diff --git a/clippy_lints/src/methods/mod.rs b/clippy_lints/src/methods/mod.rs index 97cc58023f5..56686f6d24f 100644 --- a/clippy_lints/src/methods/mod.rs +++ b/clippy_lints/src/methods/mod.rs @@ -1408,7 +1408,7 @@ impl<'tcx> LateLintPass<'tcx> for Methods { ["nth", "iter_mut"] => lint_iter_nth(cx, expr, &arg_lists, true), ["nth", ..] => lint_iter_nth_zero(cx, expr, arg_lists[0]), ["step_by", ..] => lint_step_by(cx, expr, arg_lists[0]), - ["next", "skip"] => lint_iter_skip_next(cx, expr), + ["next", "skip"] => lint_iter_skip_next(cx, expr, arg_lists[1]), ["collect", "cloned"] => lint_iter_cloned_collect(cx, expr, arg_lists[1]), ["as_ref"] => lint_asref(cx, expr, "as_ref", arg_lists[0]), ["as_mut"] => lint_asref(cx, expr, "as_mut", arg_lists[0]), @@ -2436,17 +2436,21 @@ fn lint_get_unwrap<'tcx>(cx: &LateContext<'tcx>, expr: &hir::Expr<'_>, get_args: ); } -fn lint_iter_skip_next(cx: &LateContext<'_>, expr: &hir::Expr<'_>) { +fn lint_iter_skip_next(cx: &LateContext<'_>, expr: &hir::Expr<'_>, skip_args: &[hir::Expr<'_>]) { // lint if caller of skip is an Iterator if match_trait_method(cx, expr, &paths::ITERATOR) { - span_lint_and_help( - cx, - ITER_SKIP_NEXT, - expr.span, - "called `skip(x).next()` on an iterator", - None, - "this is more succinctly expressed by calling `nth(x)`", - ); + if let [caller, n] = skip_args { + let hint = format!(".nth({})", snippet(cx, n.span, "..")); + span_lint_and_sugg( + cx, + ITER_SKIP_NEXT, + expr.span.trim_start(caller.span).unwrap(), + "called `skip(x).next()` on an iterator", + "use `nth` instead", + hint, + Applicability::MachineApplicable, + ); + } } } diff --git a/tests/ui/iter_skip_next.fixed b/tests/ui/iter_skip_next.fixed new file mode 100644 index 00000000000..928b6acb951 --- /dev/null +++ b/tests/ui/iter_skip_next.fixed @@ -0,0 +1,22 @@ +// run-rustfix +// aux-build:option_helpers.rs + +#![warn(clippy::iter_skip_next)] +#![allow(clippy::blacklisted_name)] +#![allow(clippy::iter_nth)] + +extern crate option_helpers; + +use option_helpers::IteratorFalsePositives; + +/// Checks implementation of `ITER_SKIP_NEXT` lint +fn main() { + let some_vec = vec![0, 1, 2, 3]; + let _ = some_vec.iter().nth(42); + let _ = some_vec.iter().cycle().nth(42); + let _ = (1..10).nth(10); + let _ = &some_vec[..].iter().nth(3); + let foo = IteratorFalsePositives { foo: 0 }; + let _ = foo.skip(42).next(); + let _ = foo.filter().skip(42).next(); +} diff --git a/tests/ui/iter_skip_next.rs b/tests/ui/iter_skip_next.rs index a65ca3bbb13..7075e2598eb 100644 --- a/tests/ui/iter_skip_next.rs +++ b/tests/ui/iter_skip_next.rs @@ -1,15 +1,17 @@ +// run-rustfix // aux-build:option_helpers.rs #![warn(clippy::iter_skip_next)] #![allow(clippy::blacklisted_name)] +#![allow(clippy::iter_nth)] extern crate option_helpers; use option_helpers::IteratorFalsePositives; /// Checks implementation of `ITER_SKIP_NEXT` lint -fn iter_skip_next() { - let mut some_vec = vec![0, 1, 2, 3]; +fn main() { + let some_vec = vec![0, 1, 2, 3]; let _ = some_vec.iter().skip(42).next(); let _ = some_vec.iter().cycle().skip(42).next(); let _ = (1..10).skip(10).next(); @@ -18,5 +20,3 @@ fn iter_skip_next() { let _ = foo.skip(42).next(); let _ = foo.filter().skip(42).next(); } - -fn main() {} diff --git a/tests/ui/iter_skip_next.stderr b/tests/ui/iter_skip_next.stderr index 5709f335529..feedc2f288a 100644 --- a/tests/ui/iter_skip_next.stderr +++ b/tests/ui/iter_skip_next.stderr @@ -1,35 +1,28 @@ error: called `skip(x).next()` on an iterator - --> $DIR/iter_skip_next.rs:13:13 + --> $DIR/iter_skip_next.rs:15:28 | LL | let _ = some_vec.iter().skip(42).next(); - | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + | ^^^^^^^^^^^^^^^^ help: use `nth` instead: `.nth(42)` | = note: `-D clippy::iter-skip-next` implied by `-D warnings` - = help: this is more succinctly expressed by calling `nth(x)` error: called `skip(x).next()` on an iterator - --> $DIR/iter_skip_next.rs:14:13 + --> $DIR/iter_skip_next.rs:16:36 | LL | let _ = some_vec.iter().cycle().skip(42).next(); - | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ - | - = help: this is more succinctly expressed by calling `nth(x)` + | ^^^^^^^^^^^^^^^^ help: use `nth` instead: `.nth(42)` error: called `skip(x).next()` on an iterator - --> $DIR/iter_skip_next.rs:15:13 + --> $DIR/iter_skip_next.rs:17:20 | LL | let _ = (1..10).skip(10).next(); - | ^^^^^^^^^^^^^^^^^^^^^^^ - | - = help: this is more succinctly expressed by calling `nth(x)` + | ^^^^^^^^^^^^^^^^ help: use `nth` instead: `.nth(10)` error: called `skip(x).next()` on an iterator - --> $DIR/iter_skip_next.rs:16:14 + --> $DIR/iter_skip_next.rs:18:33 | LL | let _ = &some_vec[..].iter().skip(3).next(); - | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ - | - = help: this is more succinctly expressed by calling `nth(x)` + | ^^^^^^^^^^^^^^^ help: use `nth` instead: `.nth(3)` error: aborting due to 4 previous errors