rust-clippy/clippy_lints/src/double_parens.rs

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use crate::syntax::ast::*;
use crate::rustc::lint::{EarlyContext, EarlyLintPass, LintArray, LintContext, LintPass};
use crate::rustc::{declare_tool_lint, lint_array};
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/// **What it does:** Checks for unnecessary double parentheses.
///
/// **Why is this bad?** This makes code harder to read and might indicate a
/// mistake.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// ((0))
/// foo((0))
/// ((1, 2))
/// ```
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declare_clippy_lint! {
pub DOUBLE_PARENS,
complexity,
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"Warn on unnecessary double parentheses"
}
#[derive(Copy, Clone)]
pub struct DoubleParens;
impl LintPass for DoubleParens {
fn get_lints(&self) -> LintArray {
lint_array!(DOUBLE_PARENS)
}
}
impl EarlyLintPass for DoubleParens {
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fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &Expr) {
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match expr.node {
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ExprKind::Paren(ref in_paren) => match in_paren.node {
ExprKind::Paren(_) | ExprKind::Tup(_) => {
cx.span_lint(DOUBLE_PARENS, expr.span, "Consider removing unnecessary double parentheses");
},
_ => {},
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},
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ExprKind::Call(_, ref params) => if params.len() == 1 {
let param = &params[0];
if let ExprKind::Paren(_) = param.node {
cx.span_lint(DOUBLE_PARENS, param.span, "Consider removing unnecessary double parentheses");
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}
},
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ExprKind::MethodCall(_, ref params) => if params.len() == 2 {
let param = &params[1];
if let ExprKind::Paren(_) = param.node {
cx.span_lint(DOUBLE_PARENS, param.span, "Consider removing unnecessary double parentheses");
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}
},
_ => {},
}
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}
}