1 use crate::utils::span_lint;
2 use rustc::lint::{EarlyContext, EarlyLintPass, LintArray, LintPass};
3 use rustc::{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.
16 /// # fn foo(bar: usize) {}
23 "Warn on unnecessary double parentheses"
26 declare_lint_pass!(DoubleParens => [DOUBLE_PARENS]);
28 impl EarlyLintPass for DoubleParens {
29 fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &Expr) {
30 if expr.span.from_expansion() {
35 ExprKind::Paren(ref in_paren) => match in_paren.kind {
36 ExprKind::Paren(_) | ExprKind::Tup(_) => {
41 "Consider removing unnecessary double parentheses",
46 ExprKind::Call(_, ref params) => {
47 if params.len() == 1 {
48 let param = ¶ms[0];
49 if let ExprKind::Paren(_) = param.kind {
54 "Consider removing unnecessary double parentheses",
59 ExprKind::MethodCall(_, ref params) => {
60 if params.len() == 2 {
61 let param = ¶ms[1];
62 if let ExprKind::Paren(_) = param.kind {
67 "Consider removing unnecessary double parentheses",