add lint for checking unnecessary iter().any()

Author: lapla-cogito

CHANGELOG.md

@@ -6116,6 +6116,7 @@ Released 2018-09-13
 [`unnecessary_first_then_check`]: https://rust-lang.github.io/rust-clippy/master/index.html#unnecessary_first_then_check
 [`unnecessary_fold`]: https://rust-lang.github.io/rust-clippy/master/index.html#unnecessary_fold
 [`unnecessary_get_then_check`]: https://rust-lang.github.io/rust-clippy/master/index.html#unnecessary_get_then_check
+[`unnecessary_iter_any`]: https://rust-lang.github.io/rust-clippy/master/index.html#unnecessary_iter_any
 [`unnecessary_join`]: https://rust-lang.github.io/rust-clippy/master/index.html#unnecessary_join
 [`unnecessary_lazy_evaluations`]: https://rust-lang.github.io/rust-clippy/master/index.html#unnecessary_lazy_evaluations
 [`unnecessary_literal_bound`]: https://rust-lang.github.io/rust-clippy/master/index.html#unnecessary_literal_bound

clippy_lints/src/declared_lints.rs

@@ -483,6 +483,7 @@ pub static LINTS: &[&crate::LintInfo] = &[
     crate::methods::UNNECESSARY_FIRST_THEN_CHECK_INFO,
     crate::methods::UNNECESSARY_FOLD_INFO,
     crate::methods::UNNECESSARY_GET_THEN_CHECK_INFO,
+    crate::methods::UNNECESSARY_ITER_ANY_INFO,
     crate::methods::UNNECESSARY_JOIN_INFO,
     crate::methods::UNNECESSARY_LAZY_EVALUATIONS_INFO,
     crate::methods::UNNECESSARY_LITERAL_UNWRAP_INFO,

clippy_lints/src/methods/iter_any.rs

@@ -0,0 +1,51 @@
+use clippy_utils::diagnostics::span_lint;
+use rustc_hir::{Expr, ExprKind};
+use rustc_lint::LateContext;
+use rustc_middle::ty::{self};
+
+use super::{SLICE_ITER_ANY, UNNECESSARY_ITER_ANY, method_call};
+
+pub(super) fn check(cx: &LateContext<'_>, expr: &Expr<'_>) {
+    if !expr.span.from_expansion()
+    // any()
+    && let Some((name, recv, args, _, _)) = method_call(expr)
+    && name == "any"
+    // check if the inner closure is a equality check
+    && args.len() == 1
+    && let ExprKind::Closure(closure) = args[0].kind
+    && let body = cx.tcx.hir().body(closure.body)
+    && let ExprKind::Binary(op, _, _) = body.value.kind
+    && op.node == rustc_ast::ast::BinOpKind::Eq
+    // iter()
+    && let Some((name, recv, _, _, _)) = method_call(recv)
+    && name == "iter"
+    {
+        let ref_type = cx.typeck_results().expr_ty(recv);
+
+        match ref_type.kind() {
+            ty::Ref(_, inner_type, _) if inner_type.is_slice() => {
+                // check if the receiver is a u8/i8 slice
+                if let ty::Slice(slice_type) = inner_type.kind()
+                    && (slice_type.to_string() == "u8" || slice_type.to_string() == "i8")
+                {
+                    span_lint(
+                        cx,
+                        SLICE_ITER_ANY,
+                        expr.span,
+                        "using `contains()` instead of `iter().any()` on u8/i8 slices is more efficient",
+                    );
+                }
+            },
+            // if it's an array that uses `iter().any()` and its closure is an equality check, suggest using
+            // `contains()` (currently only for numeric arrays because of the difficulty in determining whether
+            // `contains()` can be replaced by `contains()` for arrays of general types)
+            ty::Array(array_type, _) if array_type.is_numeric() => span_lint(
+                cx,
+                UNNECESSARY_ITER_ANY,
+                expr.span,
+                "using `contains()` instead of `iter().any()` is more readable",
+            ),
+            _ => {},
+        }
+    }
+}

clippy_lints/src/methods/mod.rs

@@ -37,6 +37,7 @@ mod inspect_for_each;
 mod into_iter_on_ref;
 mod is_digit_ascii_radix;
 mod is_empty;
+mod iter_any;
 mod iter_cloned_collect;
 mod iter_count;
 mod iter_filter;
@@ -100,7 +101,6 @@ mod single_char_add_str;
 mod single_char_insert_string;
 mod single_char_push_string;
 mod skip_while_next;
-mod slice_iter_any;
 mod stable_sort_primitive;
 mod str_split;
 mod str_splitn;
@@ -4310,6 +4310,29 @@ declare_clippy_lint! {
     "using `contains()` instead of `iter().any()` on `u8`/`i8` slices is more fast"
 }
 
+declare_clippy_lint! {
+    /// ### What it does
+    /// Checks for usage of `iter().any()` when it can be replaced with `contains()` and suggests doing so.
+    ///
+    /// ### Why is this bad?
+    /// It makes the code less readable.
+    ///
+    /// ### Example
+    /// ```no_run
+    /// let values = &[1, 2, 3];
+    /// let _ = values.iter().any(|&v| v == 2);
+    /// ```
+    /// Use instead:
+    /// ```no_run
+    /// let values = &[1, 2, 3];
+    /// let _ = values.contains(&2);
+    /// ```
+    #[clippy::version = "1.85.0"]
+    pub UNNECESSARY_ITER_ANY,
+    style,
+    "using `contains()` instead of `iter().any()` is more readable"
+}
+
 pub struct Methods {
     avoid_breaking_exported_api: bool,
     msrv: Msrv,
@@ -4476,6 +4499,7 @@ impl_lint_pass!(Methods => [
     MAP_WITH_UNUSED_ARGUMENT_OVER_RANGES,
     UNNECESSARY_MAP_OR,
     SLICE_ITER_ANY,
+    UNNECESSARY_ITER_ANY,
 ]);
 
 /// Extracts a method call name, args, and `Span` of the method name.
@@ -4710,7 +4734,7 @@ impl Methods {
                 ("any", [arg]) => {
                     unused_enumerate_index::check(cx, expr, recv, arg);
                     needless_character_iteration::check(cx, expr, recv, arg, false);
-                    slice_iter_any::check(cx, expr);
+                    iter_any::check(cx, expr);
                     match method_call(recv) {
                         Some(("cloned", recv2, [], _, _)) => iter_overeager_cloned::check(
                             cx,

clippy_lints/src/methods/slice_iter_any.rs

@@ -18,7 +18,7 @@ fn main() {
 
     let values: [u8; 6] = [3, 14, 15, 92, 6, 5];
     let _ = values.iter().any(|&v| v == 10);
-    // no error, because it's an array
+    //~^ ERROR: using `contains()` instead of `iter().any()` is more readable
 
     let values: [u8; 6] = [3, 14, 15, 92, 6, 5];
     let _ = values.iter().any(|&v| v > 10);
@@ -32,5 +32,5 @@ fn foo(values: &[u8]) -> bool {
 
 fn bar(values: [u8; 3]) -> bool {
     values.iter().any(|&v| v == 10)
-    // no error, because it's an array
+    //~^ ERROR: using `contains()` instead of `iter().any()` is more readable
 }

tests/ui/slice_iter_any.rs renamed to tests/ui/iter_any.rs

@@ -0,0 +1,32 @@
+error: using `contains()` instead of `iter().any()` on u8/i8 slices is more efficient
+  --> tests/ui/iter_any.rs:6:13
+   |
+LL |     let _ = values.iter().any(|&v| v == 4);
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: `-D clippy::slice-iter-any` implied by `-D warnings`
+   = help: to override `-D warnings` add `#[allow(clippy::slice_iter_any)]`
+
+error: using `contains()` instead of `iter().any()` is more readable
+  --> tests/ui/iter_any.rs:20:13
+   |
+LL |     let _ = values.iter().any(|&v| v == 10);
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: `-D clippy::unnecessary-iter-any` implied by `-D warnings`
+   = help: to override `-D warnings` add `#[allow(clippy::unnecessary_iter_any)]`
+
+error: using `contains()` instead of `iter().any()` on u8/i8 slices is more efficient
+  --> tests/ui/iter_any.rs:29:5
+   |
+LL |     values.iter().any(|&v| v == 10)
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: using `contains()` instead of `iter().any()` is more readable
+  --> tests/ui/iter_any.rs:34:5
+   |
+LL |     values.iter().any(|&v| v == 10)
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 4 previous errors
+

tests/ui/iter_any.stderr

@@ -3,7 +3,12 @@
 use std::collections::{BTreeMap, BTreeSet, BinaryHeap, HashMap, HashSet, LinkedList};
 
 #[warn(clippy::needless_collect)]
-#[allow(unused_variables, clippy::iter_cloned_collect, clippy::iter_next_slice)]
+#[allow(
+    unused_variables,
+    clippy::unnecessary_iter_any,
+    clippy::iter_cloned_collect,
+    clippy::iter_next_slice
+)]
 fn main() {
     let sample = [1; 5];
     let len = sample.iter().count();

tests/ui/needless_collect.fixed

@@ -3,7 +3,12 @@
 use std::collections::{BTreeMap, BTreeSet, BinaryHeap, HashMap, HashSet, LinkedList};
 
 #[warn(clippy::needless_collect)]
-#[allow(unused_variables, clippy::iter_cloned_collect, clippy::iter_next_slice)]
+#[allow(
+    unused_variables,
+    clippy::unnecessary_iter_any,
+    clippy::iter_cloned_collect,
+    clippy::iter_next_slice
+)]
 fn main() {
     let sample = [1; 5];
     let len = sample.iter().collect::<Vec<_>>().len();

tests/ui/needless_collect.rs

@@ -1,5 +1,5 @@
 error: avoid using `collect()` when not needed
-  --> tests/ui/needless_collect.rs:9:29
+  --> tests/ui/needless_collect.rs:14:29
    |
 LL |     let len = sample.iter().collect::<Vec<_>>().len();
    |                             ^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace with: `count()`
@@ -8,109 +8,109 @@ LL |     let len = sample.iter().collect::<Vec<_>>().len();
    = help: to override `-D warnings` add `#[allow(clippy::needless_collect)]`
 
 error: avoid using `collect()` when not needed
-  --> tests/ui/needless_collect.rs:10:22
+  --> tests/ui/needless_collect.rs:15:22
    |
 LL |     if sample.iter().collect::<Vec<_>>().is_empty() {
    |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace with: `next().is_none()`
 
 error: avoid using `collect()` when not needed
-  --> tests/ui/needless_collect.rs:13:28
+  --> tests/ui/needless_collect.rs:18:28
    |
 LL |     sample.iter().cloned().collect::<Vec<_>>().contains(&1);
    |                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace with: `any(|x| x == 1)`
 
 error: avoid using `collect()` when not needed
-  --> tests/ui/needless_collect.rs:18:35
+  --> tests/ui/needless_collect.rs:23:35
    |
 LL |     sample.iter().map(|x| (x, x)).collect::<HashMap<_, _>>().is_empty();
    |                                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace with: `next().is_none()`
 
 error: avoid using `collect()` when not needed
-  --> tests/ui/needless_collect.rs:19:35
+  --> tests/ui/needless_collect.rs:24:35
    |
 LL |     sample.iter().map(|x| (x, x)).collect::<BTreeMap<_, _>>().is_empty();
    |                                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace with: `next().is_none()`
 
 error: avoid using `collect()` when not needed
-  --> tests/ui/needless_collect.rs:26:19
+  --> tests/ui/needless_collect.rs:31:19
    |
 LL |     sample.iter().collect::<LinkedList<_>>().len();
    |                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace with: `count()`
 
 error: avoid using `collect()` when not needed
-  --> tests/ui/needless_collect.rs:27:19
+  --> tests/ui/needless_collect.rs:32:19
    |
 LL |     sample.iter().collect::<LinkedList<_>>().is_empty();
    |                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace with: `next().is_none()`
 
 error: avoid using `collect()` when not needed
-  --> tests/ui/needless_collect.rs:28:28
+  --> tests/ui/needless_collect.rs:33:28
    |
 LL |     sample.iter().cloned().collect::<LinkedList<_>>().contains(&1);
    |                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace with: `any(|x| x == 1)`
 
 error: avoid using `collect()` when not needed
-  --> tests/ui/needless_collect.rs:29:19
+  --> tests/ui/needless_collect.rs:34:19
    |
 LL |     sample.iter().collect::<LinkedList<_>>().contains(&&1);
    |                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace with: `any(|x| x == &1)`
 
 error: avoid using `collect()` when not needed
-  --> tests/ui/needless_collect.rs:32:19
+  --> tests/ui/needless_collect.rs:37:19
    |
 LL |     sample.iter().collect::<BinaryHeap<_>>().len();
    |                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace with: `count()`
 
 error: avoid using `collect()` when not needed
-  --> tests/ui/needless_collect.rs:33:19
+  --> tests/ui/needless_collect.rs:38:19
    |
 LL |     sample.iter().collect::<BinaryHeap<_>>().is_empty();
    |                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace with: `next().is_none()`
 
 error: avoid using `collect()` when not needed
-  --> tests/ui/needless_collect.rs:38:27
+  --> tests/ui/needless_collect.rs:43:27
    |
 LL |     let _ = sample.iter().collect::<HashSet<_>>().is_empty();
    |                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace with: `next().is_none()`
 
 error: avoid using `collect()` when not needed
-  --> tests/ui/needless_collect.rs:39:27
+  --> tests/ui/needless_collect.rs:44:27
    |
 LL |     let _ = sample.iter().collect::<HashSet<_>>().contains(&&0);
    |                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace with: `any(|x| x == &0)`
 
 error: avoid using `collect()` when not needed
-  --> tests/ui/needless_collect.rs:61:27
+  --> tests/ui/needless_collect.rs:66:27
    |
 LL |     let _ = sample.iter().collect::<VecWrapper<_>>().is_empty();
    |                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace with: `next().is_none()`
 
 error: avoid using `collect()` when not needed
-  --> tests/ui/needless_collect.rs:62:27
+  --> tests/ui/needless_collect.rs:67:27
    |
 LL |     let _ = sample.iter().collect::<VecWrapper<_>>().contains(&&0);
    |                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace with: `any(|x| x == &0)`
 
 error: avoid using `collect()` when not needed
-  --> tests/ui/needless_collect.rs:66:40
+  --> tests/ui/needless_collect.rs:71:40
    |
 LL |         Vec::<u8>::new().extend((0..10).collect::<Vec<_>>());
    |                                        ^^^^^^^^^^^^^^^^^^^^ help: remove this call
 
 error: avoid using `collect()` when not needed
-  --> tests/ui/needless_collect.rs:67:20
+  --> tests/ui/needless_collect.rs:72:20
    |
 LL |         foo((0..10).collect::<Vec<_>>());
    |                    ^^^^^^^^^^^^^^^^^^^^ help: remove this call
 
 error: avoid using `collect()` when not needed
-  --> tests/ui/needless_collect.rs:68:49
+  --> tests/ui/needless_collect.rs:73:49
    |
 LL |         bar((0..10).collect::<Vec<_>>(), (0..10).collect::<Vec<_>>());
    |                                                 ^^^^^^^^^^^^^^^^^^^^ help: remove this call
 
 error: avoid using `collect()` when not needed
-  --> tests/ui/needless_collect.rs:69:37
+  --> tests/ui/needless_collect.rs:74:37
    |
 LL |         baz((0..10), (), ('a'..='z').collect::<Vec<_>>())
    |                                     ^^^^^^^^^^^^^^^^^^^^ help: remove this call