66 lines
2.0 KiB
Rust
66 lines
2.0 KiB
Rust
use rustc::lint::*;
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use rustc_front::hir::*;
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use syntax::codemap::Spanned;
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use syntax::ast::Lit_::*;
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use utils::span_lint;
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declare_lint!(pub PRECEDENCE, Warn,
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"catches operations where precedence may be unclear. See the wiki for a \
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list of cases caught");
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#[derive(Copy,Clone)]
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pub struct Precedence;
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impl LintPass for Precedence {
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fn get_lints(&self) -> LintArray {
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lint_array!(PRECEDENCE)
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}
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fn check_expr(&mut self, cx: &Context, expr: &Expr) {
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if let ExprBinary(Spanned { node: op, ..}, ref left, ref right) = expr.node {
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if is_bit_op(op) && (is_arith_expr(left) || is_arith_expr(right)) {
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span_lint(cx, PRECEDENCE, expr.span,
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"operator precedence can trip the unwary. Consider adding parentheses \
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to the subexpression");
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}
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}
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if let ExprUnary(UnNeg, ref rhs) = expr.node {
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if let ExprMethodCall(_, _, ref args) = rhs.node {
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if let Some(slf) = args.first() {
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if let ExprLit(ref lit) = slf.node {
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match lit.node {
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LitInt(..) | LitFloat(..) | LitFloatUnsuffixed(..) =>
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span_lint(cx, PRECEDENCE, expr.span,
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"unary minus has lower precedence than method call. Consider \
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adding parentheses to clarify your intent"),
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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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}
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}
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fn is_arith_expr(expr : &Expr) -> bool {
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match expr.node {
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ExprBinary(Spanned { node: op, ..}, _, _) => is_arith_op(op),
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_ => false
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}
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}
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fn is_bit_op(op : BinOp_) -> bool {
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match op {
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BiBitXor | BiBitAnd | BiBitOr | BiShl | BiShr => true,
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_ => false
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}
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}
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fn is_arith_op(op : BinOp_) -> bool {
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match op {
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BiAdd | BiSub | BiMul | BiDiv | BiRem => true,
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_ => false
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}
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}
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