1 use if_chain::if_chain;
2 use rustc::declare_lint_pass;
4 use rustc::hir::def::{DefKind, Res};
5 use rustc::hir::intravisit::{walk_item, walk_path, walk_ty, NestedVisitorMap, Visitor};
7 use rustc::lint::{in_external_macro, LateContext, LateLintPass, LintArray, LintContext, LintPass};
9 use rustc::ty::{DefIdTree, Ty};
10 use rustc_errors::Applicability;
11 use rustc_session::declare_tool_lint;
12 use syntax_pos::symbol::kw;
14 use crate::utils::{differing_macro_contexts, span_lint_and_sugg};
16 declare_clippy_lint! {
17 /// **What it does:** Checks for unnecessary repetition of structure name when a
18 /// replacement with `Self` is applicable.
20 /// **Why is this bad?** Unnecessary repetition. Mixed use of `Self` and struct
22 /// feels inconsistent.
24 /// **Known problems:**
25 /// - False positive when using associated types (#2843)
26 /// - False positives in some situations when using generics (#3410)
41 /// fn new() -> Self {
48 "Unnecessary structure name repetition whereas `Self` is applicable"
51 declare_lint_pass!(UseSelf => [USE_SELF]);
53 const SEGMENTS_MSG: &str = "segments should be composed of at least 1 element";
55 fn span_use_self_lint(cx: &LateContext<'_, '_>, path: &Path, last_segment: Option<&PathSegment>) {
56 let last_segment = last_segment.unwrap_or_else(|| path.segments.last().expect(SEGMENTS_MSG));
58 // Path segments only include actual path, no methods or fields.
59 let last_path_span = last_segment.ident.span;
61 if differing_macro_contexts(path.span, last_path_span) {
65 // Only take path up to the end of last_path_span.
66 let span = path.span.with_hi(last_path_span.hi());
72 "unnecessary structure name repetition",
73 "use the applicable keyword",
75 Applicability::MachineApplicable,
79 struct TraitImplTyVisitor<'a, 'tcx> {
81 cx: &'a LateContext<'a, 'tcx>,
82 trait_type_walker: ty::walk::TypeWalker<'tcx>,
83 impl_type_walker: ty::walk::TypeWalker<'tcx>,
86 impl<'a, 'tcx> Visitor<'tcx> for TraitImplTyVisitor<'a, 'tcx> {
87 fn visit_ty(&mut self, t: &'tcx hir::Ty) {
88 let trait_ty = self.trait_type_walker.next();
89 let impl_ty = self.impl_type_walker.next();
92 if let TyKind::Path(QPath::Resolved(_, path)) = &t.kind;
94 // The implementation and trait types don't match which means that
95 // the concrete type was specified by the implementation
96 if impl_ty != trait_ty;
97 if let Some(impl_ty) = impl_ty;
98 if self.item_type == impl_ty;
101 def::Res::SelfTy(..) => {},
102 _ => span_use_self_lint(self.cx, path, None)
110 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
111 NestedVisitorMap::None
115 fn check_trait_method_impl_decl<'a, 'tcx>(
116 cx: &'a LateContext<'a, 'tcx>,
118 impl_item: &ImplItem,
119 impl_decl: &'tcx FnDecl,
120 impl_trait_ref: &ty::TraitRef<'_>,
122 let trait_method = cx
124 .associated_items(impl_trait_ref.def_id)
126 assoc_item.kind == ty::AssocKind::Method
129 .hygienic_eq(impl_item.ident, assoc_item.ident, impl_trait_ref.def_id)
131 .expect("impl method matches a trait method");
133 let trait_method_sig = cx.tcx.fn_sig(trait_method.def_id);
134 let trait_method_sig = cx.tcx.erase_late_bound_regions(&trait_method_sig);
136 let impl_method_def_id = cx.tcx.hir().local_def_id(impl_item.hir_id);
137 let impl_method_sig = cx.tcx.fn_sig(impl_method_def_id);
138 let impl_method_sig = cx.tcx.erase_late_bound_regions(&impl_method_sig);
140 let output_ty = if let FunctionRetTy::Return(ty) = &impl_decl.output {
146 // `impl_decl_ty` (of type `hir::Ty`) represents the type declared in the signature.
147 // `impl_ty` (of type `ty:TyS`) is the concrete type that the compiler has determined for
148 // that declaration. We use `impl_decl_ty` to see if the type was declared as `Self`
149 // and use `impl_ty` to check its concrete type.
150 for (impl_decl_ty, (impl_ty, trait_ty)) in impl_decl.inputs.iter().chain(output_ty).zip(
154 .zip(trait_method_sig.inputs_and_output),
156 let mut visitor = TraitImplTyVisitor {
159 trait_type_walker: trait_ty.walk(),
160 impl_type_walker: impl_ty.walk(),
163 visitor.visit_ty(&impl_decl_ty);
167 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UseSelf {
168 fn check_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx Item) {
169 if in_external_macro(cx.sess(), item.span) {
173 if let ItemKind::Impl(.., ref item_type, ref refs) = item.kind;
174 if let TyKind::Path(QPath::Resolved(_, ref item_path)) = item_type.kind;
176 let parameters = &item_path.segments.last().expect(SEGMENTS_MSG).args;
177 let should_check = if let Some(ref params) = *parameters {
178 !params.parenthesized && !params.args.iter().any(|arg| match arg {
179 GenericArg::Lifetime(_) => true,
187 let visitor = &mut UseSelfVisitor {
191 let impl_def_id = cx.tcx.hir().local_def_id(item.hir_id);
192 let impl_trait_ref = cx.tcx.impl_trait_ref(impl_def_id);
194 if let Some(impl_trait_ref) = impl_trait_ref {
195 for impl_item_ref in refs {
196 let impl_item = cx.tcx.hir().impl_item(impl_item_ref.id);
197 if let ImplItemKind::Method(FnSig{ decl: impl_decl, .. }, impl_body_id)
199 let item_type = cx.tcx.type_of(impl_def_id);
200 check_trait_method_impl_decl(cx, item_type, impl_item, impl_decl, &impl_trait_ref);
202 let body = cx.tcx.hir().body(*impl_body_id);
203 visitor.visit_body(body);
205 visitor.visit_impl_item(impl_item);
209 for impl_item_ref in refs {
210 let impl_item = cx.tcx.hir().impl_item(impl_item_ref.id);
211 visitor.visit_impl_item(impl_item);
220 struct UseSelfVisitor<'a, 'tcx> {
222 cx: &'a LateContext<'a, 'tcx>,
225 impl<'a, 'tcx> Visitor<'tcx> for UseSelfVisitor<'a, 'tcx> {
226 fn visit_path(&mut self, path: &'tcx Path, _id: HirId) {
227 if !path.segments.iter().any(|p| p.ident.span.is_dummy()) {
228 if path.segments.len() >= 2 {
229 let last_but_one = &path.segments[path.segments.len() - 2];
230 if last_but_one.ident.name != kw::SelfUpper {
231 let enum_def_id = match path.res {
232 Res::Def(DefKind::Variant, variant_def_id) => self.cx.tcx.parent(variant_def_id),
233 Res::Def(DefKind::Ctor(def::CtorOf::Variant, _), ctor_def_id) => {
234 let variant_def_id = self.cx.tcx.parent(ctor_def_id);
235 variant_def_id.and_then(|def_id| self.cx.tcx.parent(def_id))
240 if self.item_path.res.opt_def_id() == enum_def_id {
241 span_use_self_lint(self.cx, path, Some(last_but_one));
246 if path.segments.last().expect(SEGMENTS_MSG).ident.name != kw::SelfUpper {
247 if self.item_path.res == path.res {
248 span_use_self_lint(self.cx, path, None);
249 } else if let Res::Def(DefKind::Ctor(def::CtorOf::Struct, _), ctor_def_id) = path.res {
250 if self.item_path.res.opt_def_id() == self.cx.tcx.parent(ctor_def_id) {
251 span_use_self_lint(self.cx, path, None);
257 walk_path(self, path);
260 fn visit_item(&mut self, item: &'tcx Item) {
263 | ItemKind::Static(..)
265 | ItemKind::Struct(..)
266 | ItemKind::Union(..)
268 | ItemKind::Fn(..) => {
269 // Don't check statements that shadow `Self` or where `Self` can't be used
271 _ => walk_item(self, item),
275 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
276 NestedVisitorMap::All(&self.cx.tcx.hir())