1 use clippy_utils::diagnostics::span_lint_and_sugg;
2 use clippy_utils::source::{indent_of, reindent_multiline, snippet};
3 use clippy_utils::ty::is_type_diagnostic_item;
4 use clippy_utils::{is_trait_method, path_to_local_id, peel_blocks, SpanlessEq};
5 use if_chain::if_chain;
6 use rustc_errors::Applicability;
8 use rustc_hir::def::Res;
9 use rustc_hir::{Closure, Expr, ExprKind, PatKind, PathSegment, QPath, UnOp};
10 use rustc_lint::LateContext;
11 use rustc_middle::ty::adjustment::Adjust;
12 use rustc_span::source_map::Span;
13 use rustc_span::symbol::{sym, Symbol};
16 use super::MANUAL_FILTER_MAP;
17 use super::MANUAL_FIND_MAP;
18 use super::OPTION_FILTER_MAP;
20 fn is_method(cx: &LateContext<'_>, expr: &hir::Expr<'_>, method_name: Symbol) -> bool {
22 hir::ExprKind::Path(QPath::TypeRelative(_, mname)) => mname.ident.name == method_name,
23 hir::ExprKind::Path(QPath::Resolved(_, segments)) => {
24 segments.segments.last().unwrap().ident.name == method_name
26 hir::ExprKind::Closure(&hir::Closure { body, .. }) => {
27 let body = cx.tcx.hir().body(body);
28 let closure_expr = peel_blocks(body.value);
29 let arg_id = body.params[0].pat.hir_id;
30 match closure_expr.kind {
31 hir::ExprKind::MethodCall(hir::PathSegment { ident, .. }, receiver, ..) => {
33 if ident.name == method_name;
34 if let hir::ExprKind::Path(path) = &receiver.kind;
35 if let Res::Local(ref local) = cx.qpath_res(path, receiver.hir_id);
37 return arg_id == *local
49 fn is_option_filter_map(cx: &LateContext<'_>, filter_arg: &hir::Expr<'_>, map_arg: &hir::Expr<'_>) -> bool {
50 is_method(cx, map_arg, sym::unwrap) && is_method(cx, filter_arg, sym!(is_some))
53 /// is `filter(|x| x.is_some()).map(|x| x.unwrap())`
54 fn is_filter_some_map_unwrap(
57 filter_recv: &hir::Expr<'_>,
58 filter_arg: &hir::Expr<'_>,
59 map_arg: &hir::Expr<'_>,
61 let iterator = is_trait_method(cx, expr, sym::Iterator);
62 let option = is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(filter_recv), sym::Option);
64 (iterator || option) && is_option_filter_map(cx, filter_arg, map_arg)
67 /// lint use of `filter().map()` or `find().map()` for `Iterators`
68 #[allow(clippy::too_many_arguments)]
72 filter_recv: &hir::Expr<'_>,
73 filter_arg: &hir::Expr<'_>,
75 map_recv: &hir::Expr<'_>,
76 map_arg: &hir::Expr<'_>,
80 if is_filter_some_map_unwrap(cx, expr, filter_recv, filter_arg, map_arg) {
84 filter_span.with_hi(expr.span.hi()),
85 "`filter` for `Some` followed by `unwrap`",
86 "consider using `flatten` instead",
87 reindent_multiline(Cow::Borrowed("flatten()"), true, indent_of(cx, map_span)).into_owned(),
88 Applicability::MachineApplicable,
95 if is_trait_method(cx, map_recv, sym::Iterator);
97 // filter(|x| ...is_some())...
98 if let ExprKind::Closure(&Closure { body: filter_body_id, .. }) = filter_arg.kind;
99 let filter_body = cx.tcx.hir().body(filter_body_id);
100 if let [filter_param] = filter_body.params;
101 // optional ref pattern: `filter(|&x| ..)`
102 let (filter_pat, is_filter_param_ref) = if let PatKind::Ref(ref_pat, _) = filter_param.pat.kind {
105 (filter_param.pat, false)
107 // closure ends with is_some() or is_ok()
108 if let PatKind::Binding(_, filter_param_id, _, None) = filter_pat.kind;
109 if let ExprKind::MethodCall(path, filter_arg, [], _) = filter_body.value.kind;
110 if let Some(opt_ty) = cx.typeck_results().expr_ty(filter_arg).peel_refs().ty_adt_def();
111 if let Some(is_result) = if cx.tcx.is_diagnostic_item(sym::Option, opt_ty.did()) {
113 } else if cx.tcx.is_diagnostic_item(sym::Result, opt_ty.did()) {
118 if path.ident.name.as_str() == if is_result { "is_ok" } else { "is_some" };
120 // ...map(|x| ...unwrap())
121 if let ExprKind::Closure(&Closure { body: map_body_id, .. }) = map_arg.kind;
122 let map_body = cx.tcx.hir().body(map_body_id);
123 if let [map_param] = map_body.params;
124 if let PatKind::Binding(_, map_param_id, map_param_ident, None) = map_param.pat.kind;
125 // closure ends with expect() or unwrap()
126 if let ExprKind::MethodCall(seg, map_arg, ..) = map_body.value.kind;
127 if matches!(seg.ident.name, sym::expect | sym::unwrap | sym::unwrap_or);
129 // .filter(..).map(|y| f(y).copied().unwrap())
131 let map_arg_peeled = match map_arg.kind {
132 ExprKind::MethodCall(method, original_arg, [], _) if acceptable_methods(method) => {
138 // .filter(|x| x.is_some()).map(|y| y[.acceptable_method()].unwrap())
139 let simple_equal = path_to_local_id(filter_arg, filter_param_id)
140 && path_to_local_id(map_arg_peeled, map_param_id);
142 let eq_fallback = |a: &Expr<'_>, b: &Expr<'_>| {
143 // in `filter(|x| ..)`, replace `*x` with `x`
144 let a_path = if_chain! {
145 if !is_filter_param_ref;
146 if let ExprKind::Unary(UnOp::Deref, expr_path) = a.kind;
147 then { expr_path } else { a }
149 // let the filter closure arg and the map closure arg be equal
150 path_to_local_id(a_path, filter_param_id)
151 && path_to_local_id(b, map_param_id)
152 && cx.typeck_results().expr_ty_adjusted(a) == cx.typeck_results().expr_ty_adjusted(b)
155 if simple_equal || SpanlessEq::new(cx).expr_fallback(eq_fallback).eq_expr(filter_arg, map_arg_peeled);
157 let span = filter_span.with_hi(expr.span.hi());
158 let (filter_name, lint) = if is_find {
159 ("find", MANUAL_FIND_MAP)
161 ("filter", MANUAL_FILTER_MAP)
163 let msg = format!("`{filter_name}(..).map(..)` can be simplified as `{filter_name}_map(..)`");
164 let (to_opt, deref) = if is_result {
165 (".ok()", String::new())
167 let derefs = cx.typeck_results()
168 .expr_adjustments(map_arg)
170 .filter(|adj| matches!(adj.kind, Adjust::Deref(_)))
173 ("", "*".repeat(derefs))
176 "{filter_name}_map(|{map_param_ident}| {deref}{}{to_opt})",
177 snippet(cx, map_arg.span, ".."),
179 span_lint_and_sugg(cx, lint, span, &msg, "try", sugg, Applicability::MachineApplicable);
184 fn acceptable_methods(method: &PathSegment<'_>) -> bool {
185 let methods: [Symbol; 8] = [
196 methods.contains(&method.ident.name)