Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

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

Merged
merged 3 commits into from
Jan 31, 2019

Conversation

matthiaskrgr
Copy link
Member

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
Copy link
Collaborator

r? @cramertj

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

@rust-highfive rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Dec 24, 2018
src/libcore/str/mod.rs Outdated Show resolved Hide resolved
@zackmdavis
Copy link
Member

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

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

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

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src/libcore/str/mod.rs Outdated Show resolved Hide resolved
@cramertj
Copy link
Member

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

@rust-highfive rust-highfive assigned sfackler and unassigned cramertj Dec 26, 2018
@sfackler
Copy link
Member

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

matthiaskrgr and others added 3 commits December 26, 2018 20:01
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 <[email protected]>
@kennytm kennytm added the relnotes Marks issues that should be documented in the release notes of the next release. label Dec 27, 2018
@Centril 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
@Centril
Copy link
Contributor

Centril commented Jan 12, 2019

Ping from triage, @sfackler :)

@TimNN
Copy link
Contributor

TimNN commented Jan 29, 2019

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

@sfackler
Copy link
Member

Oops!

@bors r+ rollup

@bors
Copy link
Contributor

bors commented Jan 29, 2019

📌 Commit 74e9057 has been approved by sfackler

@bors 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 added a commit to Centril/rust that referenced this pull request Jan 30, 2019
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
Copy link
Contributor

bors commented Jan 30, 2019

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

bors added a commit that referenced this pull request Jan 30, 2019
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].
@SimonSapin SimonSapin changed the title mark str::string::String.trim.* functions as #[must_use]. Mark str::trim.* functions as #[must_use]. Jan 30, 2019
@bors
Copy link
Contributor

bors commented Jan 30, 2019

💔 Test failed - status-appveyor

@bors 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
@Centril
Copy link
Contributor

Centril commented Jan 30, 2019

@bors retry

@bors 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 added a commit to Centril/rust that referenced this pull request Jan 30, 2019
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].
Centril added a commit to Centril/rust that referenced this pull request Jan 30, 2019
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].
Centril added a commit to Centril/rust that referenced this pull request Jan 30, 2019
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].
Centril added a commit to Centril/rust that referenced this pull request Jan 31, 2019
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].
bors added a commit that referenced this pull request Jan 31, 2019
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
@bors bors merged commit 74e9057 into rust-lang:master Jan 31, 2019
bors added a commit to rust-lang/rust-clippy that referenced this pull request Jan 31, 2019
netbsd-srcmastr pushed a commit to NetBSD/pkgsrc that referenced this pull request Apr 14, 2019
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
@Centril Centril added this to the 1.34 milestone Apr 26, 2019
netbsd-srcmastr pushed a commit to NetBSD/pkgsrc that referenced this pull request May 19, 2019
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
@matthiaskrgr matthiaskrgr deleted the trim_must_use branch February 29, 2020 14:13
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Labels
relnotes Marks issues that should be documented in the release notes of the next release. S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. T-libs-api Relevant to the library API team, which will review and decide on the PR/issue.
Projects
None yet
Development

Successfully merging this pull request may close these issues.

9 participants