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::{Expr, ExprKind, PatKind, QPath, UnOp};
10 use rustc_lint::LateContext;
11 use rustc_middle::ty::TyS;
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<'tcx>(cx: &LateContext<'tcx>, 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(_, _, c, _, _) => {
27 let body = cx.tcx.hir().body(*c);
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, .. }, args, _) => {
33 if ident.name == method_name;
34 if let hir::ExprKind::Path(path) = &args[0].kind;
35 if let Res::Local(ref local) = cx.qpath_res(path, args[0].hir_id);
37 return arg_id == *local
49 fn is_option_filter_map<'tcx>(cx: &LateContext<'tcx>, 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 /// lint use of `filter().map()` for `Iterators`
54 fn lint_filter_some_map_unwrap(
57 filter_recv: &hir::Expr<'_>,
58 filter_arg: &hir::Expr<'_>,
59 map_arg: &hir::Expr<'_>,
63 let iterator = is_trait_method(cx, expr, sym::Iterator);
64 let option = is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(filter_recv), sym::Option);
65 if (iterator || option) && is_option_filter_map(cx, filter_arg, map_arg) {
66 let msg = "`filter` for `Some` followed by `unwrap`";
67 let help = "consider using `flatten` instead";
70 reindent_multiline(Cow::Borrowed("flatten()"), true, indent_of(cx, target_span),)
79 Applicability::MachineApplicable,
84 /// lint use of `filter().map()` or `find().map()` for `Iterators`
85 #[allow(clippy::too_many_arguments)]
86 pub(super) fn check<'tcx>(
87 cx: &LateContext<'tcx>,
89 filter_recv: &hir::Expr<'_>,
90 filter_arg: &hir::Expr<'_>,
92 map_recv: &hir::Expr<'_>,
93 map_arg: &hir::Expr<'_>,
97 lint_filter_some_map_unwrap(
104 filter_span.with_hi(expr.span.hi()),
107 if is_trait_method(cx, map_recv, sym::Iterator);
109 // filter(|x| ...is_some())...
110 if let ExprKind::Closure(_, _, filter_body_id, ..) = filter_arg.kind;
111 let filter_body = cx.tcx.hir().body(filter_body_id);
112 if let [filter_param] = filter_body.params;
113 // optional ref pattern: `filter(|&x| ..)`
114 let (filter_pat, is_filter_param_ref) = if let PatKind::Ref(ref_pat, _) = filter_param.pat.kind {
117 (filter_param.pat, false)
119 // closure ends with is_some() or is_ok()
120 if let PatKind::Binding(_, filter_param_id, _, None) = filter_pat.kind;
121 if let ExprKind::MethodCall(path, [filter_arg], _) = filter_body.value.kind;
122 if let Some(opt_ty) = cx.typeck_results().expr_ty(filter_arg).ty_adt_def();
123 if let Some(is_result) = if cx.tcx.is_diagnostic_item(sym::Option, opt_ty.did) {
125 } else if cx.tcx.is_diagnostic_item(sym::Result, opt_ty.did) {
130 if path.ident.name.as_str() == if is_result { "is_ok" } else { "is_some" };
132 // ...map(|x| ...unwrap())
133 if let ExprKind::Closure(_, _, map_body_id, ..) = map_arg.kind;
134 let map_body = cx.tcx.hir().body(map_body_id);
135 if let [map_param] = map_body.params;
136 if let PatKind::Binding(_, map_param_id, map_param_ident, None) = map_param.pat.kind;
137 // closure ends with expect() or unwrap()
138 if let ExprKind::MethodCall(seg, [map_arg, ..], _) = map_body.value.kind;
139 if matches!(seg.ident.name, sym::expect | sym::unwrap | sym::unwrap_or);
141 let eq_fallback = |a: &Expr<'_>, b: &Expr<'_>| {
142 // in `filter(|x| ..)`, replace `*x` with `x`
143 let a_path = if_chain! {
144 if !is_filter_param_ref;
145 if let ExprKind::Unary(UnOp::Deref, expr_path) = a.kind;
146 then { expr_path } else { a }
148 // let the filter closure arg and the map closure arg be equal
150 if path_to_local_id(a_path, filter_param_id);
151 if path_to_local_id(b, map_param_id);
152 if TyS::same_type(cx.typeck_results().expr_ty_adjusted(a), cx.typeck_results().expr_ty_adjusted(b));
159 if SpanlessEq::new(cx).expr_fallback(eq_fallback).eq_expr(filter_arg, map_arg);
161 let span = filter_span.with_hi(expr.span.hi());
162 let (filter_name, lint) = if is_find {
163 ("find", MANUAL_FIND_MAP)
165 ("filter", MANUAL_FILTER_MAP)
167 let msg = format!("`{}(..).map(..)` can be simplified as `{0}_map(..)`", filter_name);
168 let to_opt = if is_result { ".ok()" } else { "" };
169 let sugg = format!("{}_map(|{}| {}{})", filter_name, map_param_ident,
170 snippet(cx, map_arg.span, ".."), to_opt);
171 span_lint_and_sugg(cx, lint, span, &msg, "try", sugg, Applicability::MachineApplicable);