Implement TrustedLen and TrustedRandomAccess for Range<integer>, array::IntoIter, VecDequeue's iterators#81607

the8472 · 2021-01-31T20:21:28Z

This should make some FromIterator and .zip() specializations applicable in a few more cases.

@rustbot label libs-impl

rustbot · 2021-01-31T20:21:30Z

Error: Label libs-impl can only be set by Rust team members

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rust-highfive · 2021-01-31T20:21:31Z

r? @Mark-Simulacrum

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sdroege · 2021-01-31T21:24:20Z

Ah I also had some of those locally already but wanted to finish the remaining ones first :) vec::Drain should also be possible to cover here, if I'm not mistaken.

library/alloc/src/collections/vec_deque/into_iter.rs

library/core/src/iter/range.rs

library/core/src/array/iter.rs

sdroege · 2021-02-01T08:18:07Z

vec::Drain should also be possible to cover here, if I'm not mistaken.

That's in #81617 now. On top of your PR here you could do the same for VecDeque

the8472 · 2021-02-05T20:30:26Z

Yeah, still worth mentioning in case someone wants to lift the Copy bound later

That doesn't seem to be practically feasible for TrustedRandomAccess. Doing so would require somehow getting the source into shape again after iteration to make it droppable without leaks or double-frees. This would be easy enough for internal iteration such as try_fold. But for external iteration this would either require Zip to implement Drop to do the cleanup iteration, which is a breaking change or it would require cleanup after each call to next() and similar single-step methods which would negate the benefits of TrustedRandomAccess.

I think implementing more LLVM-friendly iteration for sources with T: Drop would require yet another unsafe specialization trait similar to TrustedRandomAcces but with the additional restriction that the caller must call a cleanup method when they're done with the unchecked accesses.

That or llvm needs to be fixed in several ways. Then we could do away with most of this mess.

Mark-Simulacrum · 2021-02-12T02:20:42Z

r? @m-ou-se (possibly for further reassignment), I don't have a lot of knowledge about iterators right now and probably not the time to do a deep dive

m-ou-se · 2021-03-21T13:27:43Z

Thanks!

@bors r+

bors · 2021-03-21T13:27:45Z

📌 Commit f0313ee03f750adde3897c26ab208228da8ddc02 has been approved by m-ou-se

bors · 2021-03-21T16:16:28Z

⌛ Testing commit f0313ee03f750adde3897c26ab208228da8ddc02 with merge e4bce39493aa9786c563d386e1bbde6e26c2580e...

bors · 2021-03-21T16:21:34Z

💔 Test failed - checks-actions

m-ou-se · 2021-03-21T21:34:36Z

@bors r+

bors · 2021-03-21T21:34:38Z

📌 Commit 08a1dd2 has been approved by m-ou-se

…-things, r=m-ou-se Implement TrustedLen and TrustedRandomAccess for Range<integer>, array::IntoIter, VecDequeue's iterators This should make some `FromIterator` and `.zip()` specializations applicable in a few more cases. `@rustbot` label libs-impl

Rollup of 9 pull requests Successful merges: - rust-lang#80193 (stabilize `feature(osstring_ascii)`) - rust-lang#80771 (Make NonNull::as_ref (and friends) return refs with unbound lifetimes) - rust-lang#81607 (Implement TrustedLen and TrustedRandomAccess for Range<integer>, array::IntoIter, VecDequeue's iterators) - rust-lang#82554 (Fix invalid slice access in String::retain) - rust-lang#82686 (Move `std::sys::unix::platform` to `std::sys::unix::ext`) - rust-lang#82771 (slice: Stabilize IterMut::as_slice.) - rust-lang#83329 (Cleanup LLVM debuginfo module docs) - rust-lang#83336 (Fix ICE with `use clippy::a::b;`) - rust-lang#83350 (Download a more recent LLVM version if `src/version` is modified) Failed merges: r? `@ghost` `@rustbot` modify labels: rollup

rust-highfive assigned Mark-Simulacrum Jan 31, 2021

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the8472 force-pushed the trustedrandomaccess-all-the-things branch from 0897250 to e8908a0 Compare January 31, 2021 21:56

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the8472 force-pushed the trustedrandomaccess-all-the-things branch from e8908a0 to f0313ee Compare February 2, 2021 00:39

rust-highfive assigned m-ou-se and unassigned Mark-Simulacrum Feb 12, 2021

the8472 mentioned this pull request Feb 19, 2021

Zip may call __iterator_get_unchecked twice with the same index #82291

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the8472 added 2 commits March 21, 2021 20:41

implement TrustedLen and TrustedRandomAccess for VecDeque iterators

236c0cf

use BITS constant

1438207

the8472 force-pushed the trustedrandomaccess-all-the-things branch from f0313ee to 54c73a3 Compare March 21, 2021 19:41

the8472 added 2 commits March 21, 2021 20:43

implement TrustedRandomAccess for Ranges over int types

895d7a9

implement TrustedRandomAccess for array::IntoIter

08a1dd2

the8472 force-pushed the trustedrandomaccess-all-the-things branch from 54c73a3 to 08a1dd2 Compare March 21, 2021 19:44

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 21, 2021

Dylan-DPC-zz mentioned this pull request Mar 21, 2021

Rollup of 8 pull requests #83358

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Dylan-DPC-zz mentioned this pull request Mar 22, 2021

Rollup of 9 pull requests #83360

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bors merged commit 29a53e6 into rust-lang:master Mar 22, 2021

rustbot added this to the 1.53.0 milestone Mar 22, 2021

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