54 lines
1.4 KiB
Rust
54 lines
1.4 KiB
Rust
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use clippy_utils::consts::{constant_simple, Constant};
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use clippy_utils::diagnostics::span_lint;
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use clippy_utils::ty::same_type_and_consts;
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use rustc_hir::{BinOpKind, Expr};
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use rustc_lint::LateContext;
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use rustc_middle::ty::TypeckResults;
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use super::ERASING_OP;
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pub(super) fn check<'tcx>(
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cx: &LateContext<'tcx>,
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e: &'tcx Expr<'_>,
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op: BinOpKind,
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left: &'tcx Expr<'_>,
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right: &'tcx Expr<'_>,
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) {
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let tck = cx.typeck_results();
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match op {
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BinOpKind::Mul | BinOpKind::BitAnd => {
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check_op(cx, tck, left, right, e);
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check_op(cx, tck, right, left, e);
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},
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BinOpKind::Div => check_op(cx, tck, left, right, e),
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_ => (),
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}
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}
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fn different_types(tck: &TypeckResults<'_>, input: &Expr<'_>, output: &Expr<'_>) -> bool {
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let input_ty = tck.expr_ty(input).peel_refs();
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let output_ty = tck.expr_ty(output).peel_refs();
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!same_type_and_consts(input_ty, output_ty)
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}
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fn check_op<'tcx>(
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cx: &LateContext<'tcx>,
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tck: &TypeckResults<'tcx>,
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op: &Expr<'tcx>,
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other: &Expr<'tcx>,
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parent: &Expr<'tcx>,
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) {
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if constant_simple(cx, tck, op) == Some(Constant::Int(0)) {
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if different_types(tck, other, parent) {
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return;
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}
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span_lint(
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cx,
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ERASING_OP,
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parent.span,
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"this operation will always return zero. This is likely not the intended outcome",
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);
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}
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}
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