86 lines
3.0 KiB
Rust
86 lines
3.0 KiB
Rust
use clippy_utils::diagnostics::span_lint_and_then;
|
|
use clippy_utils::source::snippet_opt;
|
|
use if_chain::if_chain;
|
|
use rustc_errors::Applicability;
|
|
use rustc_hir::{BinOpKind, Expr, ExprKind};
|
|
use rustc_lint::{LateContext, LateLintPass};
|
|
use rustc_middle::ty;
|
|
use rustc_session::{declare_lint_pass, declare_tool_lint};
|
|
|
|
declare_clippy_lint! {
|
|
/// ### What it does
|
|
/// Checks for uses of bitwise and/or operators between booleans, where performance may be improved by using
|
|
/// a lazy and.
|
|
///
|
|
/// ### Why is this bad?
|
|
/// The bitwise operators do not support short-circuiting, so it may hinder code performance.
|
|
/// Additionally, boolean logic "masked" as bitwise logic is not caught by lints like `unnecessary_fold`
|
|
///
|
|
/// ### Known problems
|
|
/// This lint evaluates only when the right side is determined to have no side effects. At this time, that
|
|
/// determination is quite conservative.
|
|
///
|
|
/// ### Example
|
|
/// ```rust
|
|
/// let (x,y) = (true, false);
|
|
/// if x & !y {} // where both x and y are booleans
|
|
/// ```
|
|
/// Use instead:
|
|
/// ```rust
|
|
/// let (x,y) = (true, false);
|
|
/// if x && !y {}
|
|
/// ```
|
|
#[clippy::version = "1.54.0"]
|
|
pub NEEDLESS_BITWISE_BOOL,
|
|
pedantic,
|
|
"Boolean expressions that use bitwise rather than lazy operators"
|
|
}
|
|
|
|
declare_lint_pass!(NeedlessBitwiseBool => [NEEDLESS_BITWISE_BOOL]);
|
|
|
|
fn is_bitwise_operation(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
|
|
let ty = cx.typeck_results().expr_ty(expr);
|
|
if_chain! {
|
|
if !expr.span.from_expansion();
|
|
if let (&ExprKind::Binary(ref op, _, right), &ty::Bool) = (&expr.kind, &ty.kind());
|
|
if op.node == BinOpKind::BitAnd || op.node == BinOpKind::BitOr;
|
|
if let ExprKind::Call(..) | ExprKind::MethodCall(..) | ExprKind::Binary(..) | ExprKind::Unary(..) = right.kind;
|
|
if !right.can_have_side_effects();
|
|
then {
|
|
return true;
|
|
}
|
|
}
|
|
false
|
|
}
|
|
|
|
fn suggession_snippet(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<String> {
|
|
if let ExprKind::Binary(ref op, left, right) = expr.kind {
|
|
if let (Some(l_snippet), Some(r_snippet)) = (snippet_opt(cx, left.span), snippet_opt(cx, right.span)) {
|
|
let op_snippet = match op.node {
|
|
BinOpKind::BitAnd => "&&",
|
|
_ => "||",
|
|
};
|
|
return Some(format!("{} {} {}", l_snippet, op_snippet, r_snippet));
|
|
}
|
|
}
|
|
None
|
|
}
|
|
|
|
impl LateLintPass<'_> for NeedlessBitwiseBool {
|
|
fn check_expr(&mut self, cx: &LateContext<'_>, expr: &Expr<'_>) {
|
|
if is_bitwise_operation(cx, expr) {
|
|
span_lint_and_then(
|
|
cx,
|
|
NEEDLESS_BITWISE_BOOL,
|
|
expr.span,
|
|
"use of bitwise operator instead of lazy operator between booleans",
|
|
|diag| {
|
|
if let Some(sugg) = suggession_snippet(cx, expr) {
|
|
diag.span_suggestion(expr.span, "try", sugg, Applicability::MachineApplicable);
|
|
}
|
|
},
|
|
);
|
|
}
|
|
}
|
|
}
|