string: implement From<&String> for String #59825

jsgf · 2019-04-09T20:45:58Z

Allow Strings to be created from borrowed Strings. This is mostly
to make things like passing &String to an impl Into<String>
parameter frictionless.

Fixes #59827.

rust-highfive · 2019-04-09T20:46:02Z

r? @kennytm

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kennytm · 2019-04-09T21:25:24Z

src/liballoc/string.rs

@@ -2179,6 +2179,14 @@ impl From<&str> for String {
    }
 }

+#[unstable(feature="from_ref_string", issue="59827")]


new impls are insta-stable, unfortunately.

Ah, OK. What version should I put then?

1.36.0. I don't think this PR could be merged in a day (before the coming release )

.34 would be ambitious yes; I guessed .35, but .36 is fine too.

Allow Strings to be created from borrowed Strings. This is mostly to make things like passing &String to an `impl Into<String>` parameter frictionless.

WiSaGaN · 2019-04-10T05:19:38Z

What is so special about String? Compare to things like OsString or even all owned types? Should they all implement From<&T> for T?

meithecatte · 2019-04-10T10:52:15Z

I'm not familiar with the ffi types, but the special thing about String is that it can Deref to str, which already implements From for String. This makes &string and &string[..] have the same semantics most of the time, but not always.

WiSaGaN · 2019-04-10T11:08:35Z

@NieDzejkob do you mean something similar to impl AsRef< OsStr> for OsString and impl<'a, T: ?Sized + AsRef< OsStr>> From<&'a T> for OsString ?

jsgf · 2019-04-10T18:12:35Z

@WiSaGaN I agree, there's nothing particularly special about String other than it was the case I ran into. It would make equal sense for a lot of types (and if we had specialization I might suggest a blanket default impl<T: Clone> From<&T> for T, but that might be going too far).

Dylan-DPC-zz · 2019-04-22T11:30:07Z

ping from triage @jsgf @kennytm any updates on this?

jsgf · 2019-04-22T18:26:33Z

@Dylan-DPC I wasn't planning any changes. I'm happy to do similar implementations for Vec and/or OsString if that would unblock it, but it's not clear to me that those missing are blocking objections.

WiSaGaN · 2019-04-23T01:23:13Z

I am wondering whether libs team have thought about implementing impl<T: Clone> From<&T> for T before. If we did, and the decision was not to, then what has changed since?

Centril · 2019-05-11T14:18:48Z

r? @sfackler

sfackler · 2019-05-11T14:37:35Z

I've definitely run into this impl missing, so I'm in favor!

@rfcbot fcp merge

rfcbot · 2019-05-11T14:37:36Z

Team member @sfackler has proposed to merge this. The next step is review by the rest of the tagged team members:

No concerns currently listed.

Once a majority of reviewers approve (and at most 2 approvals are outstanding), this will enter its final comment period. If you spot a major issue that hasn't been raised at any point in this process, please speak up!

See this document for info about what commands tagged team members can give me.

rfcbot · 2019-05-15T17:55:00Z

🔔 This is now entering its final comment period, as per the review above. 🔔

sfackler · 2019-05-15T18:23:56Z

@bors r+

bors · 2019-05-15T18:23:57Z

📌 Commit 08b0aca has been approved by sfackler

Centril · 2019-05-15T18:32:01Z

@bors rollup

string: implement From<&String> for String Allow Strings to be created from borrowed Strings. This is mostly to make things like passing `&String` to an `impl Into<String>` parameter frictionless. Fixes rust-lang#59827.

@ghost

Rollup of 9 pull requests Successful merges: - #59825 (string: implement From<&String> for String) - #59923 (Fix convert module's documentation links) - #60691 (Include expression to wait for to the span of Await) - #60763 (Move token tree related lexer state to a separate struct) - #60769 (Update rustc book CLI docs.) - #60811 (Bump measureme dependency to 0.3) - #60816 (README.md: Mention MSVC 2017+, not 2013(!)) - #60827 (Use `Symbol` more in lint APIs) - #60851 (Move `box` from the stable keyword to unstable keywords list) Failed merges: r? @ghost

string: implement From<&String> for String Allow Strings to be created from borrowed Strings. This is mostly to make things like passing `&String` to an `impl Into<String>` parameter frictionless. Fixes rust-lang#59827.

@ghost

Rollup of 6 pull requests Successful merges: - #59825 (string: implement From<&String> for String) - #59923 (Fix convert module's documentation links) - #60691 (Include expression to wait for to the span of Await) - #60769 (Update rustc book CLI docs.) - #60816 (README.md: Mention MSVC 2017+, not 2013(!)) - #60851 (Move `box` from the stable keyword to unstable keywords list) Failed merges: r? @ghost

Pkgsrc changes: * NetBSD/sparc64 disabling of "packed" removed ("packed" removed upstream) * Adapt src_libstd_build.rs patch, update sed'ing of .cargo-checksum.json Build verified on NetBSD 8.0/amd64. Upstream changes: Version 1.36.0 (2019-07-04) ========================== Language -------- - [Non-Lexical Lifetimes are now enabled on the 2015 edition.][59114] - [The order of traits in trait objects no longer affects the semantics of that object.][59445] e.g. `dyn Send + fmt::Debug` is now equivalent to `dyn fmt::Debug + Send`, where this was previously not the case. Libraries --------- - [`HashMap`'s implementation has been replaced with `hashbrown::HashMap` implem entation.][58623] - [`TryFromSliceError` now implements `From<Infallible>`.][60318] - [`mem::needs_drop` is now available as a const fn.][60364] - [`alloc::Layout::from_size_align_unchecked` is now available as a const fn.][6 0370] - [`String` now implements `BorrowMut<str>`.][60404] - [`io::Cursor` now implements `Default`.][60234] - [Both `NonNull::{dangling, cast}` are now const fns.][60244] - [The `alloc` crate is now stable.][59675] `alloc` allows you to use a subset of `std` (e.g. `Vec`, `Box`, `Arc`) in `#![no_std]` environments if the environment has access to heap memory allocation. - [`String` now implements `From<&String>`.][59825] - [You can now pass multiple arguments to the `dbg!` macro.][59826] `dbg!` will return a tuple of each argument when there is multiple arguments. - [`Result::{is_err, is_ok}` are now `#[must_use]` and will produce a warning if not used.][59648] Stabilized APIs --------------- - [`VecDeque::rotate_left`] - [`VecDeque::rotate_right`] - [`Iterator::copied`] - [`io::IoSlice`] - [`io::IoSliceMut`] - [`Read::read_vectored`] - [`Write::write_vectored`] - [`str::as_mut_ptr`] - [`mem::MaybeUninit`] - [`pointer::align_offset`] - [`future::Future`] - [`task::Context`] - [`task::RawWaker`] - [`task::RawWakerVTable`] - [`task::Waker`] - [`task::Poll`] Cargo ----- - [Cargo will now produce an error if you attempt to use the name of a required dependency as a feature.][cargo/6860] - [You can now pass the `--offline` flag to run cargo without accessing the netw ork.][cargo/6934] You can find further change's in [Cargo's 1.36.0 release notes][cargo-1-36-0]. Clippy ------ There have been numerous additions and fixes to clippy, see [Clippy's 1.36.0 rel ease notes][clippy-1-36-0] for more details. Misc ---- Compatibility Notes ------------------- - [`std::arch::x86::_rdtsc` returns `u64` instead of `i64`][stdsimd/559] - [`std::arch::x86_64::_mm_shuffle_ps` takes an `i32` instead of `u32` for `mask `][stdsimd/522] - With the stabilisation of `mem::MaybeUninit`, `mem::uninitialized` use is no longer recommended, and will be deprecated in 1.38.0. [60318]: rust-lang/rust#60318 [60364]: rust-lang/rust#60364 [60370]: rust-lang/rust#60370 [60404]: rust-lang/rust#60404 [60234]: rust-lang/rust#60234 [60244]: rust-lang/rust#60244 [58623]: rust-lang/rust#58623 [59648]: rust-lang/rust#59648 [59675]: rust-lang/rust#59675 [59825]: rust-lang/rust#59825 [59826]: rust-lang/rust#59826 [59445]: rust-lang/rust#59445 [59114]: rust-lang/rust#59114 [cargo/6860]: rust-lang/cargo#6860 [cargo/6934]: rust-lang/cargo#6934 [`VecDeque::rotate_left`]: https://doc.rust-lang.org/std/collections/struct.VecDeque.html#method.rotate_left [`VecDeque::rotate_right`]: https://doc.rust-lang.org/std/collections/struct.VecDeque.html#method.rotate_right [`Iterator::copied`]: https://doc.rust-lang.org/std/iter/trait.Iterator.html#tymethod.copied [`io::IoSlice`]: https://doc.rust-lang.org/std/io/struct.IoSlice.html [`io::IoSliceMut`]: https://doc.rust-lang.org/std/io/struct.IoSliceMut.html [`Read::read_vectored`]: https://doc.rust-lang.org/std/io/trait.Read.html#method.read_vectored [`Write::write_vectored`]: https://doc.rust-lang.org/std/io/trait.Write.html#method.write_vectored [`str::as_mut_ptr`]: https://doc.rust-lang.org/std/primitive.str.html#method.as_mut_ptr [`mem::MaybeUninit`]: https://doc.rust-lang.org/std/mem/union.MaybeUninit.html [`pointer::align_offset`]: https://doc.rust-lang.org/std/primitive.pointer.html#method.align_offset [`future::Future`]: https://doc.rust-lang.org/std/future/trait.Future.html [`task::Context`]: https://doc.rust-lang.org/beta/std/task/struct.Context.html [`task::RawWaker`]: https://doc.rust-lang.org/beta/std/task/struct.RawWaker.html [`task::RawWakerVTable`]: https://doc.rust-lang.org/beta/std/task/struct.RawWakerVTable.html [`task::Waker`]: https://doc.rust-lang.org/beta/std/task/struct.Waker.html [`task::Poll`]: https://doc.rust-lang.org/beta/std/task/enum.Poll.html [clippy-1-36-0]: https://github.com/rust-lang/rust-clippy/blob/master/CHANGELOG.md#rust-136 [cargo-1-36-0]: https://github.com/rust-lang/cargo/blob/master/CHANGELOG.md#cargo-136-2019-07-04 [stdsimd/522]: rust-lang/stdarch#522 [stdsimd/559]: rust-lang/stdarch#559

This change is made because of a breaking change in rustc: rust-lang/rust#59825 Signed-off-by: Valdemar Erk <v@erk.io>

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jsgf mentioned this pull request Apr 9, 2019

Add impl From<&String> for String #59827

Closed

jsgf force-pushed the from-ref-string branch from fafa735 to 41d2245 Compare April 9, 2019 21:21

kennytm added the needs-fcp This change is insta-stable, so needs a completed FCP to proceed. label Apr 9, 2019

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string: implement From<&String> for String

08b0aca

Allow Strings to be created from borrowed Strings. This is mostly to make things like passing &String to an `impl Into<String>` parameter frictionless.

jsgf force-pushed the from-ref-string branch from 41d2245 to 08b0aca Compare April 9, 2019 23:52

Centril added the relnotes Marks issues that should be documented in the release notes of the next release. label Apr 10, 2019

rust-highfive assigned sfackler and unassigned kennytm May 11, 2019

rfcbot added proposed-final-comment-period Proposed to merge/close by relevant subteam, see T-<team> label. Will enter FCP once signed off. disposition-merge This issue / PR is in PFCP or FCP with a disposition to merge it. labels May 11, 2019

Centril removed the needs-fcp This change is insta-stable, so needs a completed FCP to proceed. label May 11, 2019

rfcbot added the final-comment-period In the final comment period and will be merged soon unless new substantive objections are raised. label May 15, 2019

rfcbot removed the proposed-final-comment-period Proposed to merge/close by relevant subteam, see T-<team> label. Will enter FCP once signed off. label May 15, 2019

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 May 15, 2019

Centril mentioned this pull request May 15, 2019

Rollup of 9 pull requests #60859

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Centril mentioned this pull request May 15, 2019

Rollup of 8 pull requests #60864

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Centril mentioned this pull request May 16, 2019

Rollup of 6 pull requests #60877

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bors merged commit 08b0aca into rust-lang:master May 16, 2019

jonas-schievink mentioned this pull request May 19, 2019

String::as_ref() Into<String> type inference regression #60958

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saks mentioned this pull request May 20, 2019

fix breakage caused by impl From<&String> for String benashford/redis-async-rs#34

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rfcbot added finished-final-comment-period The final comment period is finished for this PR / Issue. and removed final-comment-period In the final comment period and will be merged soon unless new substantive objections are raised. labels May 25, 2019

95th mentioned this pull request Jun 18, 2019

Add dyn to areas of core. denoland/deno#2538

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This was referenced Jun 20, 2019

regression: type annotations required cannot resolve std::borrow::Cow<'_, str>: std::borrow::Borrow<_> #61476

Closed

Lint for &String::into(): String on final use of input string #61994

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Erk- added a commit to Erk-/lavalink.rs that referenced this pull request Jul 13, 2019

Fix compilation

678a369

This change is made because of a breaking change in rustc: rust-lang/rust#59825 Signed-off-by: Valdemar Erk <v@erk.io>

Centril added this to the 1.36 milestone Jul 21, 2019

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