Make closures and generators a must use types #74869

tmiasko · 2020-07-28T11:30:11Z

Warn about unused expressions with closure or generator type. This follows
existing precedence of must use annotations present on FnOnce, FnMut, Fn
traits, which already indirectly apply to closures in some cases, e.g.,:

fn f() -> impl FnOnce() {
    || {}
}

fn main() {
    // an existing warning: unused implementer of `std::ops::FnOnce` that must be used:
    f();

    // a new warning: unused closure that must be used:
    || {};
}

Closes #74691.

Warn about unused expressions with closure or generator type. This follows existing precedence of must use annotations present on `FnOnce`, `FnMut`, `Fn` traits, which already indirectly apply to closures in some cases, e.g.,: ```rust fn f() -> impl FnOnce() { || {} } fn main() { // an existing warning: unused implementer of `std::ops::FnOnce` that must be used: f(); // a new warning: unused closure that must be used: || {}; } ```

rust-highfive · 2020-07-28T11:30:14Z

r? @ecstatic-morse

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ecstatic-morse · 2020-07-29T16:34:39Z

LGTM. Thanks!

@bors r+

bors · 2020-07-29T16:34:40Z

📌 Commit 821d50a has been approved by ecstatic-morse

ecstatic-morse · 2020-07-29T16:34:51Z

@bors rollup

@ghost

…arth Rollup of 10 pull requests Successful merges: - rust-lang#74742 (Remove links to rejected errata 4406 for RFC 4291) - rust-lang#74819 (Point towards `format_spec`; it is in other direction) - rust-lang#74852 (Explain why inlining default ToString impl) - rust-lang#74869 (Make closures and generators a must use types) - rust-lang#74873 (symbol mangling: use ty::print::Print for consts) - rust-lang#74902 (Remove deprecated unstable `{Box,Rc,Arc}::into_raw_non_null` functions) - rust-lang#74904 (Fix some typos in src/librustdoc/clean/auto_trait.rs) - rust-lang#74910 (fence docs: fix example Mutex) - rust-lang#74912 (Fix broken link in unstable book `plugin`) - rust-lang#74927 (Change the target data layout to specify more values) Failed merges: r? @ghost

rphmeier · 2020-07-30T03:27:30Z

@tmiasko Thanks!

Pkgsrc changes: * Remove patches now integrated upstream, many related to SunOS / Illumos. * The LLVM fix for powerpc is also now integrated upstream. * Adapt those patches where the source has moved or parts are integrated. * The randomness patches no longer applies, and I could not find where those files went... * Provide a separate bootstrap for NetBSD/powerpc 9.0, since apparently the C++ ABI is different from 8.0. Yes, this appears to be specific to the NetBSD powerpc ports. Upstream changes: Version 1.47.0 (2020-10-08) ========================== Language -------- - [Closures will now warn when not used.][74869] Compiler -------- - [Stabilized the `-C control-flow-guard` codegen option][73893], which enables [Control Flow Guard][1.47.0-cfg] for Windows platforms, and is ignored on other platforms. - [Upgraded to LLVM 11.][73526] - [Added tier 3\* support for the `thumbv4t-none-eabi` target.][74419] - [Upgrade the FreeBSD toolchain to version 11.4][75204] - [`RUST_BACKTRACE`'s output is now more compact.][75048] \* Refer to Rust's [platform support page][forge-platform-support] for more information on Rust's tiered platform support. Libraries --------- - [`CStr` now implements `Index<RangeFrom<usize>>`.][74021] - [Traits in `std`/`core` are now implemented for arrays of any length, not just those of length less than 33.][74060] - [`ops::RangeFull` and `ops::Range` now implement Default.][73197] - [`panic::Location` now implements `Copy`, `Clone`, `Eq`, `Hash`, `Ord`, `PartialEq`, and `PartialOrd`.][73583] Stabilized APIs --------------- - [`Ident::new_raw`] - [`Range::is_empty`] - [`RangeInclusive::is_empty`] - [`Result::as_deref`] - [`Result::as_deref_mut`] - [`Vec::leak`] - [`pointer::offset_from`] - [`f32::TAU`] - [`f64::TAU`] The following previously stable APIs have now been made const. - [The `new` method for all `NonZero` integers.][73858] - [The `checked_add`,`checked_sub`,`checked_mul`,`checked_neg`, `checked_shl`, `checked_shr`, `saturating_add`, `saturating_sub`, and `saturating_mul` methods for all integers.][73858] - [The `checked_abs`, `saturating_abs`, `saturating_neg`, and `signum` for all signed integers.][73858] - [The `is_ascii_alphabetic`, `is_ascii_uppercase`, `is_ascii_lowercase`, `is_ascii_alphanumeric`, `is_ascii_digit`, `is_ascii_hexdigit`, `is_ascii_punctuation`, `is_ascii_graphic`, `is_ascii_whitespace`, and `is_ascii_control` methods for `char` and `u8`.][73858] Cargo ----- - [`build-dependencies` are now built with opt-level 0 by default.][cargo/8500] You can override this by setting the following in your `Cargo.toml`. ```toml [profile.release.build-override] opt-level = 3 ``` - [`cargo-help` will now display man pages for commands rather just the `--help` text.][cargo/8456] - [`cargo-metadata` now emits a `test` field indicating if a target has tests enabled.][cargo/8478] - [`workspace.default-members` now respects `workspace.exclude`.][cargo/8485] - [`cargo-publish` will now use an alternative registry by default if it's the only registry specified in `package.publish`.][cargo/8571] Misc ---- - [Added a help button beside Rustdoc's searchbar that explains rustdoc's type based search.][75366] - [Added the Ayu theme to rustdoc.][71237] Compatibility Notes ------------------- - [Bumped the minimum supported Emscripten version to 1.39.20.][75716] - [Fixed a regression parsing `{} && false` in tail expressions.][74650] - [Added changes to how proc-macros are expanded in `macro_rules!` that should help to preserve more span information.][73084] These changes may cause compiliation errors if your macro was unhygenic or didn't correctly handle `Delimiter::None`. - [Moved support for the CloudABI target to tier 3.][75568] - [`linux-gnu` targets now require minimum kernel 2.6.32 and glibc 2.11.][74163] Internal Only -------- - [Improved default settings for bootstrapping in `x.py`.][73964] You can read details about this change in the ["Changes to `x.py` defaults"](https://blog.rust-lang.org/inside-rust/2020/08/30/changes-to-x-py-defaults.html) post on the Inside Rust blog. - [Added the `rustc-docs` component.][75560] This allows you to install and read the documentation for the compiler internal APIs. (Currently only available for `x86_64-unknown-linux-gnu`.) [1.47.0-cfg]: https://docs.microsoft.com/en-us/windows/win32/secbp/control-flow-guard [76980]: rust-lang/rust#76980 [75048]: rust-lang/rust#75048 [74163]: rust-lang/rust#74163 [71237]: rust-lang/rust#71237 [74869]: rust-lang/rust#74869 [73858]: rust-lang/rust#73858 [75716]: rust-lang/rust#75716 [75908]: rust-lang/rust#75908 [75516]: rust-lang/rust#75516 [75560]: rust-lang/rust#75560 [75568]: rust-lang/rust#75568 [75366]: rust-lang/rust#75366 [75204]: rust-lang/rust#75204 [74650]: rust-lang/rust#74650 [74419]: rust-lang/rust#74419 [73964]: rust-lang/rust#73964 [74021]: rust-lang/rust#74021 [74060]: rust-lang/rust#74060 [73893]: rust-lang/rust#73893 [73526]: rust-lang/rust#73526 [73583]: rust-lang/rust#73583 [73084]: rust-lang/rust#73084 [73197]: rust-lang/rust#73197 [72488]: rust-lang/rust#72488 [cargo/8456]: rust-lang/cargo#8456 [cargo/8478]: rust-lang/cargo#8478 [cargo/8485]: rust-lang/cargo#8485 [cargo/8500]: rust-lang/cargo#8500 [cargo/8571]: rust-lang/cargo#8571 [`Ident::new_raw`]: https://doc.rust-lang.org/nightly/proc_macro/struct.Ident.html#method.new_raw [`Range::is_empty`]: https://doc.rust-lang.org/nightly/std/ops/struct.Range.html#method.is_empty [`RangeInclusive::is_empty`]: https://doc.rust-lang.org/nightly/std/ops/struct.RangeInclusive.html#method.is_empty [`Result::as_deref_mut`]: https://doc.rust-lang.org/nightly/std/result/enum.Result.html#method.as_deref_mut [`Result::as_deref`]: https://doc.rust-lang.org/nightly/std/result/enum.Result.html#method.as_deref [`TypeId::of`]: https://doc.rust-lang.org/nightly/std/any/struct.TypeId.html#method.of [`Vec::leak`]: https://doc.rust-lang.org/nightly/std/vec/struct.Vec.html#method.leak [`f32::TAU`]: https://doc.rust-lang.org/nightly/std/f32/consts/constant.TAU.html [`f64::TAU`]: https://doc.rust-lang.org/nightly/std/f64/consts/constant.TAU.html [`pointer::offset_from`]: https://doc.rust-lang.org/nightly/std/primitive.pointer.html#method.offset_from

rust-highfive assigned ecstatic-morse Jul 28, 2020

rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Jul 28, 2020

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 Jul 29, 2020

Manishearth mentioned this pull request Jul 29, 2020

Rollup of 10 pull requests #74929

Merged

bors merged commit 4230f96 into rust-lang:master Jul 30, 2020

tmiasko deleted the must-use-closures branch July 30, 2020 02:13

tmiasko mentioned this pull request Aug 30, 2020

Update RELEASES.md for 1.47.0 #76101

Merged

ecstatic-morse mentioned this pull request Sep 24, 2020

Lint for unused borrows as part of UNUSED_MUST_USE #76894

Closed

cuviper added this to the 1.47.0 milestone May 2, 2024

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Make closures and generators a must use types #74869

Make closures and generators a must use types #74869

tmiasko commented Jul 28, 2020

rust-highfive commented Jul 28, 2020

ecstatic-morse commented Jul 29, 2020

bors commented Jul 29, 2020

ecstatic-morse commented Jul 29, 2020

rphmeier commented Jul 30, 2020

Make closures and generators a must use types #74869

Make closures and generators a must use types #74869

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tmiasko commented Jul 28, 2020

rust-highfive commented Jul 28, 2020

ecstatic-morse commented Jul 29, 2020

bors commented Jul 29, 2020

ecstatic-morse commented Jul 29, 2020

rphmeier commented Jul 30, 2020