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
use std::ops::{Deref, DerefMut};
use Resolver;
use resolve_imports::ImportDirectiveSubclass;
use rustc::{lint, ty};
use rustc::util::nodemap::NodeMap;
use syntax::ast::{self, ViewPathGlob, ViewPathList, ViewPathSimple};
use syntax::visit::{self, Visitor};
use syntax_pos::{Span, MultiSpan, DUMMY_SP};
struct UnusedImportCheckVisitor<'a, 'b: 'a> {
resolver: &'a mut Resolver<'b>,
unused_imports: NodeMap<NodeMap<Span>>,
}
impl<'a, 'b> Deref for UnusedImportCheckVisitor<'a, 'b> {
type Target = Resolver<'b>;
fn deref<'c>(&'c self) -> &'c Resolver<'b> {
&*self.resolver
}
}
impl<'a, 'b> DerefMut for UnusedImportCheckVisitor<'a, 'b> {
fn deref_mut<'c>(&'c mut self) -> &'c mut Resolver<'b> {
&mut *self.resolver
}
}
impl<'a, 'b> UnusedImportCheckVisitor<'a, 'b> {
fn check_import(&mut self, item_id: ast::NodeId, id: ast::NodeId, span: Span) {
let mut used = false;
self.per_ns(|this, ns| used |= this.used_imports.contains(&(id, ns)));
if !used {
if self.maybe_unused_trait_imports.contains(&id) {
return;
}
self.unused_imports.entry(item_id).or_insert_with(NodeMap).insert(id, span);
} else {
self.maybe_unused_trait_imports.remove(&id);
if let Some(i) = self.unused_imports.get_mut(&item_id) {
i.remove(&id);
}
}
}
}
impl<'a, 'b> Visitor<'a> for UnusedImportCheckVisitor<'a, 'b> {
fn visit_item(&mut self, item: &'a ast::Item) {
visit::walk_item(self, item);
if item.vis == ast::Visibility::Public || item.span.source_equal(&DUMMY_SP) {
return;
}
match item.node {
ast::ItemKind::Use(ref p) => {
match p.node {
ViewPathSimple(..) => {
self.check_import(item.id, item.id, p.span)
}
ViewPathList(_, ref list) => {
if list.len() == 0 {
self.unused_imports
.entry(item.id)
.or_insert_with(NodeMap)
.insert(item.id, item.span);
}
for i in list {
self.check_import(item.id, i.node.id, i.span);
}
}
ViewPathGlob(_) => {
self.check_import(item.id, item.id, p.span);
}
}
}
_ => {}
}
}
}
pub fn check_crate(resolver: &mut Resolver, krate: &ast::Crate) {
for directive in resolver.potentially_unused_imports.iter() {
match directive.subclass {
_ if directive.used.get() ||
directive.vis.get() == ty::Visibility::Public ||
directive.span.source_equal(&DUMMY_SP) => {}
ImportDirectiveSubclass::ExternCrate => {
let lint = lint::builtin::UNUSED_EXTERN_CRATES;
let msg = "unused extern crate".to_string();
resolver.session.add_lint(lint, directive.id, directive.span, msg);
}
ImportDirectiveSubclass::MacroUse => {
let lint = lint::builtin::UNUSED_IMPORTS;
let msg = "unused `#[macro_use]` import".to_string();
resolver.session.add_lint(lint, directive.id, directive.span, msg);
}
_ => {}
}
}
let mut visitor = UnusedImportCheckVisitor {
resolver: resolver,
unused_imports: NodeMap(),
};
visit::walk_crate(&mut visitor, krate);
for (id, spans) in &visitor.unused_imports {
let len = spans.len();
let mut spans = spans.values().map(|s| *s).collect::<Vec<Span>>();
spans.sort();
let ms = MultiSpan::from_spans(spans.clone());
let mut span_snippets = spans.iter()
.filter_map(|s| {
match visitor.session.codemap().span_to_snippet(*s) {
Ok(s) => Some(format!("`{}`", s)),
_ => None,
}
}).collect::<Vec<String>>();
span_snippets.sort();
let msg = format!("unused import{}{}",
if len > 1 { "s" } else { "" },
if span_snippets.len() > 0 {
format!(": {}", span_snippets.join(", "))
} else {
String::new()
});
visitor.session.add_lint(lint::builtin::UNUSED_IMPORTS,
*id,
ms,
msg);
}
}