1 use clippy_utils::diagnostics::{span_lint_and_help, span_lint_and_sugg};
2 use rustc_ast::{ptr::P, Crate, Item, ItemKind, MacroDef, ModKind, UseTreeKind};
3 use rustc_errors::Applicability;
4 use rustc_lint::{EarlyContext, EarlyLintPass, LintContext};
5 use rustc_session::{declare_lint_pass, declare_tool_lint};
6 use rustc_span::{edition::Edition, symbol::kw, Span, Symbol};
10 /// Checking for imports with single component use path.
12 /// ### Why is this bad?
13 /// Import with single component use path such as `use cratename;`
14 /// is not necessary, and thus should be removed.
21 /// regex::Regex::new(r"^\d{4}-\d{2}-\d{2}$").unwrap();
27 /// regex::Regex::new(r"^\d{4}-\d{2}-\d{2}$").unwrap();
30 #[clippy::version = "1.43.0"]
31 pub SINGLE_COMPONENT_PATH_IMPORTS,
33 "imports with single component path are redundant"
36 declare_lint_pass!(SingleComponentPathImports => [SINGLE_COMPONENT_PATH_IMPORTS]);
38 impl EarlyLintPass for SingleComponentPathImports {
39 fn check_crate(&mut self, cx: &EarlyContext<'_>, krate: &Crate) {
40 if cx.sess().opts.edition < Edition::Edition2018 {
43 check_mod(cx, &krate.items);
47 fn check_mod(cx: &EarlyContext<'_>, items: &[P<Item>]) {
48 // keep track of imports reused with `self` keyword,
49 // such as `self::crypto_hash` in the example below
51 // use self::crypto_hash::{Algorithm, Hasher};
53 let mut imports_reused_with_self = Vec::new();
55 // keep track of single use statements
56 // such as `crypto_hash` in the example below
60 let mut single_use_usages = Vec::new();
62 // keep track of macros defined in the module as we don't want it to trigger on this (#7106)
64 // macro_rules! foo { () => {} };
65 // pub(crate) use foo;
67 let mut macros = Vec::new();
73 &mut imports_reused_with_self,
74 &mut single_use_usages,
79 for (name, span, can_suggest) in single_use_usages {
80 if !imports_reused_with_self.contains(&name) {
84 SINGLE_COMPONENT_PATH_IMPORTS,
86 "this import is redundant",
89 Applicability::MachineApplicable,
94 SINGLE_COMPONENT_PATH_IMPORTS,
96 "this import is redundant",
106 cx: &EarlyContext<'_>,
108 imports_reused_with_self: &mut Vec<Symbol>,
109 single_use_usages: &mut Vec<(Symbol, Span, bool)>,
110 macros: &mut Vec<Symbol>,
112 if item.span.from_expansion() || item.vis.kind.is_pub() {
117 ItemKind::Mod(_, ModKind::Loaded(ref items, ..)) => {
118 check_mod(cx, items);
120 ItemKind::MacroDef(MacroDef { macro_rules: true, .. }) => {
121 macros.push(item.ident.name);
123 ItemKind::Use(use_tree) => {
124 let segments = &use_tree.prefix.segments;
126 // keep track of `use some_module;` usages
127 if segments.len() == 1 {
128 if let UseTreeKind::Simple(None, _, _) = use_tree.kind {
129 let name = segments[0].ident.name;
130 if !macros.contains(&name) {
131 single_use_usages.push((name, item.span, true));
137 if segments.is_empty() {
138 // keep track of `use {some_module, some_other_module};` usages
139 if let UseTreeKind::Nested(trees) = &use_tree.kind {
141 let segments = &tree.0.prefix.segments;
142 if segments.len() == 1 {
143 if let UseTreeKind::Simple(None, _, _) = tree.0.kind {
144 let name = segments[0].ident.name;
145 if !macros.contains(&name) {
146 single_use_usages.push((name, tree.0.span, false));
153 // keep track of `use self::some_module` usages
154 if segments[0].ident.name == kw::SelfLower {
155 // simple case such as `use self::module::SomeStruct`
156 if segments.len() > 1 {
157 imports_reused_with_self.push(segments[1].ident.name);
161 // nested case such as `use self::{module1::Struct1, module2::Struct2}`
162 if let UseTreeKind::Nested(trees) = &use_tree.kind {
164 let segments = &tree.0.prefix.segments;
165 if !segments.is_empty() {
166 imports_reused_with_self.push(segments[0].ident.name);