62 lines
1.8 KiB
Rust
62 lines
1.8 KiB
Rust
use rustc::lint::*;
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use rustc_front::hir::*;
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use rustc_front::util as ast_util;
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use utils::{SpanlessEq, span_lint};
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/// **What it does:** This lint checks for equal operands to comparison, logical and bitwise,
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/// difference and division binary operators (`==`, `>`, etc., `&&`, `||`, `&`, `|`, `^`, `-` and
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/// `/`).
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///
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/// **Why is this bad?** This is usually just a typo or a copy and paste error.
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///
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/// **Known problems:** False negatives: We had some false positives regarding calls (notably [racer](https://github.com/phildawes/racer) had one instance of `x.pop() && x.pop()`), so we removed matching any function or method calls. We may introduce a whitelist of known pure functions in the future.
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///
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/// **Example:** `x + 1 == x + 1`
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declare_lint! {
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pub EQ_OP,
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Warn,
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"equal operands on both sides of a comparison or bitwise combination (e.g. `x == x`)"
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}
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#[derive(Copy,Clone)]
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pub struct EqOp;
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impl LintPass for EqOp {
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fn get_lints(&self) -> LintArray {
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lint_array!(EQ_OP)
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}
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}
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impl LateLintPass for EqOp {
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fn check_expr(&mut self, cx: &LateContext, e: &Expr) {
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if let ExprBinary(ref op, ref left, ref right) = e.node {
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if is_valid_operator(op) && SpanlessEq::new(cx).ignore_fn().eq_expr(left, right) {
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span_lint(cx,
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EQ_OP,
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e.span,
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&format!("equal expressions as operands to `{}`", ast_util::binop_to_string(op.node)));
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}
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}
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}
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}
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fn is_valid_operator(op: &BinOp) -> bool {
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match op.node {
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BiSub |
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BiDiv |
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BiEq |
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BiLt |
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BiLe |
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BiGt |
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BiGe |
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BiNe |
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BiAnd |
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BiOr |
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BiBitXor |
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BiBitAnd |
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BiBitOr => true,
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_ => false,
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}
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}
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