1 files changed, 46 insertions, 0 deletions
diff --git a/src/tools/clippy/clippy_lints/src/methods/iter_skip_next.rs b/src/tools/clippy/clippy_lints/src/methods/iter_skip_next.rs
new file mode 100644
index 000000000..43e9451f7
--- /dev/null
+++ b/src/tools/clippy/clippy_lints/src/methods/iter_skip_next.rs
@@ -0,0 +1,46 @@
+use clippy_utils::diagnostics::span_lint_and_then;
+use clippy_utils::is_trait_method;
+use clippy_utils::path_to_local;
+use clippy_utils::source::snippet;
+use rustc_errors::Applicability;
+use rustc_hir as hir;
+use rustc_hir::{BindingAnnotation, Node, PatKind};
+use rustc_lint::LateContext;
+use rustc_span::sym;
+
+use super::ITER_SKIP_NEXT;
+
+pub(super) fn check(cx: &LateContext<'_>, expr: &hir::Expr<'_>, recv: &hir::Expr<'_>, arg: &hir::Expr<'_>) {
+    // lint if caller of skip is an Iterator
+    if is_trait_method(cx, expr, sym::Iterator) {
+        let mut application = Applicability::MachineApplicable;
+        span_lint_and_then(
+            cx,
+            ITER_SKIP_NEXT,
+            expr.span.trim_start(recv.span).unwrap(),
+            "called `skip(..).next()` on an iterator",
+            |diag| {
+                if_chain! {
+                    if let Some(id) = path_to_local(recv);
+                    if let Node::Pat(pat) = cx.tcx.hir().get(id);
+                    if let PatKind::Binding(ann, _, _, _)  = pat.kind;
+                    if ann != BindingAnnotation::Mutable;
+                    then {
+                        application = Applicability::Unspecified;
+                        diag.span_help(
+                            pat.span,
+                            &format!("for this change `{}` has to be mutable", snippet(cx, pat.span, "..")),
+                        );
+                    }
+                }
+
+                diag.span_suggestion(
+                    expr.span.trim_start(recv.span).unwrap(),
+                    "use `nth` instead",
+                    format!(".nth({})", snippet(cx, arg.span, "..")),
+                    application,
+                );
+            },
+        );
+    }
+}