| use clippy_utils::diagnostics::span_lint; |
| use rustc_ast::ast::{Expr, ExprKind}; |
| use rustc_lint::{EarlyContext, EarlyLintPass}; |
| use rustc_session::{declare_lint_pass, declare_tool_lint}; |
| |
| declare_clippy_lint! { |
| /// ### What it does |
| /// Checks for unnecessary double parentheses. |
| /// |
| /// ### Why is this bad? |
| /// This makes code harder to read and might indicate a |
| /// mistake. |
| /// |
| /// ### Example |
| /// ```no_run |
| /// fn simple_double_parens() -> i32 { |
| /// ((0)) |
| /// } |
| /// |
| /// # fn foo(bar: usize) {} |
| /// foo((0)); |
| /// ``` |
| /// |
| /// Use instead: |
| /// ```no_run |
| /// fn simple_no_parens() -> i32 { |
| /// 0 |
| /// } |
| /// |
| /// # fn foo(bar: usize) {} |
| /// foo(0); |
| /// ``` |
| #[clippy::version = "pre 1.29.0"] |
| pub DOUBLE_PARENS, |
| complexity, |
| "Warn on unnecessary double parentheses" |
| } |
| |
| declare_lint_pass!(DoubleParens => [DOUBLE_PARENS]); |
| |
| impl EarlyLintPass for DoubleParens { |
| fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &Expr) { |
| if expr.span.from_expansion() { |
| return; |
| } |
| |
| let msg: &str = "consider removing unnecessary double parentheses"; |
| |
| match expr.kind { |
| ExprKind::Paren(ref in_paren) => match in_paren.kind { |
| ExprKind::Paren(_) | ExprKind::Tup(_) => { |
| span_lint(cx, DOUBLE_PARENS, expr.span, msg); |
| }, |
| _ => {}, |
| }, |
| ExprKind::Call(_, ref params) => { |
| if params.len() == 1 { |
| let param = ¶ms[0]; |
| if let ExprKind::Paren(_) = param.kind { |
| span_lint(cx, DOUBLE_PARENS, param.span, msg); |
| } |
| } |
| }, |
| ExprKind::MethodCall(ref call) => { |
| if let [ref arg] = call.args[..] { |
| if let ExprKind::Paren(_) = arg.kind { |
| span_lint(cx, DOUBLE_PARENS, arg.span, msg); |
| } |
| } |
| }, |
| _ => {}, |
| } |
| } |
| } |