Use Borrow for binary_search and contains methods in the standard library #37761

christophebiocca · 2016-11-14T04:44:02Z

Fixes all standard library methods in #32822 that can be fixed without backwards compatibility issues.

rust-highfive · 2016-11-14T04:44:16Z

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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 Due to the way GitHub handles out-of-date commits, this should also make it reasonably obvious what issues have or haven't been addressed.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.

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bluss · 2016-11-14T08:45:09Z

src/libcollections/linked_list.rs

    {
-        self.iter().any(|e| e == x)
+        self.iter().any(|e| e.borrow() == x)
    }


There's another choice isn't there, to use fn contains<Q: ?Sized>(&self, x: &Q) -> bool where T: PartialEq<Q> instead? I think that is more flexible than using Borrow.

Yes, that seems like it would work better for all the contains implementations, given that anyone who implements Borrow<Q> usually implements PartialEq<Q>. Bit of tunnel vision on my part given the issue description.

The binary searches still do need to use Borrow (unless Ord<RHS> were to become a thing).

bluss · 2016-11-14T15:31:37Z

The test failure looks legit unfortunately — so that is a hint that it can cause type inference-related regressions. Should probably get a crater run when it's ready.

alexcrichton · 2016-11-14T20:02:14Z

Thanks for the PR! I've started a crater run to evaluate the impact across the ecosystem here.

alexcrichton · 2016-11-15T15:26:27Z

Unfortunately crater turned up with 28 regressions, so we may not be able to make this change :(

bluss · 2016-11-15T16:40:25Z

@alexcrichton Note other comments, about revising the PR to use PartialEq for contains.

I guess with crates having code such as .contains(&"down.sql".into()) there's not much hope for that one either..

christophebiocca · 2016-11-15T17:36:32Z

The type-inference regression will still occur, so I suspect this new code will cause essentially the same regressions.

jethrogb · 2016-11-15T23:05:16Z

PartialEq has a default type parameter though?

Edit: just tested this (playpen), not sure why that's not sufficient.

bluss · 2016-11-15T23:14:01Z

There are no regressions due to .binary_search in the crater root regressions. Then, a minority is due to type inference failure or coercion failure when using .contains().

The absolute majority of the root regressions are due to an unrelated error:

curl: (56) GnuTLS recv error (-54): Error in the pull function.

[taskcluster 2016-11-15 00:23:23.175Z] === Task Finished ===

[taskcluster 2016-11-15 00:23:23.176Z] Unsuccessful task run with exit code: 56 completed in 2.348 seconds

alexcrichton · 2016-11-17T00:20:08Z

Crater report for current PR reports 10 regressions

BurntSushi · 2016-11-21T21:48:14Z

If we remove the changes to contains, can we still make the changes to binary_search? Of the 10 root regressions in the most recent crater report, 5 look spurious and the other 5 only appear on contains.

letheed · 2016-11-22T09:20:45Z

True. The fixes are trivial though and usually lead to code simplification:

afterparty and clapx2: remove leading &
Inflector: remove .as_ref()
diesel: remove .into()

BurntSushi · 2016-11-22T12:15:43Z

@letheed I think we should be mindful/conservative about making this change even if crater said things were all clear. If it's going to break popular crates, then I don't think we should do it, no matter how trivial the fix is.

bluss · 2016-11-22T12:51:20Z

Crater is only an indication of the issues, it's far from all Rust code in existence.

letheed · 2016-11-22T13:43:29Z

@BurntSushi And I enjoy that things don't break at every new release of Rust. Still this proposed implementation for contains has merits. It should have been the one provided from the start.
Should a dedicated issue be created and tagged rust-2-breakage-wishlist?

bluss · 2016-11-22T14:04:01Z

Can this be solved by type parameter fallback? If so, it doesn't need Rust 2.

christophebiocca · 2016-11-22T21:55:01Z

@bluss, as best as I can tell type parameter fallback defaults do not work for functions, and it isn't 100% clear to me that they ever could work for functions.

bluss · 2016-11-22T22:02:48Z

@christophebiocca Did you try the feature in #27336?

christophebiocca · 2016-11-22T22:08:04Z

#27336 (comment) seems to indicate that default parameters do not work for fn, and there isn't any PR implementing it. But I might be wrong, it seems like that feature was talked about a lot over the last 2 years.

bluss · 2016-11-22T22:13:02Z

Ok, some experiments. It is implemented for functions, because fn get<T: Default = u32>() -> T { T::default() } works as expected and falls back to the given T type.

But the example in https://is.gd/cKIj8U says that the default fallback can not be used to cover up for type inference breaks.

christophebiocca · 2016-11-27T20:48:43Z

Rebased the branch to only have the binary_search changes, since those can land on their own.

I'm not sure what we want to do for the contains changes.

alexcrichton · 2016-12-01T23:42:35Z

cc @rust-lang/libs

This is kinda unfortunate where in theory we'd want to extend multiple APIs, but backwards compatibility forces us to only extend a few. That has the risk of leading to a surprisingly inconsistent experience across the standard library. Not doing this, however, also leads to a surprise where it's something that "should work" but doesn't. I'm not entirely sure what the best resolution is here.

aturon · 2016-12-03T00:30:25Z

I think I'm in favor. My biggest worry isn't about the inconsistency (which already exists, since we have this functionality for maps but not other structures). Rather, I worry about degrading the docs experience elsewhere. Still, given that we've committed to it for maps, which are one of the most common data structures, we may as well double down (and work on improving docs across the board).

alexcrichton · 2016-12-20T01:10:58Z

@bors: r+

Discussed during triage today and decision was to move forward, thanks for being patient @christophebiocca!

bors · 2016-12-20T01:10:59Z

📌 Commit c470d4a has been approved by alexcrichton

bors · 2016-12-20T01:43:07Z

⌛ Testing commit c470d4a with merge 7bad2c3...

bors · 2016-12-20T02:03:07Z

💔 Test failed - auto-mac-32-opt

alexcrichton · 2016-12-20T17:45:33Z

@bors: retry

…

On Mon, Dec 19, 2016 at 6:03 PM, bors ***@***.***> wrote: 💔 Test failed - auto-mac-32-opt <https://buildbot.rust-lang.org/builders/auto-mac-32-opt/builds/11392> — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#37761 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAD95AplOW_8e5ncjk9l8V4Qfp5kU5OPks5rJzddgaJpZM4Kw8uE> .

…efactor, r=alexcrichton Use Borrow for binary_search and contains methods in the standard library Fixes all standard library methods in rust-lang#32822 that can be fixed without backwards compatibility issues.

Rollup of 29 pull requests - Successful merges: #37761, #38006, #38131, #38150, #38158, #38171, #38208, #38215, #38236, #38245, #38289, #38302, #38315, #38346, #38388, #38395, #38398, #38418, #38432, #38451, #38463, #38468, #38470, #38471, #38472, #38478, #38486, #38493, #38498 - Failed merges: #38271, #38483

Version 1.16.0 (2017-03-16) =========================== Language -------- * Lifetimes in statics and consts default to `'static`. [RFC 1623] * [The compiler's `dead_code` lint now accounts for type aliases][38051]. * [Uninhabitable enums (those without any variants) no longer permit wildcard match patterns][38069] * [Clean up semantics of `self` in an import list][38313] * [`Self` may appear in `impl` headers][38920] * [`Self` may appear in struct expressions][39282] Compiler -------- * [`rustc` now supports `--emit=metadata`, which causes rustc to emit a `.rmeta` file containing only crate metadata][38571]. This can be used by tools like the Rust Language Service to perform metadata-only builds. * [Levenshtein based typo suggestions now work in most places, while previously they worked only for fields and sometimes for local variables][38927]. Together with the overhaul of "no resolution"/"unexpected resolution" errors (#[38154]) they result in large and systematic improvement in resolution diagnostics. * [Fix `transmute::<T, U>` where `T` requires a bigger alignment than `U`][38670] * [rustc: use -Xlinker when specifying an rpath with ',' in it][38798] * [`rustc` no longer attempts to provide "consider using an explicit lifetime" suggestions][37057]. They were inaccurate. Stabilized APIs --------------- * [`VecDeque::truncate`] * [`VecDeque::resize`] * [`String::insert_str`] * [`Duration::checked_add`] * [`Duration::checked_sub`] * [`Duration::checked_div`] * [`Duration::checked_mul`] * [`str::replacen`] * [`str::repeat`] * [`SocketAddr::is_ipv4`] * [`SocketAddr::is_ipv6`] * [`IpAddr::is_ipv4`] * [`IpAddr::is_ipv6`] * [`Vec::dedup_by`] * [`Vec::dedup_by_key`] * [`Result::unwrap_or_default`] * [`<*const T>::wrapping_offset`] * [`<*mut T>::wrapping_offset`] * `CommandExt::creation_flags` * [`File::set_permissions`] * [`String::split_off`] Libraries --------- * [`[T]::binary_search` and `[T]::binary_search_by_key` now take their argument by `Borrow` parameter][37761] * [All public types in std implement `Debug`][38006] * [`IpAddr` implements `From<Ipv4Addr>` and `From<Ipv6Addr>`][38327] * [`Ipv6Addr` implements `From<[u16; 8]>`][38131] * [Ctrl-Z returns from `Stdin.read()` when reading from the console on Windows][38274] * [std: Fix partial writes in `LineWriter`][38062] * [std: Clamp max read/write sizes on Unix][38062] * [Use more specific panic message for `&str` slicing errors][38066] * [`TcpListener::set_only_v6` is deprecated][38304]. This functionality cannot be achieved in std currently. * [`writeln!`, like `println!`, now accepts a form with no string or formatting arguments, to just print a newline][38469] * [Implement `iter::Sum` and `iter::Product` for `Result`][38580] * [Reduce the size of static data in `std_unicode::tables`][38781] * [`char::EscapeDebug`, `EscapeDefault`, `EscapeUnicode`, `CaseMappingIter`, `ToLowercase`, `ToUppercase`, implement `Display`][38909] * [`Duration` implements `Sum`][38712] * [`String` implements `ToSocketAddrs`][39048] Cargo ----- * [The `cargo check` command does a type check of a project without building it][cargo/3296] * [crates.io will display CI badges from Travis and AppVeyor, if specified in Cargo.toml][cargo/3546] * [crates.io will display categories listed in Cargo.toml][cargo/3301] * [Compilation profiles accept integer values for `debug`, in addition to `true` and `false`. These are passed to `rustc` as the value to `-C debuginfo`][cargo/3534] * [Implement `cargo --version --verbose`][cargo/3604] * [All builds now output 'dep-info' build dependencies compatible with make and ninja][cargo/3557] * [Build all workspace members with `build --all`][cargo/3511] * [Document all workspace members with `doc --all`][cargo/3515] * [Path deps outside workspace are not members][cargo/3443] Misc ---- * [`rustdoc` has a `--sysroot` argument that, like `rustc`, specifies the path to the Rust implementation][38589] * [The `armv7-linux-androideabi` target no longer enables NEON extensions, per Google's ABI guide][38413] * [The stock standard library can be compiled for Redox OS][38401] * [Rust has initial SPARC support][38726]. Tier 3. No builds available. * [Rust has experimental support for Nvidia PTX][38559]. Tier 3. No builds available. * [Fix backtraces on i686-pc-windows-gnu by disabling FPO][39379] Compatibility Notes ------------------- * [Uninhabitable enums (those without any variants) no longer permit wildcard match patterns][38069] * In this release, references to uninhabited types can not be pattern-matched. This was accidentally allowed in 1.15. * [The compiler's `dead_code` lint now accounts for type aliases][38051]. * [Ctrl-Z returns from `Stdin.read()` when reading from the console on Windows][38274] * [Clean up semantics of `self` in an import list][38313] [37057]: rust-lang/rust#37057 [37761]: rust-lang/rust#37761 [38006]: rust-lang/rust#38006 [38051]: rust-lang/rust#38051 [38062]: rust-lang/rust#38062 [38062]: rust-lang/rust#38622 [38066]: rust-lang/rust#38066 [38069]: rust-lang/rust#38069 [38131]: rust-lang/rust#38131 [38154]: rust-lang/rust#38154 [38274]: rust-lang/rust#38274 [38304]: rust-lang/rust#38304 [38313]: rust-lang/rust#38313 [38314]: rust-lang/rust#38314 [38327]: rust-lang/rust#38327 [38401]: rust-lang/rust#38401 [38413]: rust-lang/rust#38413 [38469]: rust-lang/rust#38469 [38559]: rust-lang/rust#38559 [38571]: rust-lang/rust#38571 [38580]: rust-lang/rust#38580 [38589]: rust-lang/rust#38589 [38670]: rust-lang/rust#38670 [38712]: rust-lang/rust#38712 [38726]: rust-lang/rust#38726 [38781]: rust-lang/rust#38781 [38798]: rust-lang/rust#38798 [38909]: rust-lang/rust#38909 [38920]: rust-lang/rust#38920 [38927]: rust-lang/rust#38927 [39048]: rust-lang/rust#39048 [39282]: rust-lang/rust#39282 [39379]: rust-lang/rust#39379 [`<*const T>::wrapping_offset`]: https://doc.rust-lang.org/std/primitive.pointer.html#method.wrapping_offset [`<*mut T>::wrapping_offset`]: https://doc.rust-lang.org/std/primitive.pointer.html#method.wrapping_offset [`Duration::checked_add`]: https://doc.rust-lang.org/std/time/struct.Duration.html#method.checked_add [`Duration::checked_div`]: https://doc.rust-lang.org/std/time/struct.Duration.html#method.checked_div [`Duration::checked_mul`]: https://doc.rust-lang.org/std/time/struct.Duration.html#method.checked_mul [`Duration::checked_sub`]: https://doc.rust-lang.org/std/time/struct.Duration.html#method.checked_sub [`File::set_permissions`]: https://doc.rust-lang.org/std/fs/struct.File.html#method.set_permissions [`IpAddr::is_ipv4`]: https://doc.rust-lang.org/std/net/enum.IpAddr.html#method.is_ipv4 [`IpAddr::is_ipv6`]: https://doc.rust-lang.org/std/net/enum.IpAddr.html#method.is_ipv6 [`Result::unwrap_or_default`]: https://doc.rust-lang.org/std/result/enum.Result.html#method.unwrap_or_default [`SocketAddr::is_ipv4`]: https://doc.rust-lang.org/std/net/enum.SocketAddr.html#method.is_ipv4 [`SocketAddr::is_ipv6`]: https://doc.rust-lang.org/std/net/enum.SocketAddr.html#method.is_ipv6 [`String::insert_str`]: https://doc.rust-lang.org/std/string/struct.String.html#method.insert_str [`String::split_off`]: https://doc.rust-lang.org/std/string/struct.String.html#method.split_off [`Vec::dedup_by_key`]: https://doc.rust-lang.org/std/vec/struct.Vec.html#method.dedup_by_key [`Vec::dedup_by`]: https://doc.rust-lang.org/std/vec/struct.Vec.html#method.dedup_by [`VecDeque::resize`]: https://doc.rust-lang.org/std/collections/vec_deque/struct.VecDeque.html#method.resize [`VecDeque::truncate`]: https://doc.rust-lang.org/std/collections/vec_deque/struct.VecDeque.html#method.truncate [`str::repeat`]: https://doc.rust-lang.org/std/primitive.str.html#method.repeat [`str::replacen`]: https://doc.rust-lang.org/std/primitive.str.html#method.replacen [cargo/3296]: rust-lang/cargo#3296 [cargo/3301]: rust-lang/cargo#3301 [cargo/3443]: rust-lang/cargo#3443 [cargo/3511]: rust-lang/cargo#3511 [cargo/3515]: rust-lang/cargo#3515 [cargo/3534]: rust-lang/cargo#3534 [cargo/3546]: rust-lang/cargo#3546 [cargo/3557]: rust-lang/cargo#3557 [cargo/3604]: rust-lang/cargo#3604 [RFC 1623]: https://github.com/rust-lang/rfcs/blob/master/text/1623-static.md

Remove Borrow bound from SliceExt::binary_search #37761 added a Borrow bound to `binary_search` and `binary_search_by_key` in `core::SliceExt`, but did not add it to the methods in `std::slice`. #41590 attempted to add this bound to `std::slice` but was not merged due to breakage. This PR removes the bound in `core::SliceExt`, so that these methods will have the same signature in `core` and `std`. Fixes #41561

…ig, r=alexcrichton Remove Borrow bound from SliceExt::binary_search rust-lang#37761 added a Borrow bound to `binary_search` and `binary_search_by_key` in `core::SliceExt`, but did not add it to the methods in `std::slice`. rust-lang#41590 attempted to add this bound to `std::slice` but was not merged due to breakage. This PR removes the bound in `core::SliceExt`, so that these methods will have the same signature in `core` and `std`. Fixes rust-lang#41561

…richton Remove Borrow bound from SliceExt::binary_search #37761 added a Borrow bound to `binary_search` and `binary_search_by_key` in `core::SliceExt`, but did not add it to the methods in `std::slice`. #41590 attempted to add this bound to `std::slice` but was not merged due to breakage. This PR removes the bound in `core::SliceExt`, so that these methods will have the same signature in `core` and `std`. Fixes #41561

rust-highfive assigned brson Nov 14, 2016

bluss reviewed Nov 14, 2016

View reviewed changes

alexcrichton added the T-libs-api Relevant to the library API team, which will review and decide on the PR/issue. label Nov 15, 2016

Add borrow support for slice binary search methods.

c470d4a

christophebiocca force-pushed the borrow-stdlib-fn-refactor branch 2 times, most recently from db95b4c to c470d4a Compare November 27, 2016 20:46

sfackler mentioned this pull request Dec 7, 2016

Add remove_item to Vecs #38143

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alexcrichton mentioned this pull request Dec 20, 2016

Rollup of 29 pull requests #38499

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bors merged commit c470d4a into rust-lang:master Dec 21, 2016

alexcrichton mentioned this pull request Jan 1, 2017

binary_search methods should use Borrow #32822

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brson mentioned this pull request Apr 26, 2017

SliceExt::binary_search has a different signature than slice::binary_search #41561

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circuitfox mentioned this pull request Apr 27, 2017

Fix slice binary search signature mismatch #41590

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circuitfox mentioned this pull request Aug 19, 2017

Remove Borrow bound from SliceExt::binary_search #43989

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Use Borrow for binary_search and contains methods in the standard library #37761

Use Borrow for binary_search and contains methods in the standard library #37761

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Use Borrow for binary_search and contains methods in the standard library #37761

Use Borrow for binary_search and contains methods in the standard library #37761

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