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
|
use clippy_utils::diagnostics::span_lint_and_help;
use clippy_utils::visitors::is_local_used;
use if_chain::if_chain;
use rustc_hir::{Impl, ImplItem, ImplItemKind, ItemKind};
use rustc_lint::{LateContext, LateLintPass};
use rustc_session::{declare_tool_lint, impl_lint_pass};
declare_clippy_lint! {
/// ### What it does
/// Checks methods that contain a `self` argument but don't use it
///
/// ### Why is this bad?
/// It may be clearer to define the method as an associated function instead
/// of an instance method if it doesn't require `self`.
///
/// ### Example
/// ```rust,ignore
/// struct A;
/// impl A {
/// fn method(&self) {}
/// }
/// ```
///
/// Could be written:
///
/// ```rust,ignore
/// struct A;
/// impl A {
/// fn method() {}
/// }
/// ```
#[clippy::version = "1.40.0"]
pub UNUSED_SELF,
pedantic,
"methods that contain a `self` argument but don't use it"
}
pub struct UnusedSelf {
avoid_breaking_exported_api: bool,
}
impl_lint_pass!(UnusedSelf => [UNUSED_SELF]);
impl UnusedSelf {
pub fn new(avoid_breaking_exported_api: bool) -> Self {
Self {
avoid_breaking_exported_api,
}
}
}
impl<'tcx> LateLintPass<'tcx> for UnusedSelf {
fn check_impl_item(&mut self, cx: &LateContext<'tcx>, impl_item: &ImplItem<'_>) {
if impl_item.span.from_expansion() {
return;
}
let parent = cx.tcx.hir().get_parent_item(impl_item.hir_id());
let parent_item = cx.tcx.hir().expect_item(parent);
let assoc_item = cx.tcx.associated_item(impl_item.def_id);
if_chain! {
if let ItemKind::Impl(Impl { of_trait: None, .. }) = parent_item.kind;
if assoc_item.fn_has_self_parameter;
if let ImplItemKind::Fn(.., body_id) = &impl_item.kind;
if !cx.access_levels.is_exported(impl_item.def_id) || !self.avoid_breaking_exported_api;
let body = cx.tcx.hir().body(*body_id);
if let [self_param, ..] = body.params;
if !is_local_used(cx, body, self_param.pat.hir_id);
then {
span_lint_and_help(
cx,
UNUSED_SELF,
self_param.span,
"unused `self` argument",
None,
"consider refactoring to a associated function",
);
}
}
}
}
|
