basic ***" fetch --force --tags --prune --progress --no-recurse-submodules --depth=2 origin +refs/heads/*:refs/remotes/origin/* +refs/pull/69625/merge:refs/remotes/pull/69625/merge
---
2020-03-02T00:09:33.9981762Z     Checking core v0.0.0 (/checkout/src/libcore)
2020-03-02T00:09:40.1638735Z error[E0520]: `nth` specializes an item from a parent `impl`, but that item is not marked `default`
2020-03-02T00:09:40.1639980Z    --> src/libcore/iter/adapters/mod.rs:351:5
2020-03-02T00:09:40.1642042Z     |
2020-03-02T00:09:40.1643857Z 315 | / impl<'a, I, T: 'a> Iterator for Cloned<I>
2020-03-02T00:09:40.1644767Z 316 | | where
2020-03-02T00:09:40.1646716Z 317 | |     I: Iterator<Item = &'a T>,
2020-03-02T00:09:40.1648366Z ...   |
2020-03-02T00:09:40.1649027Z 344 | |     }
2020-03-02T00:09:40.1649778Z 345 | | }
2020-03-02T00:09:40.1650686Z     | |_- parent `impl` is here
2020-03-02T00:09:40.1650686Z     | |_- parent `impl` is here
2020-03-02T00:09:40.1651224Z ...
2020-03-02T00:09:40.1651954Z 351 | /     fn nth(&mut self, n: usize) -> Option<T> {
2020-03-02T00:09:40.1653023Z 352 | |         self.it.nth(n).cloned()
2020-03-02T00:09:40.1654206Z 353 | |     }
2020-03-02T00:09:40.1655019Z     | |_____^ cannot specialize default item `nth`
2020-03-02T00:09:40.1655617Z     |
2020-03-02T00:09:40.1656351Z     = note: to specialize, `nth` in the parent `impl` must be marked `default`
2020-03-02T00:09:40.1657433Z error[E0520]: `last` specializes an item from a parent `impl`, but that item is not marked `default`
2020-03-02T00:09:40.1658721Z    --> src/libcore/iter/adapters/mod.rs:355:5
2020-03-02T00:09:40.1659279Z     |
2020-03-02T00:09:40.1659279Z     |
2020-03-02T00:09:40.1660009Z 315 | / impl<'a, I, T: 'a> Iterator for Cloned<I>
2020-03-02T00:09:40.1660853Z 316 | | where
2020-03-02T00:09:40.1662081Z 317 | |     I: Iterator<Item = &'a T>,
2020-03-02T00:09:40.1663684Z ...   |
2020-03-02T00:09:40.1664500Z 344 | |     }
2020-03-02T00:09:40.1665441Z 345 | | }
2020-03-02T00:09:40.1666340Z     | |_- parent `impl` is here
2020-03-02T00:09:40.1666340Z     | |_- parent `impl` is here
2020-03-02T00:09:40.1666929Z ...
2020-03-02T00:09:40.1667631Z 355 | /     fn last(self) -> Option<T> {
2020-03-02T00:09:40.1668485Z 356 | |         self.it.last().cloned()
2020-03-02T00:09:40.1669285Z 357 | |     }
2020-03-02T00:09:40.1670095Z     | |_____^ cannot specialize default item `last`
2020-03-02T00:09:40.1670693Z     |
2020-03-02T00:09:40.1671801Z     = note: to specialize, `last` in the parent `impl` must be marked `default`
2020-03-02T00:09:40.1672997Z error[E0520]: `count` specializes an item from a parent `impl`, but that item is not marked `default`
2020-03-02T00:09:40.1673723Z    --> src/libcore/iter/adapters/mod.rs:359:5
2020-03-02T00:09:40.1674206Z     |
2020-03-02T00:09:40.1674206Z     |
2020-03-02T00:09:40.1675066Z 315 | / impl<'a, I, T: 'a> Iterator for Cloned<I>
2020-03-02T00:09:40.1675874Z 316 | | where
2020-03-02T00:09:40.1676705Z 317 | |     I: Iterator<Item = &'a T>,
2020-03-02T00:09:40.1678274Z ...   |
2020-03-02T00:09:40.1679085Z 344 | |     }
2020-03-02T00:09:40.1679844Z 345 | | }
2020-03-02T00:09:40.1681361Z     | |_- parent `impl` is here
---
2020-03-02T00:09:45.0882645Z   local time: Mon Mar  2 00:09:45 UTC 2020
2020-03-02T00:09:45.3759517Z   network time: Mon, 02 Mar 2020 00:09:45 GMT
2020-03-02T00:09:45.3762991Z == end clock drift check ==
2020-03-02T00:09:52.5187076Z 
2020-03-02T00:09:52.5238345Z ##[error]Bash exited with code '1'.
2020-03-02T00:09:52.5253675Z ##[section]Finishing: Run build
2020-03-02T00:09:52.5302150Z ##[section]Starting: Checkout rust-lang/rust@refs/pull/69625/merge to s
2020-03-02T00:09:52.5308008Z Task         : Get sources
2020-03-02T00:09:52.5308400Z Description  : Get sources from a repository. Supports Git, TfsVC, and SVN repositories.
2020-03-02T00:09:52.5308746Z Version      : 1.0.0
2020-03-02T00:09:52.5308983Z Author       : Microsoft
2020-03-02T00:09:52.5308983Z Author       : Microsoft
2020-03-02T00:09:52.5309380Z Help         : [More Information](https://go.microsoft.com/fwlink/?LinkId=798199)
2020-03-02T00:09:52.5309817Z ==============================================================================
2020-03-02T00:09:52.9116470Z Cleaning any cached credential from repository: rust-lang/rust (GitHub)
2020-03-02T00:09:52.9163480Z ##[section]Finishing: Checkout rust-lang/rust@refs/pull/69625/merge to s
2020-03-02T00:09:52.9330413Z Cleaning up task key
2020-03-02T00:09:52.9331777Z Start cleaning up orphan processes.
2020-03-02T00:09:52.9606738Z Terminate orphan process: pid (3431) (python)
2020-03-02T00:09:52.9823774Z ##[section]Finishing: Finalize Job

I'm a bot! I can only do what humans tell me to, so if this was not helpful or you have suggestions for improvements, please ping or otherwise contact @TimNN. (Feature Requests)

Centril · 2020-03-02T00:16:48Z

We currently have a moratorium on new uses of specialization: https://forge.rust-lang.org/libs/maintaining-std.html#is-specialization-involved.

Stebalien · 2020-03-02T00:33:27Z

Got it. I'll drop this down to just specializing iter::Copied (which doesn't actually use specialization).

Stebalien · 2020-03-06T01:18:08Z

CI is passing and this should be ready for review.

Centril · 2020-03-11T08:39:49Z

r? @scottmcm

KodrAus · 2020-03-11T09:10:37Z

@bors r+ rollup

bors · 2020-03-11T09:10:38Z

📌 Commit 85cbabb has been approved by KodrAus

@ghost

Rollup of 10 pull requests Successful merges: - #66059 (mem::zeroed/uninit: panic on types that do not permit zero-initialization) - #69373 (Stabilize const for integer {to,from}_{be,le,ne}_bytes methods) - #69591 (Use TypeRelating for instantiating query responses) - #69625 (Implement nth, last, and count for iter::Copied) - #69645 (const forget tests) - #69766 (Make Point `Copy` in arithmetic documentation) - #69825 (make `mem::discriminant` const) - #69859 (fix #62456) - #69891 (Exhaustiveness checking, `Matrix::push`: recursively expand or-patterns) - #69896 (parse: Tweak the function parameter edition check) Failed merges: r? @ghost

rust-highfive assigned KodrAus Mar 2, 2020

rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Mar 2, 2020

Stebalien force-pushed the feat/iter-copy-specialize branch from fe641b8 to ea5fc97 Compare March 2, 2020 00:03

Stebalien commented Mar 2, 2020

View reviewed changes

src/libcore/iter/adapters/mod.rs Outdated Show resolved Hide resolved

Stebalien force-pushed the feat/iter-copy-specialize branch from ea5fc97 to bf5e40d Compare March 2, 2020 00:37

Stebalien changed the title ~~Specialize iter::{Copied, Cloned}~~ Specialize iter::Copied Mar 2, 2020

Stebalien changed the title ~~Specialize iter::Copied~~ Implement nth, last, and count for iter::Copied Mar 2, 2020

Implement nth, last, and count for iter::Copied

85cbabb

Stebalien force-pushed the feat/iter-copy-specialize branch from bf5e40d to 85cbabb Compare March 2, 2020 00:38

Stebalien marked this pull request as ready for review March 6, 2020 01:17

rust-highfive assigned scottmcm and unassigned KodrAus Mar 11, 2020

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Mar 11, 2020

Centril mentioned this pull request Mar 11, 2020

Rollup of 10 pull requests #69914

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bors merged commit 25091ed into rust-lang:master Mar 11, 2020

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Implement nth, last, and count for iter::Copied #69625

Implement nth, last, and count for iter::Copied #69625

Stebalien commented Mar 2, 2020 •

edited

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rust-highfive commented Mar 2, 2020

Stebalien commented Mar 2, 2020

rust-highfive commented Mar 2, 2020

Centril commented Mar 2, 2020

Stebalien commented Mar 2, 2020

Stebalien commented Mar 6, 2020

Centril commented Mar 11, 2020

KodrAus commented Mar 11, 2020

bors commented Mar 11, 2020

Implement nth, last, and count for iter::Copied #69625

Implement nth, last, and count for iter::Copied #69625

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Stebalien commented Mar 2, 2020 • edited Loading

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Stebalien commented Mar 2, 2020

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Centril commented Mar 2, 2020

Stebalien commented Mar 2, 2020

Stebalien commented Mar 6, 2020

Centril commented Mar 11, 2020

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bors commented Mar 11, 2020

Stebalien commented Mar 2, 2020 •

edited

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