1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
|
use clippy_utils::consts::{constant_simple, Constant};
use clippy_utils::diagnostics::span_lint;
use clippy_utils::ty::same_type_and_consts;
use rustc_hir::{BinOpKind, Expr};
use rustc_lint::LateContext;
use rustc_middle::ty::TypeckResults;
use super::ERASING_OP;
pub(super) fn check<'tcx>(
cx: &LateContext<'tcx>,
e: &'tcx Expr<'_>,
op: BinOpKind,
left: &'tcx Expr<'_>,
right: &'tcx Expr<'_>,
) {
let tck = cx.typeck_results();
match op {
BinOpKind::Mul | BinOpKind::BitAnd => {
check_op(cx, tck, left, right, e);
check_op(cx, tck, right, left, e);
},
BinOpKind::Div => check_op(cx, tck, left, right, e),
_ => (),
}
}
fn different_types(tck: &TypeckResults<'_>, input: &Expr<'_>, output: &Expr<'_>) -> bool {
let input_ty = tck.expr_ty(input).peel_refs();
let output_ty = tck.expr_ty(output).peel_refs();
!same_type_and_consts(input_ty, output_ty)
}
fn check_op<'tcx>(
cx: &LateContext<'tcx>,
tck: &TypeckResults<'tcx>,
op: &Expr<'tcx>,
other: &Expr<'tcx>,
parent: &Expr<'tcx>,
) {
if constant_simple(cx, tck, op) == Some(Constant::Int(0)) {
if different_types(tck, other, parent) {
return;
}
span_lint(
cx,
ERASING_OP,
parent.span,
"this operation will always return zero. This is likely not the intended outcome",
);
}
}
|
