rust-clippy/clippy_lints/src/double_parens.rs

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use crate::utils::{in_macro, span_lint};
use rustc::lint::{EarlyContext, EarlyLintPass, LintArray, LintPass};
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use rustc::{declare_lint_pass, declare_tool_lint};
use syntax::ast::*;
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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.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// ((0))
/// foo((0))
/// ((1, 2))
/// ```
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pub DOUBLE_PARENS,
complexity,
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"Warn on unnecessary double parentheses"
}
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declare_lint_pass!(DoubleParens => [DOUBLE_PARENS]);
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impl EarlyLintPass for DoubleParens {
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fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &Expr) {
if in_macro(expr.span) {
return;
}
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match expr.node {
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ExprKind::Paren(ref in_paren) => match in_paren.node {
ExprKind::Paren(_) | ExprKind::Tup(_) => {
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span_lint(
cx,
DOUBLE_PARENS,
expr.span,
"Consider removing unnecessary double parentheses",
);
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},
_ => {},
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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 {
span_lint(
cx,
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 {
span_lint(
cx,
DOUBLE_PARENS,
param.span,
"Consider removing unnecessary double parentheses",
);
}
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}
},
_ => {},
}
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}
}