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