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
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
use crate::rule_prelude::*;
declare_lint! {
#[derive(Default)]
NoCompareNegZero,
errors,
"no-compare-neg-zero"
}
#[typetag::serde]
impl CstRule for NoCompareNegZero {
fn check_node(&self, node: &SyntaxNode, ctx: &mut RuleCtx) -> Option<()> {
if node.try_to::<ast::BinExpr>()?.comparison() {
let bin = node.to::<ast::BinExpr>();
let op = bin.op_token().unwrap();
if let Some(expr) = bin
.lhs()
.filter(|e| unsafe_comparison(e))
.and_then(|_| bin.rhs())
{
issue_err(expr, ctx, op.clone(), node);
}
if let Some(expr) = bin
.rhs()
.filter(|e| unsafe_comparison(e))
.and_then(|_| bin.lhs())
{
issue_err(expr, ctx, op, node)
}
}
None
}
}
fn issue_err(expr: ast::Expr, ctx: &mut RuleCtx, op: SyntaxToken, parent: &SyntaxNode) {
let err = ctx
.err(
"no-compare-neg-zero",
format!(
"comparison against `-0` with `{}` yields unexpected behavior",
expr.text()
),
)
.primary(
op,
"...because this comparison passes for both `-0` and `+0`",
)
.suggestion(
parent,
"try using `Object.is` instead",
format!("Object.is({}, -0)", expr.syntax().text()),
Applicability::MaybeIncorrect,
);
ctx.fix()
.replace(parent, format!("Object.is({}, -0)", expr.text()));
ctx.add_err(err);
}
fn unsafe_comparison(expr: &ast::Expr) -> bool {
expr.syntax().text() == "-0"
}
rule_tests! {
NoCompareNegZero::default(),
err: {
"x == -0",
"x != -0",
"x === -0",
"-0 === -0",
"-0 == x",
"-0 >= 1",
"x < -0",
"x !== -0"
},
ok: {
"x === 0",
"0 === 0",
"Object.is(x, -0)"
}
}