1 use clippy_utils::diagnostics::span_lint_and_sugg;
2 use clippy_utils::is_trait_method;
3 use rustc_errors::Applicability;
5 use rustc_lint::LateContext;
7 use rustc_span::{source_map::Span, sym};
9 use super::FLAT_MAP_OPTION;
10 use clippy_utils::ty::is_type_diagnostic_item;
12 pub(super) fn check<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>, arg: &'tcx hir::Expr<'_>, span: Span) {
13 if !is_trait_method(cx, expr, sym::Iterator) {
16 let arg_ty = cx.typeck_results().expr_ty_adjusted(arg);
17 let sig = match arg_ty.kind() {
18 ty::Closure(_, substs) => substs.as_closure().sig(),
19 _ if arg_ty.is_fn() => arg_ty.fn_sig(cx.tcx),
22 if !is_type_diagnostic_item(cx, sig.output().skip_binder(), sym::option_type) {
29 "used `flat_map` where `filter_map` could be used instead",
32 Applicability::MachineApplicable,