1 use crate::utils::span_lint;
2 use rustc_ast::ast::{Expr, ExprKind};
3 use rustc_lint::{EarlyContext, EarlyLintPass};
4 use rustc_session::{declare_lint_pass, declare_tool_lint};
7 /// **What it does:** Checks for unnecessary double parentheses.
9 /// **Why is this bad?** This makes code harder to read and might indicate a
12 /// **Known problems:** None.
17 /// fn simple_double_parens() -> i32 {
22 /// fn simple_no_parens() -> i32 {
28 /// # fn foo(bar: usize) {}
37 "Warn on unnecessary double parentheses"
40 declare_lint_pass!(DoubleParens => [DOUBLE_PARENS]);
42 impl EarlyLintPass for DoubleParens {
43 fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &Expr) {
44 if expr.span.from_expansion() {
49 ExprKind::Paren(ref in_paren) => match in_paren.kind {
50 ExprKind::Paren(_) | ExprKind::Tup(_) => {
55 "Consider removing unnecessary double parentheses",
60 ExprKind::Call(_, ref params) => {
61 if params.len() == 1 {
62 let param = ¶ms[0];
63 if let ExprKind::Paren(_) = param.kind {
68 "Consider removing unnecessary double parentheses",
73 ExprKind::MethodCall(_, ref params, _) => {
74 if params.len() == 2 {
75 let param = ¶ms[1];
76 if let ExprKind::Paren(_) = param.kind {
81 "Consider removing unnecessary double parentheses",