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
112
113
114
115
116
|
use clippy_utils::diagnostics::span_lint;
use clippy_utils::{binop_traits, trait_ref_of_method, BINOP_TRAITS, OP_ASSIGN_TRAITS};
use if_chain::if_chain;
use rustc_hir as hir;
use rustc_hir::intravisit::{walk_expr, Visitor};
use rustc_lint::{LateContext, LateLintPass};
use rustc_session::{declare_lint_pass, declare_tool_lint};
declare_clippy_lint! {
/// ### What it does
/// Lints for suspicious operations in impls of arithmetic operators, e.g.
/// subtracting elements in an Add impl.
///
/// ### Why is this bad?
/// This is probably a typo or copy-and-paste error and not intended.
///
/// ### Example
/// ```ignore
/// impl Add for Foo {
/// type Output = Foo;
///
/// fn add(self, other: Foo) -> Foo {
/// Foo(self.0 - other.0)
/// }
/// }
/// ```
#[clippy::version = "pre 1.29.0"]
pub SUSPICIOUS_ARITHMETIC_IMPL,
suspicious,
"suspicious use of operators in impl of arithmetic trait"
}
declare_clippy_lint! {
/// ### What it does
/// Lints for suspicious operations in impls of OpAssign, e.g.
/// subtracting elements in an AddAssign impl.
///
/// ### Why is this bad?
/// This is probably a typo or copy-and-paste error and not intended.
///
/// ### Example
/// ```ignore
/// impl AddAssign for Foo {
/// fn add_assign(&mut self, other: Foo) {
/// *self = *self - other;
/// }
/// }
/// ```
#[clippy::version = "pre 1.29.0"]
pub SUSPICIOUS_OP_ASSIGN_IMPL,
suspicious,
"suspicious use of operators in impl of OpAssign trait"
}
declare_lint_pass!(SuspiciousImpl => [SUSPICIOUS_ARITHMETIC_IMPL, SUSPICIOUS_OP_ASSIGN_IMPL]);
impl<'tcx> LateLintPass<'tcx> for SuspiciousImpl {
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>) {
if_chain! {
if let hir::ExprKind::Binary(binop, _, _) | hir::ExprKind::AssignOp(binop, ..) = expr.kind;
if let Some((binop_trait_lang, op_assign_trait_lang)) = binop_traits(binop.node);
if let Ok(binop_trait_id) = cx.tcx.lang_items().require(binop_trait_lang);
if let Ok(op_assign_trait_id) = cx.tcx.lang_items().require(op_assign_trait_lang);
// Check for more than one binary operation in the implemented function
// Linting when multiple operations are involved can result in false positives
let parent_fn = cx.tcx.hir().get_parent_item(expr.hir_id);
if let hir::Node::ImplItem(impl_item) = cx.tcx.hir().get_by_def_id(parent_fn);
if let hir::ImplItemKind::Fn(_, body_id) = impl_item.kind;
let body = cx.tcx.hir().body(body_id);
let parent_fn = cx.tcx.hir().get_parent_item(expr.hir_id);
if let Some(trait_ref) = trait_ref_of_method(cx, parent_fn);
let trait_id = trait_ref.path.res.def_id();
if ![binop_trait_id, op_assign_trait_id].contains(&trait_id);
if let Some(&(_, lint)) = [
(&BINOP_TRAITS, SUSPICIOUS_ARITHMETIC_IMPL),
(&OP_ASSIGN_TRAITS, SUSPICIOUS_OP_ASSIGN_IMPL),
]
.iter()
.find(|&(ts, _)| ts.iter().any(|&t| Ok(trait_id) == cx.tcx.lang_items().require(t)));
if count_binops(body.value) == 1;
then {
span_lint(
cx,
lint,
binop.span,
&format!("suspicious use of `{}` in `{}` impl", binop.node.as_str(), cx.tcx.item_name(trait_id)),
);
}
}
}
}
fn count_binops(expr: &hir::Expr<'_>) -> u32 {
let mut visitor = BinaryExprVisitor::default();
visitor.visit_expr(expr);
visitor.nb_binops
}
#[derive(Default)]
struct BinaryExprVisitor {
nb_binops: u32,
}
impl<'tcx> Visitor<'tcx> for BinaryExprVisitor {
fn visit_expr(&mut self, expr: &'tcx hir::Expr<'_>) {
match expr.kind {
hir::ExprKind::Binary(..)
| hir::ExprKind::Unary(hir::UnOp::Not | hir::UnOp::Neg, _)
| hir::ExprKind::AssignOp(..) => self.nb_binops += 1,
_ => {},
}
walk_expr(self, expr);
}
}
|
