1 use clippy_utils::diagnostics::span_lint_and_then;
2 use clippy_utils::in_macro;
3 use clippy_utils::source::snippet_opt;
4 use if_chain::if_chain;
5 use rustc_errors::Applicability;
6 use rustc_hir::{BinOpKind, Expr, ExprKind};
7 use rustc_lint::{LateContext, LateLintPass};
9 use rustc_session::{declare_lint_pass, declare_tool_lint};
11 declare_clippy_lint! {
13 /// Checks for uses of bitwise and/or operators between booleans, where performance may be improved by using
16 /// **Why is this bad?**
17 /// The bitwise operators do not support short-circuiting, so it may hinder code performance.
18 /// Additionally, boolean logic "masked" as bitwise logic is not caught by lints like `unnecessary_fold`
20 /// **Known problems:**
21 /// This lint evaluates only when the right side is determined to have no side effects. At this time, that
22 /// determination is quite conservative.
27 /// let (x,y) = (true, false);
28 /// if x & !y {} // where both x and y are booleans
32 /// let (x,y) = (true, false);
35 pub NEEDLESS_BITWISE_BOOL,
37 "Boolean expressions that use bitwise rather than lazy operators"
40 declare_lint_pass!(NeedlessBitwiseBool => [NEEDLESS_BITWISE_BOOL]);
42 fn is_bitwise_operation(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
43 let ty = cx.typeck_results().expr_ty(expr);
45 if !in_macro(expr.span);
46 if let (&ExprKind::Binary(ref op, _, right), &ty::Bool) = (&expr.kind, &ty.kind());
47 if op.node == BinOpKind::BitAnd || op.node == BinOpKind::BitOr;
48 if let ExprKind::Call(..) | ExprKind::MethodCall(..) | ExprKind::Binary(..) | ExprKind::Unary(..) = right.kind;
49 if !right.can_have_side_effects();
57 fn suggession_snippet(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<String> {
58 if let ExprKind::Binary(ref op, left, right) = expr.kind {
59 if let (Some(l_snippet), Some(r_snippet)) = (snippet_opt(cx, left.span), snippet_opt(cx, right.span)) {
60 let op_snippet = match op.node {
61 BinOpKind::BitAnd => "&&",
64 return Some(format!("{} {} {}", l_snippet, op_snippet, r_snippet));
70 impl LateLintPass<'_> for NeedlessBitwiseBool {
71 fn check_expr(&mut self, cx: &LateContext<'_>, expr: &Expr<'_>) {
72 if is_bitwise_operation(cx, expr) {
75 NEEDLESS_BITWISE_BOOL,
77 "use of bitwise operator instead of lazy operator between booleans",
79 if let Some(sugg) = suggession_snippet(cx, expr) {
80 diag.span_suggestion(expr.span, "try", sugg, Applicability::MachineApplicable);