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Added from_over_into lint
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8 files changed

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‎CHANGELOG.md

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@@ -1841,6 +1841,7 @@ Released 2018-09-13
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[`forget_copy`]: https://rust-lang.github.io/rust-clippy/master/index.html#forget_copy
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[`forget_ref`]: https://rust-lang.github.io/rust-clippy/master/index.html#forget_ref
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[`from_iter_instead_of_collect`]: https://rust-lang.github.io/rust-clippy/master/index.html#from_iter_instead_of_collect
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[`from_over_into`]: https://rust-lang.github.io/rust-clippy/master/index.html#from_over_into
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[`future_not_send`]: https://rust-lang.github.io/rust-clippy/master/index.html#future_not_send
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[`get_last_with_len`]: https://rust-lang.github.io/rust-clippy/master/index.html#get_last_with_len
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[`get_unwrap`]: https://rust-lang.github.io/rust-clippy/master/index.html#get_unwrap

‎clippy_lints/src/from_over_into.rs

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@@ -0,0 +1,63 @@
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use crate::utils::paths::INTO;
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use crate::utils::{match_def_path, span_lint_and_help};
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use if_chain::if_chain;
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use rustc_hir as hir;
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use rustc_lint::{LateContext, LateLintPass};
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use rustc_session::{declare_lint_pass, declare_tool_lint};
7+
8+
declare_clippy_lint! {
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/// **What it does:** Searches for implementations of the `Into<..>` trait and suggests to implement `From<..>` instead.
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///
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/// **Why is this bad?** According the std docs implementing `From<..>` is preferred since it gives you `Into<..>` for free where the reverse isn't true.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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///
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/// ```rust
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/// struct StringWrapper(String);
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///
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/// impl Into<StringWrapper> for String {
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/// fn into(self) -> StringWrapper {
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/// StringWrapper(self)
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/// }
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/// }
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/// ```
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/// Use instead:
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/// ```rust
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/// struct StringWrapper(String);
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///
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/// impl From<String> for StringWrapper {
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/// fn from(s: String) -> StringWrapper {
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/// StringWrapper(s)
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/// }
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/// }
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/// ```
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pub FROM_OVER_INTO,
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style,
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"Warns on implementations of `Into<..>` to use `From<..>`"
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}
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declare_lint_pass!(FromOverInto => [FROM_OVER_INTO]);
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impl LateLintPass<'_> for FromOverInto {
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fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx hir::Item<'_>) {
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let impl_def_id = cx.tcx.hir().local_def_id(item.hir_id);
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if_chain! {
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if let hir::ItemKind::Impl{ .. } = &item.kind;
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if let Some(impl_trait_ref) = cx.tcx.impl_trait_ref(impl_def_id);
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if match_def_path(cx, impl_trait_ref.def_id, &INTO);
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then {
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span_lint_and_help(
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cx,
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FROM_OVER_INTO,
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item.span,
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"An implementation of From is preferred since it gives you Into<..> for free where the reverse isn't true.",
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None,
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"consider implement From instead",
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);
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}
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}
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}
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}

‎clippy_lints/src/lib.rs

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@@ -207,6 +207,7 @@ mod float_literal;
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mod floating_point_arithmetic;
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mod format;
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mod formatting;
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mod from_over_into;
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mod functions;
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mod future_not_send;
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mod get_last_with_len;
@@ -614,6 +615,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
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&formatting::SUSPICIOUS_ASSIGNMENT_FORMATTING,
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&formatting::SUSPICIOUS_ELSE_FORMATTING,
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&formatting::SUSPICIOUS_UNARY_OP_FORMATTING,
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&from_over_into::FROM_OVER_INTO,
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&functions::DOUBLE_MUST_USE,
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&functions::MUST_USE_CANDIDATE,
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&functions::MUST_USE_UNIT,
@@ -1203,6 +1205,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
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store.register_late_pass(|| box manual_unwrap_or::ManualUnwrapOr);
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store.register_late_pass(|| box manual_ok_or::ManualOkOr);
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store.register_late_pass(|| box float_equality_without_abs::FloatEqualityWithoutAbs);
1208+
store.register_late_pass(|| box from_over_into::FromOverInto);
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store.register_late_pass(|| box async_yields_async::AsyncYieldsAsync);
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let disallowed_methods = conf.disallowed_methods.iter().cloned().collect::<FxHashSet<_>>();
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store.register_late_pass(move || box disallowed_method::DisallowedMethod::new(&disallowed_methods));
@@ -1417,6 +1420,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
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LintId::of(&formatting::SUSPICIOUS_ASSIGNMENT_FORMATTING),
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LintId::of(&formatting::SUSPICIOUS_ELSE_FORMATTING),
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LintId::of(&formatting::SUSPICIOUS_UNARY_OP_FORMATTING),
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LintId::of(&from_over_into::FROM_OVER_INTO),
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LintId::of(&functions::DOUBLE_MUST_USE),
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LintId::of(&functions::MUST_USE_UNIT),
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LintId::of(&functions::NOT_UNSAFE_PTR_ARG_DEREF),
@@ -1663,6 +1667,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
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LintId::of(&formatting::SUSPICIOUS_ASSIGNMENT_FORMATTING),
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LintId::of(&formatting::SUSPICIOUS_ELSE_FORMATTING),
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LintId::of(&formatting::SUSPICIOUS_UNARY_OP_FORMATTING),
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LintId::of(&from_over_into::FROM_OVER_INTO),
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LintId::of(&functions::DOUBLE_MUST_USE),
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LintId::of(&functions::MUST_USE_UNIT),
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LintId::of(&functions::RESULT_UNIT_ERR),

‎tests/ui/from_over_into.rs

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@@ -0,0 +1,21 @@
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#![warn(clippy::from_over_into)]
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// this should throw an error
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struct StringWrapper(String);
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impl Into<StringWrapper> for String {
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fn into(self) -> StringWrapper {
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StringWrapper(self)
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}
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}
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// this is fine
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struct A(String);
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impl From<String> for A {
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fn from(s: String) -> A {
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A(s)
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}
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}
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fn main() {}

‎tests/ui/from_over_into.stderr

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error: An implementation of From is preferred since it gives you Into<..> for free where the reverse isn't true.
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--> $DIR/from_over_into.rs:6:1
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|
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LL | / impl Into<StringWrapper> for String {
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LL | | fn into(self) -> StringWrapper {
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LL | | StringWrapper(self)
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LL | | }
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LL | | }
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| |_^
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|
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= note: `-D clippy::from-over-into` implied by `-D warnings`
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= help: consider implement From instead
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error: aborting due to previous error
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‎tests/ui/unused_unit.fixed

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@@ -11,6 +11,7 @@
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#![deny(clippy::unused_unit)]
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#![allow(dead_code)]
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#![allow(clippy::from_over_into)]
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struct Unitter;
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impl Unitter {

‎tests/ui/unused_unit.rs

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@@ -11,6 +11,7 @@
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#![deny(clippy::unused_unit)]
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#![allow(dead_code)]
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#![allow(clippy::from_over_into)]
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struct Unitter;
1617
impl Unitter {

‎tests/ui/unused_unit.stderr

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@@ -1,5 +1,5 @@
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error: unneeded unit return type
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--> $DIR/unused_unit.rs:18:28
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--> $DIR/unused_unit.rs:19:28
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|
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LL | pub fn get_unit<F: Fn() -> (), G>(&self, f: F, _g: G) -> ()
55
| ^^^^^^ help: remove the `-> ()`
@@ -11,109 +11,109 @@ LL | #![deny(clippy::unused_unit)]
1111
| ^^^^^^^^^^^^^^^^^^^
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1313
error: unneeded unit return type
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--> $DIR/unused_unit.rs:19:18
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--> $DIR/unused_unit.rs:20:18
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|
1616
LL | where G: Fn() -> () {
1717
| ^^^^^^ help: remove the `-> ()`
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1919
error: unneeded unit return type
20-
--> $DIR/unused_unit.rs:18:58
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--> $DIR/unused_unit.rs:19:58
2121
|
2222
LL | pub fn get_unit<F: Fn() -> (), G>(&self, f: F, _g: G) -> ()
2323
| ^^^^^^ help: remove the `-> ()`
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2525
error: unneeded unit return type
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--> $DIR/unused_unit.rs:20:26
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--> $DIR/unused_unit.rs:21:26
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|
2828
LL | let _y: &dyn Fn() -> () = &f;
2929
| ^^^^^^ help: remove the `-> ()`
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3131
error: unneeded unit return type
32-
--> $DIR/unused_unit.rs:27:18
32+
--> $DIR/unused_unit.rs:28:18
3333
|
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LL | fn into(self) -> () {
3535
| ^^^^^^ help: remove the `-> ()`
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3737
error: unneeded unit expression
38-
--> $DIR/unused_unit.rs:28:9
38+
--> $DIR/unused_unit.rs:29:9
3939
|
4040
LL | ()
4141
| ^^ help: remove the final `()`
4242

4343
error: unneeded unit return type
44-
--> $DIR/unused_unit.rs:33:29
44+
--> $DIR/unused_unit.rs:34:29
4545
|
4646
LL | fn redundant<F: FnOnce() -> (), G, H>(&self, _f: F, _g: G, _h: H)
4747
| ^^^^^^ help: remove the `-> ()`
4848

4949
error: unneeded unit return type
50-
--> $DIR/unused_unit.rs:35:19
50+
--> $DIR/unused_unit.rs:36:19
5151
|
5252
LL | G: FnMut() -> (),
5353
| ^^^^^^ help: remove the `-> ()`
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5555
error: unneeded unit return type
56-
--> $DIR/unused_unit.rs:36:16
56+
--> $DIR/unused_unit.rs:37:16
5757
|
5858
LL | H: Fn() -> ();
5959
| ^^^^^^ help: remove the `-> ()`
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6161
error: unneeded unit return type
62-
--> $DIR/unused_unit.rs:40:29
62+
--> $DIR/unused_unit.rs:41:29
6363
|
6464
LL | fn redundant<F: FnOnce() -> (), G, H>(&self, _f: F, _g: G, _h: H)
6565
| ^^^^^^ help: remove the `-> ()`
6666

6767
error: unneeded unit return type
68-
--> $DIR/unused_unit.rs:42:19
68+
--> $DIR/unused_unit.rs:43:19
6969
|
7070
LL | G: FnMut() -> (),
7171
| ^^^^^^ help: remove the `-> ()`
7272

7373
error: unneeded unit return type
74-
--> $DIR/unused_unit.rs:43:16
74+
--> $DIR/unused_unit.rs:44:16
7575
|
7676
LL | H: Fn() -> () {}
7777
| ^^^^^^ help: remove the `-> ()`
7878

7979
error: unneeded unit return type
80-
--> $DIR/unused_unit.rs:46:17
80+
--> $DIR/unused_unit.rs:47:17
8181
|
8282
LL | fn return_unit() -> () { () }
8383
| ^^^^^^ help: remove the `-> ()`
8484

8585
error: unneeded unit expression
86-
--> $DIR/unused_unit.rs:46:26
86+
--> $DIR/unused_unit.rs:47:26
8787
|
8888
LL | fn return_unit() -> () { () }
8989
| ^^ help: remove the final `()`
9090

9191
error: unneeded `()`
92-
--> $DIR/unused_unit.rs:56:14
92+
--> $DIR/unused_unit.rs:57:14
9393
|
9494
LL | break();
9595
| ^^ help: remove the `()`
9696

9797
error: unneeded `()`
98-
--> $DIR/unused_unit.rs:58:11
98+
--> $DIR/unused_unit.rs:59:11
9999
|
100100
LL | return();
101101
| ^^ help: remove the `()`
102102

103103
error: unneeded unit return type
104-
--> $DIR/unused_unit.rs:75:10
104+
--> $DIR/unused_unit.rs:76:10
105105
|
106106
LL | fn test()->(){}
107107
| ^^^^ help: remove the `-> ()`
108108

109109
error: unneeded unit return type
110-
--> $DIR/unused_unit.rs:78:11
110+
--> $DIR/unused_unit.rs:79:11
111111
|
112112
LL | fn test2() ->(){}
113113
| ^^^^^ help: remove the `-> ()`
114114

115115
error: unneeded unit return type
116-
--> $DIR/unused_unit.rs:81:11
116+
--> $DIR/unused_unit.rs:82:11
117117
|
118118
LL | fn test3()-> (){}
119119
| ^^^^^ help: remove the `-> ()`

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