1 use if_chain::if_chain;
2 use rustc::hir::def::{CtorKind, Def};
3 use rustc::hir::intravisit::{walk_item, walk_path, walk_ty, NestedVisitorMap, Visitor};
5 use rustc::lint::{in_external_macro, LateContext, LateLintPass, LintArray, LintContext, LintPass};
7 use rustc::ty::DefIdTree;
8 use rustc::{declare_lint_pass, declare_tool_lint};
9 use rustc_errors::Applicability;
10 use syntax_pos::symbol::keywords::SelfUpper;
12 use crate::utils::span_lint_and_sugg;
14 declare_clippy_lint! {
15 /// **What it does:** Checks for unnecessary repetition of structure name when a
16 /// replacement with `Self` is applicable.
18 /// **Why is this bad?** Unnecessary repetition. Mixed use of `Self` and struct
20 /// feels inconsistent.
22 /// **Known problems:**
23 /// - False positive when using associated types (#2843)
24 /// - False positives in some situations when using generics (#3410)
39 /// fn new() -> Self {
46 "Unnecessary structure name repetition whereas `Self` is applicable"
49 declare_lint_pass!(UseSelf => [USE_SELF]);
51 const SEGMENTS_MSG: &str = "segments should be composed of at least 1 element";
53 fn span_use_self_lint(cx: &LateContext<'_, '_>, path: &Path) {
54 // Path segments only include actual path, no methods or fields.
55 let last_path_span = path.segments.last().expect(SEGMENTS_MSG).ident.span;
56 // Only take path up to the end of last_path_span.
57 let span = path.span.with_hi(last_path_span.hi());
63 "unnecessary structure name repetition",
64 "use the applicable keyword",
66 Applicability::MachineApplicable,
70 struct TraitImplTyVisitor<'a, 'tcx: 'a> {
71 item_type: ty::Ty<'tcx>,
72 cx: &'a LateContext<'a, 'tcx>,
73 trait_type_walker: ty::walk::TypeWalker<'tcx>,
74 impl_type_walker: ty::walk::TypeWalker<'tcx>,
77 impl<'a, 'tcx> Visitor<'tcx> for TraitImplTyVisitor<'a, 'tcx> {
78 fn visit_ty(&mut self, t: &'tcx Ty) {
79 let trait_ty = self.trait_type_walker.next();
80 let impl_ty = self.impl_type_walker.next();
82 if let TyKind::Path(QPath::Resolved(_, path)) = &t.node {
83 // The implementation and trait types don't match which means that
84 // the concrete type was specified by the implementation
85 if impl_ty != trait_ty {
86 if let Some(impl_ty) = impl_ty {
87 if self.item_type == impl_ty {
88 let is_self_ty = if let def::Def::SelfTy(..) = path.def {
95 span_use_self_lint(self.cx, path);
105 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
106 NestedVisitorMap::None
110 fn check_trait_method_impl_decl<'a, 'tcx: 'a>(
111 cx: &'a LateContext<'a, 'tcx>,
112 item_type: ty::Ty<'tcx>,
113 impl_item: &ImplItem,
114 impl_decl: &'tcx FnDecl,
115 impl_trait_ref: &ty::TraitRef<'_>,
117 let trait_method = cx
119 .associated_items(impl_trait_ref.def_id)
121 assoc_item.kind == ty::AssociatedKind::Method
124 .hygienic_eq(impl_item.ident, assoc_item.ident, impl_trait_ref.def_id)
126 .expect("impl method matches a trait method");
128 let trait_method_sig = cx.tcx.fn_sig(trait_method.def_id);
129 let trait_method_sig = cx.tcx.erase_late_bound_regions(&trait_method_sig);
131 let impl_method_def_id = cx.tcx.hir().local_def_id_from_hir_id(impl_item.hir_id);
132 let impl_method_sig = cx.tcx.fn_sig(impl_method_def_id);
133 let impl_method_sig = cx.tcx.erase_late_bound_regions(&impl_method_sig);
135 let output_ty = if let FunctionRetTy::Return(ty) = &impl_decl.output {
141 // `impl_decl_ty` (of type `hir::Ty`) represents the type declared in the signature.
142 // `impl_ty` (of type `ty:TyS`) is the concrete type that the compiler has determined for
143 // that declaration. We use `impl_decl_ty` to see if the type was declared as `Self`
144 // and use `impl_ty` to check its concrete type.
145 for (impl_decl_ty, (impl_ty, trait_ty)) in impl_decl.inputs.iter().chain(output_ty).zip(
149 .zip(trait_method_sig.inputs_and_output),
151 let mut visitor = TraitImplTyVisitor {
154 trait_type_walker: trait_ty.walk(),
155 impl_type_walker: impl_ty.walk(),
158 visitor.visit_ty(&impl_decl_ty);
162 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UseSelf {
163 fn check_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx Item) {
164 if in_external_macro(cx.sess(), item.span) {
168 if let ItemKind::Impl(.., ref item_type, ref refs) = item.node;
169 if let TyKind::Path(QPath::Resolved(_, ref item_path)) = item_type.node;
171 let parameters = &item_path.segments.last().expect(SEGMENTS_MSG).args;
172 let should_check = if let Some(ref params) = *parameters {
173 !params.parenthesized && !params.args.iter().any(|arg| match arg {
174 GenericArg::Lifetime(_) => true,
182 let visitor = &mut UseSelfVisitor {
186 let impl_def_id = cx.tcx.hir().local_def_id_from_hir_id(item.hir_id);
187 let impl_trait_ref = cx.tcx.impl_trait_ref(impl_def_id);
189 if let Some(impl_trait_ref) = impl_trait_ref {
190 for impl_item_ref in refs {
191 let impl_item = cx.tcx.hir().impl_item(impl_item_ref.id);
192 if let ImplItemKind::Method(MethodSig{ decl: impl_decl, .. }, impl_body_id)
194 let item_type = cx.tcx.type_of(impl_def_id);
195 check_trait_method_impl_decl(cx, item_type, impl_item, impl_decl, &impl_trait_ref);
197 let body = cx.tcx.hir().body(*impl_body_id);
198 visitor.visit_body(body);
200 visitor.visit_impl_item(impl_item);
204 for impl_item_ref in refs {
205 let impl_item = cx.tcx.hir().impl_item(impl_item_ref.id);
206 visitor.visit_impl_item(impl_item);
215 struct UseSelfVisitor<'a, 'tcx: 'a> {
217 cx: &'a LateContext<'a, 'tcx>,
220 impl<'a, 'tcx> Visitor<'tcx> for UseSelfVisitor<'a, 'tcx> {
221 fn visit_path(&mut self, path: &'tcx Path, _id: HirId) {
222 if path.segments.last().expect(SEGMENTS_MSG).ident.name != SelfUpper.name() {
223 if self.item_path.def == path.def {
224 span_use_self_lint(self.cx, path);
225 } else if let Def::Ctor(ctor_did, def::CtorOf::Struct, CtorKind::Fn) = path.def {
226 if self.item_path.def.opt_def_id() == self.cx.tcx.parent(ctor_did) {
227 span_use_self_lint(self.cx, path);
231 walk_path(self, path);
234 fn visit_item(&mut self, item: &'tcx Item) {
237 | ItemKind::Static(..)
239 | ItemKind::Struct(..)
240 | ItemKind::Union(..)
242 | ItemKind::Fn(..) => {
243 // Don't check statements that shadow `Self` or where `Self` can't be used
245 _ => walk_item(self, item),
249 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
250 NestedVisitorMap::All(&self.cx.tcx.hir())