1 use clippy_utils::diagnostics::span_lint_and_sugg;
2 use clippy_utils::macros::HirNode;
3 use clippy_utils::source::{indent_of, snippet, snippet_block, snippet_with_applicability};
4 use clippy_utils::sugg::Sugg;
5 use clippy_utils::{get_parent_expr, is_refutable, peel_blocks};
6 use rustc_errors::Applicability;
7 use rustc_hir::{Arm, Expr, ExprKind, Node, PatKind};
8 use rustc_lint::LateContext;
11 use super::MATCH_SINGLE_BINDING;
14 Assign { span: Span, match_span: Span },
15 Local { span: Span, pat_span: Span },
18 #[expect(clippy::too_many_lines)]
19 pub(crate) fn check<'a>(cx: &LateContext<'a>, ex: &Expr<'a>, arms: &[Arm<'_>], expr: &Expr<'a>) {
20 if expr.span.from_expansion() || arms.len() != 1 || is_refutable(cx, arms[0].pat) {
24 let matched_vars = ex.span;
25 let bind_names = arms[0].pat.span;
26 let match_body = peel_blocks(arms[0].body);
27 let mut snippet_body = if match_body.span.from_expansion() {
28 Sugg::hir_with_macro_callsite(cx, match_body, "..").to_string()
30 snippet_block(cx, match_body.span, "..", Some(expr.span)).to_string()
33 // Do we need to add ';' to suggestion ?
34 match match_body.kind {
35 ExprKind::Block(block, _) => {
36 // macro + expr_ty(body) == ()
37 if block.span.from_expansion() && cx.typeck_results().expr_ty(match_body).is_unit() {
38 snippet_body.push(';');
42 // expr_ty(body) == ()
43 if cx.typeck_results().expr_ty(match_body).is_unit() {
44 snippet_body.push(';');
49 let mut applicability = Applicability::MaybeIncorrect;
50 match arms[0].pat.kind {
51 PatKind::Binding(..) | PatKind::Tuple(_, _) | PatKind::Struct(..) => {
52 let (target_span, sugg) = match opt_parent_assign_span(cx, ex) {
53 Some(AssignmentExpr::Assign { span, match_span }) => {
54 let sugg = sugg_with_curlies(
57 (bind_names, matched_vars),
68 "this assignment could be simplified",
69 "consider removing the `match` expression",
76 Some(AssignmentExpr::Local { span, pat_span }) => (
79 "let {} = {};\n{}let {} = {snippet_body};",
80 snippet_with_applicability(cx, bind_names, "..", &mut applicability),
81 snippet_with_applicability(cx, matched_vars, "..", &mut applicability),
82 " ".repeat(indent_of(cx, expr.span).unwrap_or(0)),
83 snippet_with_applicability(cx, pat_span, "..", &mut applicability)
87 let sugg = sugg_with_curlies(
90 (bind_names, matched_vars),
102 MATCH_SINGLE_BINDING,
104 "this match could be written as a `let` statement",
105 "consider using a `let` statement",
111 if ex.can_have_side_effects() {
112 let sugg = sugg_with_curlies(
115 (bind_names, matched_vars),
124 MATCH_SINGLE_BINDING,
126 "this match could be replaced by its scrutinee and body",
127 "consider using the scrutinee and body instead",
134 MATCH_SINGLE_BINDING,
136 "this match could be replaced by its body itself",
137 "consider using the match body instead",
139 Applicability::MachineApplicable,
147 /// Returns true if the `ex` match expression is in a local (`let`) or assign expression
148 fn opt_parent_assign_span<'a>(cx: &LateContext<'a>, ex: &Expr<'a>) -> Option<AssignmentExpr> {
149 let map = &cx.tcx.hir();
151 if let Some(Node::Expr(parent_arm_expr)) = map.find(map.get_parent_node(ex.hir_id)) {
152 return match map.find(map.get_parent_node(parent_arm_expr.hir_id)) {
153 Some(Node::Local(parent_let_expr)) => Some(AssignmentExpr::Local {
154 span: parent_let_expr.span,
155 pat_span: parent_let_expr.pat.span(),
157 Some(Node::Expr(Expr {
158 kind: ExprKind::Assign(parent_assign_expr, match_expr, _),
160 })) => Some(AssignmentExpr::Assign {
161 span: parent_assign_expr.span,
162 match_span: match_expr.span,
171 fn sugg_with_curlies<'a>(
172 cx: &LateContext<'a>,
173 (ex, match_expr): (&Expr<'a>, &Expr<'a>),
174 (bind_names, matched_vars): (Span, Span),
176 applicability: &mut Applicability,
177 assignment: Option<Span>,
178 needs_var_binding: bool,
180 let mut indent = " ".repeat(indent_of(cx, ex.span).unwrap_or(0));
182 let (mut cbrace_start, mut cbrace_end) = (String::new(), String::new());
183 if let Some(parent_expr) = get_parent_expr(cx, match_expr) {
184 if let ExprKind::Closure { .. } = parent_expr.kind {
185 cbrace_end = format!("\n{indent}}}");
186 // Fix body indent due to the closure
187 indent = " ".repeat(indent_of(cx, bind_names).unwrap_or(0));
188 cbrace_start = format!("{{\n{indent}");
192 // If the parent is already an arm, and the body is another match statement,
193 // we need curly braces around suggestion
194 let parent_node_id = cx.tcx.hir().get_parent_node(match_expr.hir_id);
195 if let Node::Arm(arm) = &cx.tcx.hir().get(parent_node_id) {
196 if let ExprKind::Match(..) = arm.body.kind {
197 cbrace_end = format!("\n{indent}}}");
198 // Fix body indent due to the match
199 indent = " ".repeat(indent_of(cx, bind_names).unwrap_or(0));
200 cbrace_start = format!("{{\n{indent}");
204 let assignment_str = assignment.map_or_else(String::new, |span| {
205 let mut s = snippet(cx, span, "..").to_string();
210 let scrutinee = if needs_var_binding {
213 snippet_with_applicability(cx, bind_names, "..", applicability),
214 snippet_with_applicability(cx, matched_vars, "..", applicability)
217 snippet_with_applicability(cx, matched_vars, "..", applicability).to_string()
220 format!("{cbrace_start}{scrutinee};\n{indent}{assignment_str}{snippet_body}{cbrace_end}")