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use rustc ::lint ::* ;
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use rustc_front ::hir ::* ;
use rustc_front ::util as ast_util ;
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use utils ::{ is_exp_equal , span_lint } ;
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/// **What it does:** This lint checks for equal operands to comparison, logical and bitwise,
/// difference and division binary operators (`==`, `>`, etc., `&&`, `||`, `&`, `|`, `^`, `-` and
/// `/`).
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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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///
/// **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.
///
/// **Example:** `x + 1 == x + 1`
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declare_lint! {
pub EQ_OP ,
Warn ,
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" equal operands on both sides of a comparison or bitwise combination (e.g. `x == x`) "
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}
#[ derive(Copy,Clone) ]
pub struct EqOp ;
impl LintPass for EqOp {
fn get_lints ( & self ) -> LintArray {
lint_array! ( EQ_OP )
}
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}
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impl LateLintPass for EqOp {
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 ) & & is_exp_equal ( cx , left , right , true ) {
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span_lint ( cx ,
EQ_OP ,
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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fn is_valid_operator ( op : & BinOp ) -> bool {
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match op . node {
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BiSub |
BiDiv |
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BiEq |
BiLt |
BiLe |
BiGt |
BiGe |
BiNe |
BiAnd |
BiOr |
BiBitXor |
BiBitAnd |
BiBitOr = > true ,
_ = > false ,
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}
}