Mark str::trim.* functions as #[must_use]. #57106

matthiaskrgr · 2018-12-24T22:25:42Z

The functions return a reference to a new object and do not modify in-place
as the following code shows:

let s = String::from("   hello   ");
s.trim();
assert_eq!(s, "   hello   ");

The new reference should be bound to a variable as now indicated by #[must_use].

rust-highfive · 2018-12-24T22:25:45Z

r? @cramertj

(rust_highfive has picked a reviewer for you, use r? to override)

src/libcore/str/mod.rs

zackmdavis · 2018-12-24T22:51:10Z

Generalized discussion on where we want to do this is in #48926.

zackmdavis · 2018-12-25T17:31:26Z

src/libcore/str/mod.rs

@@ -3554,6 +3554,8 @@ impl str {
    ///
    /// assert_eq!("Hello\tworld", s.trim());
    /// ```
+    #[must_use = "this returns the trimmed string as a new allocation, \


I'm pretty sure trim returns a slice into the existing string and therefore doesn't allocate? (Sorry my earlier comment wasn't clearer: I linked to the must_use reason on String.replace just as an example of the reason functionality being used. Consistent language style is desirable, but we don't want to reuse exact words when that would be inaccurate.)

src/libcore/str/mod.rs

cramertj · 2018-12-26T17:55:04Z

r? @sfackler
(libs team member who was following the original issue)

sfackler · 2018-12-26T17:56:19Z

Yep, none of these return a new allocation, so the message here should be changed.

The functions return a reference to a new object and do not modify in-place as the following code shows: ```` let s = String::from(" hello "); s.trim(); assert_eq!(s, " hello "); ```` The new reference should be bound to a variable as now indicated by #[must_use].

trimmed string is returned as a slice instead of a new allocation Co-Authored-By: matthiaskrgr <matthias.krueger@famsik.de>

Centril · 2019-01-12T09:59:49Z

Ping from triage, @sfackler :)

TimNN · 2019-01-29T18:13:38Z

Ping from triage @sfackler / @rust-lang/libs: This PR requires your review.

sfackler · 2019-01-29T18:15:30Z

Oops!

@bors r+ rollup

bors · 2019-01-29T18:15:31Z

📌 Commit 74e9057 has been approved by sfackler

mark str::string::String.trim.* functions as #[must_use]. The functions return a reference to a new object and do not modify in-place as the following code shows: ```` let s = String::from(" hello "); s.trim(); assert_eq!(s, " hello "); ```` The new reference should be bound to a variable as now indicated by #[must_use].

bors · 2019-01-30T06:22:24Z

⌛ Testing commit 74e9057 with merge 01da8fe...

mark str::string::String.trim.* functions as #[must_use]. The functions return a reference to a new object and do not modify in-place as the following code shows: ```` let s = String::from(" hello "); s.trim(); assert_eq!(s, " hello "); ```` The new reference should be bound to a variable as now indicated by #[must_use].

bors · 2019-01-30T09:30:25Z

💔 Test failed - status-appveyor

Centril · 2019-01-30T09:32:29Z

@bors retry

Mark str::trim.* functions as #[must_use]. The functions return a reference to a new object and do not modify in-place as the following code shows: ```` let s = String::from(" hello "); s.trim(); assert_eq!(s, " hello "); ```` The new reference should be bound to a variable as now indicated by #[must_use].

@ghost

Rollup of 12 pull requests Successful merges: - #57008 (suggest `|` when `,` founds in invalid match value) - #57106 (Mark str::trim.* functions as #[must_use].) - #57920 (use `SOURCE_DATE_EPOCH` for man page time if set) - #57934 (Introduce into_raw_non_null on Rc and Arc) - #57971 (SGX target: improve panic & exit handling) - #57980 (Add the edition guide to the bookshelf) - #57984 (Improve bug message in check_ty) - #57999 (Add MOVBE x86 CPU feature) - #58000 (Fixes and cleanups) - #58005 (update docs for fix_start/end_matches) - #58007 (Don't panic when accessing enum variant ctor using `Self` in match) - #58008 (Pass correct arguments to places_conflict) Failed merges: r? @ghost

@matthiaskrgr

Rustup: unused trim result Caused by rust-lang/rust#57106 r? @matthiaskrgr

Pkgsrc changes: * Bump required rust version to build to 1.33.0. * Adapt patches to changed file locations. * (I worry about 32-bit ports, now that Atomic64 apparently is First-Class; this has been built on NetBSD/amd64 so far) Upstream changes: Version 1.34.0 (2019-04-11) ========================== Language -------- - [You can now use `#[deprecated = "reason"]`][58166] as a shorthand for `#[deprecated(note = "reason")]`. This was previously allowed by mistake but had no effect. - [You can now accept token streams in `#[attr()]`,`#[attr[]]`, and `#[attr{}]` procedural macros.][57367] - [You can now write `extern crate self as foo;`][57407] to import your crate's root into the extern prelude. Compiler -------- - [You can now target `riscv64imac-unknown-none-elf` and `riscv64gc-unknown-none-elf`.][58406] - [You can now enable linker plugin LTO optimisations with `-C linker-plugin-lto`.][58057] This allows rustc to compile your Rust code into LLVM bitcode allowing LLVM to perform LTO optimisations across C/C++ FFI boundaries. - [You can now target `powerpc64-unknown-freebsd`.][57809] Libraries --------- - [The trait bounds have been removed on some of `HashMap<K, V, S>`'s and `HashSet<T, S>`'s basic methods.][58370] Most notably you no longer require the `Hash` trait to create an iterator. - [The `Ord` trait bounds have been removed on some of `BinaryHeap<T>`'s basic methods.][58421] Most notably you no longer require the `Ord` trait to create an iterator. - [The methods `overflowing_neg` and `wrapping_neg` are now `const` functions for all numeric types.][58044] - [Indexing a `str` is now generic over all types that implement `SliceIndex<str>`.][57604] - [`str::trim`, `str::trim_matches`, `str::trim_{start, end}`, and `str::trim_{start, end}_matches` are now `#[must_use]`][57106] and will produce a warning if their returning type is unused. - [The methods `checked_pow`, `saturating_pow`, `wrapping_pow`, and `overflowing_pow` are now available for all numeric types.][57873] These are equivalvent to methods such as `wrapping_add` for the `pow` operation. Stabilized APIs --------------- #### std & core * [`Any::type_id`] * [`Error::type_id`] * [`atomic::AtomicI16`] * [`atomic::AtomicI32`] * [`atomic::AtomicI64`] * [`atomic::AtomicI8`] * [`atomic::AtomicU16`] * [`atomic::AtomicU32`] * [`atomic::AtomicU64`] * [`atomic::AtomicU8`] * [`convert::Infallible`] * [`convert::TryFrom`] * [`convert::TryInto`] * [`iter::from_fn`] * [`iter::successors`] * [`num::NonZeroI128`] * [`num::NonZeroI16`] * [`num::NonZeroI32`] * [`num::NonZeroI64`] * [`num::NonZeroI8`] * [`num::NonZeroIsize`] * [`slice::sort_by_cached_key`] * [`str::escape_debug`] * [`str::escape_default`] * [`str::escape_unicode`] * [`str::split_ascii_whitespace`] #### std * [`Instant::checked_add`] * [`Instant::checked_sub`] * [`SystemTime::checked_add`] * [`SystemTime::checked_sub`] Cargo ----- - [You can now use alternative registries to crates.io.][cargo/6654] Misc ---- - [You can now use the `?` operator in your documentation tests without manually adding `fn main() -> Result<(), _> {}`.][56470] Compatibility Notes ------------------- - [`Command::before_exec` is now deprecated in favor of the unsafe method `Command::pre_exec`.][58059] - [Use of `ATOMIC_{BOOL, ISIZE, USIZE}_INIT` is now deprecated.][57425] As you can now use `const` functions in `static` variables. [58370]: rust-lang/rust#58370 [58406]: rust-lang/rust#58406 [58421]: rust-lang/rust#58421 [58166]: rust-lang/rust#58166 [58044]: rust-lang/rust#58044 [58057]: rust-lang/rust#58057 [58059]: rust-lang/rust#58059 [57809]: rust-lang/rust#57809 [57873]: rust-lang/rust#57873 [57604]: rust-lang/rust#57604 [57367]: rust-lang/rust#57367 [57407]: rust-lang/rust#57407 [57425]: rust-lang/rust#57425 [57106]: rust-lang/rust#57106 [56470]: rust-lang/rust#56470 [cargo/6654]: rust-lang/cargo#6654 [`Any::type_id`]: https://doc.rust-lang.org/std/any/trait.Any.html#tymethod.type_id [`Error::type_id`]: https://doc.rust-lang.org/std/error/trait.Error.html#tymethod.type_id [`atomic::AtomicI16`]: https://doc.rust-lang.org/std/atomic/struct.AtomicI16.html [`atomic::AtomicI32`]: https://doc.rust-lang.org/std/atomic/struct.AtomicI32.html [`atomic::AtomicI64`]: https://doc.rust-lang.org/std/atomic/struct.AtomicI64.html [`atomic::AtomicI8`]: https://doc.rust-lang.org/std/atomic/struct.AtomicI8.html [`atomic::AtomicU16`]: https://doc.rust-lang.org/std/atomic/struct.AtomicU16.html [`atomic::AtomicU32`]: https://doc.rust-lang.org/std/atomic/struct.AtomicU32.html [`atomic::AtomicU64`]: https://doc.rust-lang.org/std/atomic/struct.AtomicU64.html [`atomic::AtomicU8`]: https://doc.rust-lang.org/std/atomic/struct.AtomicU8.html [`convert::Infallible`]: https://doc.rust-lang.org/std/convert/enum.Infallible.html [`convert::TryFrom`]: https://doc.rust-lang.org/std/convert/trait.TryFrom.html [`convert::TryInto`]: https://doc.rust-lang.org/std/convert/trait.TryInto.html [`iter::from_fn`]: https://doc.rust-lang.org/std/iter/fn.from_fn.html [`iter::successors`]: https://doc.rust-lang.org/std/iter/fn.successors.html [`num::NonZeroI128`]: https://doc.rust-lang.org/std/num/struct.NonZeroI128.html [`num::NonZeroI16`]: https://doc.rust-lang.org/std/num/struct.NonZeroI16.html [`num::NonZeroI32`]: https://doc.rust-lang.org/std/num/struct.NonZeroI32.html [`num::NonZeroI64`]: https://doc.rust-lang.org/std/num/struct.NonZeroI64.html [`num::NonZeroI8`]: https://doc.rust-lang.org/std/num/struct.NonZeroI8.html [`num::NonZeroIsize`]: https://doc.rust-lang.org/std/num/struct.NonZeroIsize.html [`slice::sort_by_cached_key`]: https://doc.rust-lang.org/std/slice/fn.sort_by_cached_key [`str::escape_debug`]: https://doc.rust-lang.org/std/primitive.str.html#method.escape_debug [`str::escape_default`]: https://doc.rust-lang.org/std/primitive.str.html#method.escape_default [`str::escape_unicode`]: https://doc.rust-lang.org/std/primitive.str.html#method.escape_unicode [`str::split_ascii_whitespace`]: https://doc.rust-lang.org/std/primitive.str.html#method.split_ascii_whitespace [`Instant::checked_add`]: https://doc.rust-lang.org/std/time/struct.Instant.html#method.checked_add [`Instant::checked_sub`]: https://doc.rust-lang.org/std/time/struct.Instant.html#method.checked_sub [`SystemTime::checked_add`]: https://doc.rust-lang.org/std/time/struct.SystemTime.html#method.checked_add [`SystemTime::checked_sub`]: https://doc.rust-lang.org/std/time/struct.SystemTime.html#method.checked_sub

rust-highfive assigned cramertj Dec 24, 2018

rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Dec 24, 2018

zackmdavis reviewed Dec 24, 2018

View reviewed changes

src/libcore/str/mod.rs Outdated Show resolved Hide resolved

matthiaskrgr force-pushed the trim_must_use branch from eded81a to 01f76d3 Compare December 25, 2018 15:16

zackmdavis suggested changes Dec 25, 2018

View reviewed changes

rust-highfive assigned sfackler and unassigned cramertj Dec 26, 2018

matthiaskrgr and others added 3 commits December 26, 2018 20:01

Update src/libcore/str/mod.rs, tweak must_use message

e7ce868

trimmed string is returned as a slice instead of a new allocation Co-Authored-By: matthiaskrgr <matthias.krueger@famsik.de>

modify remaining #[must_use[ messages

74e9057

matthiaskrgr force-pushed the trim_must_use branch from aa74cfc to 74e9057 Compare December 26, 2018 21:03

kennytm added the relnotes Marks issues that should be documented in the release notes of the next release. label Dec 27, 2018

Centril added the T-libs-api Relevant to the library API team, which will review and decide on the PR/issue. label Jan 10, 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 Jan 29, 2019

Centril mentioned this pull request Jan 30, 2019

Rollup of 4 pull requests #57982

Closed

SimonSapin changed the title ~~mark str::string::String.trim.* functions as #[must_use].~~ Mark str::trim.* functions as #[must_use]. Jan 30, 2019

bors added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Jan 30, 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 Jan 30, 2019

Centril mentioned this pull request Jan 30, 2019

Rollup of 4 pull requests #57991

Closed

Centril mentioned this pull request Jan 30, 2019

Rollup of 6 pull requests #57995

Closed

Centril mentioned this pull request Jan 30, 2019

Rollup of 12 pull requests #58014

Closed

Centril mentioned this pull request Jan 31, 2019

Rollup of 12 pull requests #58016

Merged

bors merged commit 74e9057 into rust-lang:master Jan 31, 2019

phansch mentioned this pull request Jan 31, 2019

Rustup: unused trim result rust-lang/rust-clippy#3727

Merged

bors added a commit to rust-lang/rust-clippy that referenced this pull request Jan 31, 2019

Auto merge of #3727 - phansch:rustup_unused_trim, r=matthiaskrgr

84dca9a

Rustup: unused trim result Caused by rust-lang/rust#57106 r? @matthiaskrgr

Centril added this to the 1.34 milestone Apr 26, 2019

matthiaskrgr deleted the trim_must_use branch February 29, 2020 14:13

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Mark str::trim.* functions as #[must_use]. #57106

Mark str::trim.* functions as #[must_use]. #57106

matthiaskrgr commented Dec 24, 2018

rust-highfive commented Dec 24, 2018

zackmdavis commented Dec 24, 2018

zackmdavis Dec 25, 2018

cramertj commented Dec 26, 2018

sfackler commented Dec 26, 2018

Centril commented Jan 12, 2019

TimNN commented Jan 29, 2019

sfackler commented Jan 29, 2019

bors commented Jan 29, 2019

bors commented Jan 30, 2019

bors commented Jan 30, 2019

Centril commented Jan 30, 2019

Mark str::trim.* functions as #[must_use]. #57106

Mark str::trim.* functions as #[must_use]. #57106

Conversation

matthiaskrgr commented Dec 24, 2018

rust-highfive commented Dec 24, 2018

zackmdavis commented Dec 24, 2018

zackmdavis Dec 25, 2018

Choose a reason for hiding this comment

cramertj commented Dec 26, 2018

sfackler commented Dec 26, 2018

Centril commented Jan 12, 2019

TimNN commented Jan 29, 2019

sfackler commented Jan 29, 2019

bors commented Jan 29, 2019

bors commented Jan 30, 2019

bors commented Jan 30, 2019

Centril commented Jan 30, 2019