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
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
|
use clippy_config::msrvs::{self, Msrv};
use clippy_utils::diagnostics::span_lint_and_sugg;
use clippy_utils::source::snippet_with_applicability;
use clippy_utils::ty::{is_copy, is_type_diagnostic_item};
use clippy_utils::{is_diag_trait_item, match_def_path, paths, peel_blocks};
use rustc_errors::Applicability;
use rustc_hir as hir;
use rustc_hir::def_id::DefId;
use rustc_lint::LateContext;
use rustc_middle::mir::Mutability;
use rustc_middle::ty;
use rustc_middle::ty::adjustment::Adjust;
use rustc_span::symbol::Ident;
use rustc_span::{sym, Span};
use super::MAP_CLONE;
// If this `map` is called on an `Option` or a `Result` and the previous call is `as_ref`, we don't
// run this lint because it would overlap with `useless_asref` which provides a better suggestion
// in this case.
fn should_run_lint(cx: &LateContext<'_>, e: &hir::Expr<'_>, method_id: DefId) -> bool {
if is_diag_trait_item(cx, method_id, sym::Iterator) {
return true;
}
// We check if it's an `Option` or a `Result`.
if let Some(id) = cx.tcx.impl_of_method(method_id) {
let identity = cx.tcx.type_of(id).instantiate_identity();
if !is_type_diagnostic_item(cx, identity, sym::Option) && !is_type_diagnostic_item(cx, identity, sym::Result) {
return false;
}
} else {
return false;
}
// We check if the previous method call is `as_ref`.
if let hir::ExprKind::MethodCall(path1, receiver, _, _) = &e.kind
&& let hir::ExprKind::MethodCall(path2, _, _, _) = &receiver.kind
{
return path2.ident.name != sym::as_ref || path1.ident.name != sym::map;
}
true
}
pub(super) fn check(cx: &LateContext<'_>, e: &hir::Expr<'_>, recv: &hir::Expr<'_>, arg: &hir::Expr<'_>, msrv: &Msrv) {
if let Some(method_id) = cx.typeck_results().type_dependent_def_id(e.hir_id)
&& should_run_lint(cx, e, method_id)
{
match arg.kind {
hir::ExprKind::Closure(&hir::Closure { body, .. }) => {
let closure_body = cx.tcx.hir().body(body);
let closure_expr = peel_blocks(closure_body.value);
match closure_body.params[0].pat.kind {
hir::PatKind::Ref(inner, hir::Mutability::Not) => {
if let hir::PatKind::Binding(hir::BindingAnnotation::NONE, .., name, None) = inner.kind {
if ident_eq(name, closure_expr) {
lint_explicit_closure(cx, e.span, recv.span, true, msrv);
}
}
},
hir::PatKind::Binding(hir::BindingAnnotation::NONE, .., name, None) => {
match closure_expr.kind {
hir::ExprKind::Unary(hir::UnOp::Deref, inner) => {
if ident_eq(name, inner) {
if let ty::Ref(.., Mutability::Not) = cx.typeck_results().expr_ty(inner).kind() {
lint_explicit_closure(cx, e.span, recv.span, true, msrv);
}
}
},
hir::ExprKind::MethodCall(method, obj, [], _) => {
if ident_eq(name, obj) && method.ident.name == sym::clone
&& let Some(fn_id) = cx.typeck_results().type_dependent_def_id(closure_expr.hir_id)
&& let Some(trait_id) = cx.tcx.trait_of_item(fn_id)
&& cx.tcx.lang_items().clone_trait().map_or(false, |id| id == trait_id)
// no autoderefs
&& !cx.typeck_results().expr_adjustments(obj).iter()
.any(|a| matches!(a.kind, Adjust::Deref(Some(..))))
{
let obj_ty = cx.typeck_results().expr_ty(obj);
if let ty::Ref(_, ty, mutability) = obj_ty.kind() {
if matches!(mutability, Mutability::Not) {
let copy = is_copy(cx, *ty);
lint_explicit_closure(cx, e.span, recv.span, copy, msrv);
}
} else {
lint_needless_cloning(cx, e.span, recv.span);
}
}
},
hir::ExprKind::Call(call, [_]) => {
if let hir::ExprKind::Path(qpath) = call.kind {
handle_path(cx, call, &qpath, e, recv);
}
},
_ => {},
}
},
_ => {},
}
},
hir::ExprKind::Path(qpath) => handle_path(cx, arg, &qpath, e, recv),
_ => {},
}
}
}
fn handle_path(
cx: &LateContext<'_>,
arg: &hir::Expr<'_>,
qpath: &hir::QPath<'_>,
e: &hir::Expr<'_>,
recv: &hir::Expr<'_>,
) {
if let Some(path_def_id) = cx.qpath_res(qpath, arg.hir_id).opt_def_id()
&& match_def_path(cx, path_def_id, &paths::CLONE_TRAIT_METHOD)
{
// FIXME: It would be better to infer the type to check if it's copyable or not
// to suggest to use `.copied()` instead of `.cloned()` where applicable.
lint_path(cx, e.span, recv.span);
}
}
fn ident_eq(name: Ident, path: &hir::Expr<'_>) -> bool {
if let hir::ExprKind::Path(hir::QPath::Resolved(None, path)) = path.kind {
path.segments.len() == 1 && path.segments[0].ident == name
} else {
false
}
}
fn lint_needless_cloning(cx: &LateContext<'_>, root: Span, receiver: Span) {
span_lint_and_sugg(
cx,
MAP_CLONE,
root.trim_start(receiver).unwrap(),
"you are needlessly cloning iterator elements",
"remove the `map` call",
String::new(),
Applicability::MachineApplicable,
);
}
fn lint_path(cx: &LateContext<'_>, replace: Span, root: Span) {
let mut applicability = Applicability::MachineApplicable;
span_lint_and_sugg(
cx,
MAP_CLONE,
replace,
"you are explicitly cloning with `.map()`",
"consider calling the dedicated `cloned` method",
format!(
"{}.cloned()",
snippet_with_applicability(cx, root, "..", &mut applicability),
),
applicability,
);
}
fn lint_explicit_closure(cx: &LateContext<'_>, replace: Span, root: Span, is_copy: bool, msrv: &Msrv) {
let mut applicability = Applicability::MachineApplicable;
let (message, sugg_method) = if is_copy && msrv.meets(msrvs::ITERATOR_COPIED) {
("you are using an explicit closure for copying elements", "copied")
} else {
("you are using an explicit closure for cloning elements", "cloned")
};
span_lint_and_sugg(
cx,
MAP_CLONE,
replace,
message,
&format!("consider calling the dedicated `{sugg_method}` method"),
format!(
"{}.{sugg_method}()",
snippet_with_applicability(cx, root, "..", &mut applicability),
),
applicability,
);
}
|
