1 use if_chain::if_chain;
2 use rustc::hir::map::Map;
3 use rustc::lint::in_external_macro;
5 use rustc::ty::{DefIdTree, Ty};
6 use rustc_errors::Applicability;
8 use rustc_hir::def::{DefKind, Res};
9 use rustc_hir::intravisit::{walk_item, walk_path, walk_ty, NestedVisitorMap, Visitor};
11 use rustc_lint::{LateContext, LateLintPass, LintContext};
12 use rustc_session::{declare_lint_pass, declare_tool_lint};
13 use rustc_span::symbol::kw;
15 use crate::utils::{differing_macro_contexts, span_lint_and_sugg};
17 declare_clippy_lint! {
18 /// **What it does:** Checks for unnecessary repetition of structure name when a
19 /// replacement with `Self` is applicable.
21 /// **Why is this bad?** Unnecessary repetition. Mixed use of `Self` and struct
23 /// feels inconsistent.
25 /// **Known problems:**
26 /// - False positive when using associated types (#2843)
27 /// - False positives in some situations when using generics (#3410)
42 /// fn new() -> Self {
49 "Unnecessary structure name repetition whereas `Self` is applicable"
52 declare_lint_pass!(UseSelf => [USE_SELF]);
54 const SEGMENTS_MSG: &str = "segments should be composed of at least 1 element";
56 fn span_use_self_lint(cx: &LateContext<'_, '_>, path: &Path<'_>, last_segment: Option<&PathSegment<'_>>) {
57 let last_segment = last_segment.unwrap_or_else(|| path.segments.last().expect(SEGMENTS_MSG));
59 // Path segments only include actual path, no methods or fields.
60 let last_path_span = last_segment.ident.span;
62 if differing_macro_contexts(path.span, last_path_span) {
66 // Only take path up to the end of last_path_span.
67 let span = path.span.with_hi(last_path_span.hi());
73 "unnecessary structure name repetition",
74 "use the applicable keyword",
76 Applicability::MachineApplicable,
80 struct TraitImplTyVisitor<'a, 'tcx> {
82 cx: &'a LateContext<'a, 'tcx>,
83 trait_type_walker: ty::walk::TypeWalker<'tcx>,
84 impl_type_walker: ty::walk::TypeWalker<'tcx>,
87 impl<'a, 'tcx> Visitor<'tcx> for TraitImplTyVisitor<'a, 'tcx> {
90 fn visit_ty(&mut self, t: &'tcx hir::Ty<'_>) {
91 let trait_ty = self.trait_type_walker.next();
92 let impl_ty = self.impl_type_walker.next();
95 if let TyKind::Path(QPath::Resolved(_, path)) = &t.kind;
97 // The implementation and trait types don't match which means that
98 // the concrete type was specified by the implementation
99 if impl_ty != trait_ty;
100 if let Some(impl_ty) = impl_ty;
101 if self.item_type == impl_ty;
104 def::Res::SelfTy(..) => {},
105 _ => span_use_self_lint(self.cx, path, None)
113 fn nested_visit_map(&mut self) -> NestedVisitorMap<'_, Self::Map> {
114 NestedVisitorMap::None
118 fn check_trait_method_impl_decl<'a, 'tcx>(
119 cx: &'a LateContext<'a, 'tcx>,
121 impl_item: &ImplItem<'_>,
122 impl_decl: &'tcx FnDecl<'_>,
123 impl_trait_ref: &ty::TraitRef<'_>,
125 let trait_method = cx
127 .associated_items(impl_trait_ref.def_id)
129 assoc_item.kind == ty::AssocKind::Method
132 .hygienic_eq(impl_item.ident, assoc_item.ident, impl_trait_ref.def_id)
134 .expect("impl method matches a trait method");
136 let trait_method_sig = cx.tcx.fn_sig(trait_method.def_id);
137 let trait_method_sig = cx.tcx.erase_late_bound_regions(&trait_method_sig);
139 let impl_method_def_id = cx.tcx.hir().local_def_id(impl_item.hir_id);
140 let impl_method_sig = cx.tcx.fn_sig(impl_method_def_id);
141 let impl_method_sig = cx.tcx.erase_late_bound_regions(&impl_method_sig);
143 let output_ty = if let FunctionRetTy::Return(ty) = &impl_decl.output {
149 // `impl_decl_ty` (of type `hir::Ty`) represents the type declared in the signature.
150 // `impl_ty` (of type `ty:TyS`) is the concrete type that the compiler has determined for
151 // that declaration. We use `impl_decl_ty` to see if the type was declared as `Self`
152 // and use `impl_ty` to check its concrete type.
153 for (impl_decl_ty, (impl_ty, trait_ty)) in impl_decl.inputs.iter().chain(output_ty).zip(
157 .zip(trait_method_sig.inputs_and_output),
159 let mut visitor = TraitImplTyVisitor {
162 trait_type_walker: trait_ty.walk(),
163 impl_type_walker: impl_ty.walk(),
166 visitor.visit_ty(&impl_decl_ty);
170 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UseSelf {
171 fn check_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx Item<'_>) {
172 if in_external_macro(cx.sess(), item.span) {
176 if let ItemKind::Impl(.., ref item_type, refs) = item.kind;
177 if let TyKind::Path(QPath::Resolved(_, ref item_path)) = item_type.kind;
179 let parameters = &item_path.segments.last().expect(SEGMENTS_MSG).args;
180 let should_check = if let Some(ref params) = *parameters {
181 !params.parenthesized && !params.args.iter().any(|arg| match arg {
182 GenericArg::Lifetime(_) => true,
190 let visitor = &mut UseSelfVisitor {
194 let impl_def_id = cx.tcx.hir().local_def_id(item.hir_id);
195 let impl_trait_ref = cx.tcx.impl_trait_ref(impl_def_id);
197 if let Some(impl_trait_ref) = impl_trait_ref {
198 for impl_item_ref in refs {
199 let impl_item = cx.tcx.hir().impl_item(impl_item_ref.id);
200 if let ImplItemKind::Method(FnSig{ decl: impl_decl, .. }, impl_body_id)
202 let item_type = cx.tcx.type_of(impl_def_id);
203 check_trait_method_impl_decl(cx, item_type, impl_item, impl_decl, &impl_trait_ref);
205 let body = cx.tcx.hir().body(*impl_body_id);
206 visitor.visit_body(body);
208 visitor.visit_impl_item(impl_item);
212 for impl_item_ref in refs {
213 let impl_item = cx.tcx.hir().impl_item(impl_item_ref.id);
214 visitor.visit_impl_item(impl_item);
223 struct UseSelfVisitor<'a, 'tcx> {
224 item_path: &'a Path<'a>,
225 cx: &'a LateContext<'a, 'tcx>,
228 impl<'a, 'tcx> Visitor<'tcx> for UseSelfVisitor<'a, 'tcx> {
229 type Map = Map<'tcx>;
231 fn visit_path(&mut self, path: &'tcx Path<'_>, _id: HirId) {
232 if !path.segments.iter().any(|p| p.ident.span.is_dummy()) {
233 if path.segments.len() >= 2 {
234 let last_but_one = &path.segments[path.segments.len() - 2];
235 if last_but_one.ident.name != kw::SelfUpper {
236 let enum_def_id = match path.res {
237 Res::Def(DefKind::Variant, variant_def_id) => self.cx.tcx.parent(variant_def_id),
238 Res::Def(DefKind::Ctor(def::CtorOf::Variant, _), ctor_def_id) => {
239 let variant_def_id = self.cx.tcx.parent(ctor_def_id);
240 variant_def_id.and_then(|def_id| self.cx.tcx.parent(def_id))
245 if self.item_path.res.opt_def_id() == enum_def_id {
246 span_use_self_lint(self.cx, path, Some(last_but_one));
251 if path.segments.last().expect(SEGMENTS_MSG).ident.name != kw::SelfUpper {
252 if self.item_path.res == path.res {
253 span_use_self_lint(self.cx, path, None);
254 } else if let Res::Def(DefKind::Ctor(def::CtorOf::Struct, _), ctor_def_id) = path.res {
255 if self.item_path.res.opt_def_id() == self.cx.tcx.parent(ctor_def_id) {
256 span_use_self_lint(self.cx, path, None);
262 walk_path(self, path);
265 fn visit_item(&mut self, item: &'tcx Item<'_>) {
268 | ItemKind::Static(..)
270 | ItemKind::Struct(..)
271 | ItemKind::Union(..)
273 | ItemKind::Fn(..) => {
274 // Don't check statements that shadow `Self` or where `Self` can't be used
276 _ => walk_item(self, item),
280 fn nested_visit_map(&mut self) -> NestedVisitorMap<'_, Self::Map> {
281 NestedVisitorMap::All(&self.cx.tcx.hir())