Don't lint closures in arg_iter

Author: smoelius

examples/supplementary/arg_iter/src/lib.rs

@@ -65,12 +65,16 @@ impl<'tcx> LateLintPass<'tcx> for ArgIter {
     fn check_fn(
         &mut self,
         cx: &LateContext<'tcx>,
-        _kind: FnKind<'tcx>,
+        kind: FnKind<'tcx>,
         decl: &'tcx FnDecl<'tcx>,
         _body: &'tcx Body<'tcx>,
         span: Span,
         id: LocalDefId,
     ) {
+        if matches!(kind, FnKind::Closure) {
+            return;
+        }
+
         // Don't lint functions generated by macros (e.g. derive, attribute macros)
         if span.from_expansion() {
             return;