diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7188e6f9324..397916fe409 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -896,7 +896,9 @@ All notable changes to this project will be documented in this file.
[`extra_unused_lifetimes`]: https://rust-lang.github.io/rust-clippy/master/index.html#extra_unused_lifetimes
[`fallible_impl_from`]: https://rust-lang.github.io/rust-clippy/master/index.html#fallible_impl_from
[`filter_map`]: https://rust-lang.github.io/rust-clippy/master/index.html#filter_map
+[`filter_map_next`]: https://rust-lang.github.io/rust-clippy/master/index.html#filter_map_next
[`filter_next`]: https://rust-lang.github.io/rust-clippy/master/index.html#filter_next
+[`find_map`]: https://rust-lang.github.io/rust-clippy/master/index.html#find_map
[`float_arithmetic`]: https://rust-lang.github.io/rust-clippy/master/index.html#float_arithmetic
[`float_cmp`]: https://rust-lang.github.io/rust-clippy/master/index.html#float_cmp
[`float_cmp_const`]: https://rust-lang.github.io/rust-clippy/master/index.html#float_cmp_const
diff --git a/README.md b/README.md
index 9ca5761a2ba..4ed388db176 100644
--- a/README.md
+++ b/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 299 lints included in this crate!](https://rust-lang.github.io/rust-clippy/master/index.html)
+[There are 301 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:
diff --git a/clippy_lints/src/lib.rs b/clippy_lints/src/lib.rs
index 4220e6a738b..0f09f678e4b 100644
--- a/clippy_lints/src/lib.rs
+++ b/clippy_lints/src/lib.rs
@@ -622,6 +622,8 @@ pub fn register_plugins(reg: &mut rustc_plugin::Registry<'_>, conf: &Conf) {
loops::EXPLICIT_ITER_LOOP,
matches::SINGLE_MATCH_ELSE,
methods::FILTER_MAP,
+ methods::FILTER_MAP_NEXT,
+ methods::FIND_MAP,
methods::MAP_FLATTEN,
methods::OPTION_MAP_UNWRAP_OR,
methods::OPTION_MAP_UNWRAP_OR_ELSE,
diff --git a/clippy_lints/src/methods/mod.rs b/clippy_lints/src/methods/mod.rs
index d8595ea9004..2904fd4c98d 100644
--- a/clippy_lints/src/methods/mod.rs
+++ b/clippy_lints/src/methods/mod.rs
@@ -288,6 +288,50 @@ declare_clippy_lint! {
"using combinations of `filter`, `map`, `filter_map` and `flat_map` which can usually be written as a single method call"
}
+declare_clippy_lint! {
+ /// **What it does:** Checks for usage of `_.filter_map(_).next()`.
+ ///
+ /// **Why is this bad?** Readability, this can be written more concisely as a
+ /// single method call.
+ ///
+ /// **Known problems:** None
+ ///
+ /// **Example:**
+ /// ```rust
+ /// (0..3).filter_map(|x| if x == 2 { Some(x) } else { None }).next();
+ /// ```
+ /// Can be written as
+ ///
+ /// ```rust
+ /// (0..3).find_map(|x| if x == 2 { Some(x) } else { None });
+ /// ```
+ pub FILTER_MAP_NEXT,
+ pedantic,
+ "using combination of `filter_map` and `next` which can usually be written as a single method call"
+}
+
+declare_clippy_lint! {
+ /// **What it does:** Checks for usage of `_.find(_).map(_)`.
+ ///
+ /// **Why is this bad?** Readability, this can be written more concisely as a
+ /// single method call.
+ ///
+ /// **Known problems:** Often requires a condition + Option/Iterator creation
+ /// inside the closure.
+ ///
+ /// **Example:**
+ /// ```rust
+ /// (0..3).find(|x| x == 2).map(|x| x * 2);
+ /// ```
+ /// Can be written as
+ /// ```rust
+ /// (0..3).find_map(|x| if x == 2 { Some(x * 2) } else { None });
+ /// ```
+ pub FIND_MAP,
+ pedantic,
+ "using a combination of `find` and `map` can usually be written as a single method call"
+}
+
declare_clippy_lint! {
/// **What it does:** Checks for an iterator search (such as `find()`,
/// `position()`, or `rposition()`) followed by a call to `is_some()`.
@@ -798,6 +842,8 @@ declare_lint_pass!(Methods => [
TEMPORARY_CSTRING_AS_PTR,
FILTER_NEXT,
FILTER_MAP,
+ FILTER_MAP_NEXT,
+ FIND_MAP,
MAP_FLATTEN,
ITER_NTH,
ITER_SKIP_NEXT,
@@ -833,6 +879,8 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Methods {
["next", "filter"] => lint_filter_next(cx, expr, arg_lists[1]),
["map", "filter"] => lint_filter_map(cx, expr, arg_lists[1], arg_lists[0]),
["map", "filter_map"] => lint_filter_map_map(cx, expr, arg_lists[1], arg_lists[0]),
+ ["next", "filter_map"] => lint_filter_map_next(cx, expr, arg_lists[1]),
+ ["map", "find"] => lint_find_map(cx, expr, arg_lists[1], arg_lists[0]),
["flat_map", "filter"] => lint_filter_flat_map(cx, expr, arg_lists[1], arg_lists[0]),
["flat_map", "filter_map"] => lint_filter_map_flat_map(cx, expr, arg_lists[1], arg_lists[0]),
["flatten", "map"] => lint_map_flatten(cx, expr, arg_lists[1]),
@@ -1911,6 +1959,42 @@ fn lint_filter_map<'a, 'tcx>(
}
}
+/// lint use of `filter_map().next()` for `Iterators`
+fn lint_filter_map_next<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &'tcx hir::Expr, filter_args: &'tcx [hir::Expr]) {
+ if match_trait_method(cx, expr, &paths::ITERATOR) {
+ let msg = "called `filter_map(p).next()` on an `Iterator`. This is more succinctly expressed by calling \
+ `.find_map(p)` instead.";
+ let filter_snippet = snippet(cx, filter_args[1].span, "..");
+ if filter_snippet.lines().count() <= 1 {
+ span_note_and_lint(
+ cx,
+ FILTER_MAP_NEXT,
+ expr.span,
+ msg,
+ expr.span,
+ &format!("replace `filter_map({0}).next()` with `find_map({0})`", filter_snippet),
+ );
+ } else {
+ span_lint(cx, FILTER_MAP_NEXT, expr.span, msg);
+ }
+ }
+}
+
+/// lint use of `find().map()` for `Iterators`
+fn lint_find_map<'a, 'tcx>(
+ cx: &LateContext<'a, 'tcx>,
+ expr: &'tcx hir::Expr,
+ _find_args: &'tcx [hir::Expr],
+ map_args: &'tcx [hir::Expr],
+) {
+ // lint if caller of `.filter().map()` is an Iterator
+ if match_trait_method(cx, &map_args[0], &paths::ITERATOR) {
+ let msg = "called `find(p).map(q)` on an `Iterator`. \
+ This is more succinctly expressed by calling `.find_map(..)` instead.";
+ span_lint(cx, FIND_MAP, expr.span, msg);
+ }
+}
+
/// lint use of `filter().map()` for `Iterators`
fn lint_filter_map_map<'a, 'tcx>(
cx: &LateContext<'a, 'tcx>,
diff --git a/tests/ui/filter_map_next.rs b/tests/ui/filter_map_next.rs
new file mode 100644
index 00000000000..f5d051be198
--- /dev/null
+++ b/tests/ui/filter_map_next.rs
@@ -0,0 +1,20 @@
+#![warn(clippy::all, clippy::pedantic)]
+
+fn main() {
+ let a = ["1", "lol", "3", "NaN", "5"];
+
+ let element: Option<i32> = a.iter().filter_map(|s| s.parse().ok()).next();
+ assert_eq!(element, Some(1));
+
+ #[rustfmt::skip]
+ let _: Option<u32> = vec![1, 2, 3, 4, 5, 6]
+ .into_iter()
+ .filter_map(|x| {
+ if x == 2 {
+ Some(x * 2)
+ } else {
+ None
+ }
+ })
+ .next();
+}
diff --git a/tests/ui/filter_map_next.stderr b/tests/ui/filter_map_next.stderr
new file mode 100644
index 00000000000..d69ae212414
--- /dev/null
+++ b/tests/ui/filter_map_next.stderr
@@ -0,0 +1,24 @@
+error: called `filter_map(p).next()` on an `Iterator`. This is more succinctly expressed by calling `.find_map(p)` instead.
+ --> $DIR/filter_map_next.rs:6:32
+ |
+LL | let element: Option<i32> = a.iter().filter_map(|s| s.parse().ok()).next();
+ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+ |
+ = note: `-D clippy::filter-map-next` implied by `-D warnings`
+ = note: replace `filter_map(|s| s.parse().ok()).next()` with `find_map(|s| s.parse().ok())`
+
+error: called `filter_map(p).next()` on an `Iterator`. This is more succinctly expressed by calling `.find_map(p)` instead.
+ --> $DIR/filter_map_next.rs:10:26
+ |
+LL | let _: Option<u32> = vec![1, 2, 3, 4, 5, 6]
+ | __________________________^
+LL | | .into_iter()
+LL | | .filter_map(|x| {
+LL | | if x == 2 {
+... |
+LL | | })
+LL | | .next();
+ | |_______________^
+
+error: aborting due to 2 previous errors
+
diff --git a/tests/ui/find_map.rs b/tests/ui/find_map.rs
new file mode 100644
index 00000000000..c28cca144ca
--- /dev/null
+++ b/tests/ui/find_map.rs
@@ -0,0 +1,32 @@
+#![warn(clippy::all, clippy::pedantic)]
+
+#[derive(Debug, Copy, Clone)]
+enum Flavor {
+ Chocolate,
+}
+
+#[derive(Debug, Copy, Clone)]
+enum Dessert {
+ Banana,
+ Pudding,
+ Cake(Flavor),
+}
+
+fn main() {
+ let desserts_of_the_week = vec![Dessert::Banana, Dessert::Cake(Flavor::Chocolate), Dessert::Pudding];
+
+ let a = ["lol", "NaN", "2", "5", "Xunda"];
+
+ let _: Option<i32> = a.iter().find(|s| s.parse::<i32>().is_ok()).map(|s| s.parse().unwrap());
+
+ let _: Option<Flavor> = desserts_of_the_week
+ .iter()
+ .find(|dessert| match *dessert {
+ Dessert::Cake(_) => true,
+ _ => false,
+ })
+ .map(|dessert| match *dessert {
+ Dessert::Cake(ref flavor) => *flavor,
+ _ => unreachable!(),
+ });
+}
diff --git a/tests/ui/find_map.stderr b/tests/ui/find_map.stderr
new file mode 100644
index 00000000000..0417c7f3dc9
--- /dev/null
+++ b/tests/ui/find_map.stderr
@@ -0,0 +1,23 @@
+error: called `find(p).map(q)` on an `Iterator`. This is more succinctly expressed by calling `.find_map(..)` instead.
+ --> $DIR/find_map.rs:20:26
+ |
+LL | let _: Option<i32> = a.iter().find(|s| s.parse::<i32>().is_ok()).map(|s| s.parse().unwrap());
+ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+ |
+ = note: `-D clippy::find-map` implied by `-D warnings`
+
+error: called `find(p).map(q)` on an `Iterator`. This is more succinctly expressed by calling `.find_map(..)` instead.
+ --> $DIR/find_map.rs:22:29
+ |
+LL | let _: Option<Flavor> = desserts_of_the_week
+ | _____________________________^
+LL | | .iter()
+LL | | .find(|dessert| match *dessert {
+LL | | Dessert::Cake(_) => true,
+... |
+LL | | _ => unreachable!(),
+LL | | });
+ | |__________^
+
+error: aborting due to 2 previous errors
+