Split redundant_closure lint

CHANGELOG.md

@@ -1035,6 +1035,7 @@ All notable changes to this project will be documented in this file.
 [`redundant_clone`]: https://rust-lang.github.io/rust-clippy/master/index.html#redundant_clone
 [`redundant_closure`]: https://rust-lang.github.io/rust-clippy/master/index.html#redundant_closure
 [`redundant_closure_call`]: https://rust-lang.github.io/rust-clippy/master/index.html#redundant_closure_call
+[`redundant_closure_for_method_calls`]: https://rust-lang.github.io/rust-clippy/master/index.html#redundant_closure_for_method_calls
 [`redundant_field_names`]: https://rust-lang.github.io/rust-clippy/master/index.html#redundant_field_names
 [`redundant_pattern`]: https://rust-lang.github.io/rust-clippy/master/index.html#redundant_pattern
 [`redundant_pattern_matching`]: https://rust-lang.github.io/rust-clippy/master/index.html#redundant_pattern_matching

README.md

@@ -7,7 +7,7 @@
 
 A collection of lints to catch common mistakes and improve your [Rust](https://github.com/rust-lang/rust) code.
 
-[There are 301 lints included in this crate!](https://rust-lang.github.io/rust-clippy/master/index.html)
+[There are 302 lints included in this crate!](https://rust-lang.github.io/rust-clippy/master/index.html)
 
 We have a bunch of lint categories to allow you to choose how much Clippy is supposed to ~~annoy~~ help you:
 

clippy_lints/src/eta_reduction.rs

@@ -32,7 +32,30 @@ declare_clippy_lint! {
  "redundant closures, i.e., `|a| foo(a)` (which can be written as just `foo`)"
 }
 
-declare_lint_pass!(EtaReduction => [REDUNDANT_CLOSURE]);
+declare_clippy_lint! {
+ /// **What it does:** Checks for closures which only invoke a method on the closure
+ /// argument and can be replaced by referencing the method directly.
+ ///
+ /// **Why is this bad?** It's unnecessary to create the closure.
+ ///
+ /// **Known problems:** rust-lang/rust-clippy#3071, rust-lang/rust-clippy#4002,
+ /// rust-lang/rust-clippy#3942
+ ///
+ ///
+ /// **Example:**
+ /// ```rust,ignore
+ /// Some('a').map(|s| s.to_uppercase());
+ /// ```
+ /// may be rewritten as
+ /// ```rust,ignore
+ /// Some('a').map(char::to_uppercase);
+ /// ```
+ pub REDUNDANT_CLOSURE_FOR_METHOD_CALLS,
+ pedantic,
+ "redundant closures for method calls"
+}
+
+declare_lint_pass!(EtaReduction => [REDUNDANT_CLOSURE, REDUNDANT_CLOSURE_FOR_METHOD_CALLS]);
 
 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for EtaReduction {
  fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
@@ -104,7 +127,7 @@ fn check_closure(cx: &LateContext<'_, '_>, expr: &Expr) {
  if let Some(name) = get_ufcs_type_name(cx, method_def_id, &args[0]);
 
  then {
- span_lint_and_then(cx, REDUNDANT_CLOSURE, expr.span, "redundant closure found", |db| {
+ span_lint_and_then(cx, REDUNDANT_CLOSURE_FOR_METHOD_CALLS, expr.span, "redundant closure found", |db| {
  db.span_suggestion(
  expr.span,
  "remove closure as shown",

clippy_lints/src/lib.rs

@@ -614,6 +614,7 @@ pub fn register_plugins(reg: &mut rustc_plugin::Registry<'_>, conf: &Conf) {
  enum_glob_use::ENUM_GLOB_USE,
  enum_variants::MODULE_NAME_REPETITIONS,
  enum_variants::PUB_ENUM_VARIANT_NAMES,
+ eta_reduction::REDUNDANT_CLOSURE_FOR_METHOD_CALLS,
  functions::TOO_MANY_LINES,
  if_not_else::IF_NOT_ELSE,
  infinite_iter::MAYBE_INFINITE_ITER,

tests/ui/eta.fixed

@@ -9,7 +9,11 @@
  clippy::option_map_unit_fn,
  clippy::trivially_copy_pass_by_ref
 )]
-#![warn(clippy::redundant_closure, clippy::needless_borrow)]
+#![warn(
+ clippy::redundant_closure,
+ clippy::redundant_closure_for_method_calls,
+ clippy::needless_borrow
+)]
 
 use std::path::PathBuf;
 

tests/ui/eta.rs

@@ -9,7 +9,11 @@
  clippy::option_map_unit_fn,
  clippy::trivially_copy_pass_by_ref
 )]
-#![warn(clippy::redundant_closure, clippy::needless_borrow)]
+#![warn(
+ clippy::redundant_closure,
+ clippy::redundant_closure_for_method_calls,
+ clippy::needless_borrow
+)]
 
 use std::path::PathBuf;
 

tests/ui/eta.stderr

@@ -1,87 +1,89 @@
 error: redundant closure found
- --> $DIR/eta.rs:17:27
+ --> $DIR/eta.rs:21:27
  |
 LL | let a = Some(1u8).map(|a| foo(a));
  | ^^^^^^^^^^ help: remove closure as shown: `foo`
  |
  = note: `-D clippy::redundant-closure` implied by `-D warnings`
 
 error: redundant closure found
- --> $DIR/eta.rs:18:10
+ --> $DIR/eta.rs:22:10
  |
 LL | meta(|a| foo(a));
  | ^^^^^^^^^^ help: remove closure as shown: `foo`
 
 error: redundant closure found
- --> $DIR/eta.rs:19:27
+ --> $DIR/eta.rs:23:27
  |
 LL | let c = Some(1u8).map(|a| {1+2; foo}(a));
  | ^^^^^^^^^^^^^^^^^ help: remove closure as shown: `{1+2; foo}`
 
 error: this expression borrows a reference that is immediately dereferenced by the compiler
- --> $DIR/eta.rs:21:21
+ --> $DIR/eta.rs:25:21
  |
 LL | all(&[1, 2, 3], &&2, |x, y| below(x, y)); //is adjusted
  | ^^^ help: change this to: `&2`
  |
  = note: `-D clippy::needless-borrow` implied by `-D warnings`
 
 error: redundant closure found
- --> $DIR/eta.rs:28:27
+ --> $DIR/eta.rs:32:27
  |
 LL | let e = Some(1u8).map(|a| generic(a));
  | ^^^^^^^^^^^^^^ help: remove closure as shown: `generic`
 
 error: redundant closure found
- --> $DIR/eta.rs:71:51
+ --> $DIR/eta.rs:75:51
  |
 LL | let e = Some(TestStruct { some_ref: &i }).map(|a| a.foo());
  | ^^^^^^^^^^^ help: remove closure as shown: `TestStruct::foo`
+ |
+ = note: `-D clippy::redundant-closure-for-method-calls` implied by `-D warnings`
 
 error: redundant closure found
- --> $DIR/eta.rs:73:51
+ --> $DIR/eta.rs:77:51
  |
 LL | let e = Some(TestStruct { some_ref: &i }).map(|a| a.trait_foo());
  | ^^^^^^^^^^^^^^^^^ help: remove closure as shown: `TestTrait::trait_foo`
 
 error: redundant closure found
- --> $DIR/eta.rs:76:42
+ --> $DIR/eta.rs:80:42
  |
 LL | let e = Some(&mut vec![1, 2, 3]).map(|v| v.clear());
  | ^^^^^^^^^^^^^ help: remove closure as shown: `std::vec::Vec::clear`
 
 error: redundant closure found
- --> $DIR/eta.rs:81:29
+ --> $DIR/eta.rs:85:29
  |
 LL | let e = Some("str").map(|s| s.to_string());
  | ^^^^^^^^^^^^^^^^^ help: remove closure as shown: `std::string::ToString::to_string`
 
 error: redundant closure found
- --> $DIR/eta.rs:83:27
+ --> $DIR/eta.rs:87:27
  |
 LL | let e = Some('a').map(|s| s.to_uppercase());
  | ^^^^^^^^^^^^^^^^^^^^ help: remove closure as shown: `char::to_uppercase`
 
 error: redundant closure found
- --> $DIR/eta.rs:86:65
+ --> $DIR/eta.rs:90:65
  |
 LL | let e: std::vec::Vec<char> = vec!['a', 'b', 'c'].iter().map(|c| c.to_ascii_uppercase()).collect();
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: remove closure as shown: `char::to_ascii_uppercase`
 
 error: redundant closure found
- --> $DIR/eta.rs:104:50
+ --> $DIR/eta.rs:108:50
  |
 LL | let _: Vec<_> = arr.iter().map(|x| x.map_err(|e| some.take().unwrap()(e))).collect();
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: remove closure as shown: `some.take().unwrap()`
 
 error: redundant closure found
- --> $DIR/eta.rs:169:27
+ --> $DIR/eta.rs:173:27
  |
 LL | let a = Some(1u8).map(|a| foo_ptr(a));
  | ^^^^^^^^^^^^^^ help: remove closure as shown: `foo_ptr`
 
 error: redundant closure found
- --> $DIR/eta.rs:174:27
+ --> $DIR/eta.rs:178:27
  |
 LL | let a = Some(1u8).map(|a| closure(a));
  | ^^^^^^^^^^^^^^ help: remove closure as shown: `closure`

tests/ui/map_clone.fixed

@@ -3,7 +3,7 @@
 #![allow(clippy::iter_cloned_collect)]
 #![allow(clippy::clone_on_copy)]
 #![allow(clippy::missing_docs_in_private_items)]
-#![allow(clippy::redundant_closure)]
+#![allow(clippy::redundant_closure_for_method_calls)]
 
 fn main() {
  let _: Vec<i8> = vec![5_i8; 6].iter().copied().collect();

tests/ui/map_clone.rs

@@ -3,7 +3,7 @@
 #![allow(clippy::iter_cloned_collect)]
 #![allow(clippy::clone_on_copy)]
 #![allow(clippy::missing_docs_in_private_items)]
-#![allow(clippy::redundant_closure)]
+#![allow(clippy::redundant_closure_for_method_calls)]
 
 fn main() {
  let _: Vec<i8> = vec![5_i8; 6].iter().map(|x| *x).collect();