mirror of
https://github.com/rust-lang/rust-clippy
synced 2024-12-22 19:13:29 +00:00
252 lines
8.6 KiB
Rust
252 lines
8.6 KiB
Rust
// Copyright 2014-2018 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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use crate::utils::span_lint_and_sugg;
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use if_chain::if_chain;
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use rustc::hir::def::{CtorKind, Def};
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use rustc::hir::intravisit::{walk_path, walk_ty, NestedVisitorMap, Visitor};
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use rustc::hir::*;
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use rustc::lint::{in_external_macro, LateContext, LateLintPass, LintArray, LintContext, LintPass};
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use rustc::ty;
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use rustc::{declare_tool_lint, lint_array};
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use rustc_errors::Applicability;
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use syntax::ast::NodeId;
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use syntax_pos::symbol::keywords::SelfUpper;
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/// **What it does:** Checks for unnecessary repetition of structure name when a
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/// replacement with `Self` is applicable.
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///
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/// **Why is this bad?** Unnecessary repetition. Mixed use of `Self` and struct
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/// name
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/// feels inconsistent.
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///
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/// **Known problems:**
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/// - False positive when using associated types (#2843)
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/// - False positives in some situations when using generics (#3410)
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/// - False positive when type from outer function can't be used (#3463)
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///
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/// **Example:**
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/// ```rust
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/// struct Foo {}
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/// impl Foo {
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/// fn new() -> Foo {
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/// Foo {}
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/// }
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/// }
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/// ```
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/// could be
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/// ```rust
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/// struct Foo {}
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/// impl Foo {
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/// fn new() -> Self {
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/// Self {}
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/// }
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/// }
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/// ```
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declare_clippy_lint! {
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pub USE_SELF,
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pedantic,
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"Unnecessary structure name repetition whereas `Self` is applicable"
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}
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#[derive(Copy, Clone, Default)]
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pub struct UseSelf;
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impl LintPass for UseSelf {
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fn get_lints(&self) -> LintArray {
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lint_array!(USE_SELF)
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}
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}
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const SEGMENTS_MSG: &str = "segments should be composed of at least 1 element";
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fn span_use_self_lint(cx: &LateContext<'_, '_>, path: &Path) {
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span_lint_and_sugg(
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cx,
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USE_SELF,
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path.span,
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"unnecessary structure name repetition",
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"use the applicable keyword",
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"Self".to_owned(),
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Applicability::MachineApplicable,
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);
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}
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struct TraitImplTyVisitor<'a, 'tcx: 'a> {
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item_type: ty::Ty<'tcx>,
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cx: &'a LateContext<'a, 'tcx>,
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trait_type_walker: ty::walk::TypeWalker<'tcx>,
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impl_type_walker: ty::walk::TypeWalker<'tcx>,
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}
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impl<'a, 'tcx> Visitor<'tcx> for TraitImplTyVisitor<'a, 'tcx> {
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fn visit_ty(&mut self, t: &'tcx Ty) {
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let trait_ty = self.trait_type_walker.next();
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let impl_ty = self.impl_type_walker.next();
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if let TyKind::Path(QPath::Resolved(_, path)) = &t.node {
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// The implementation and trait types don't match which means that
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// the concrete type was specified by the implementation
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if impl_ty != trait_ty {
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if let Some(impl_ty) = impl_ty {
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if self.item_type == impl_ty {
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let is_self_ty = if let def::Def::SelfTy(..) = path.def {
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true
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} else {
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false
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};
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if !is_self_ty {
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span_use_self_lint(self.cx, path);
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}
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}
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}
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}
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}
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walk_ty(self, t)
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}
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fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
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NestedVisitorMap::None
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}
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}
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fn check_trait_method_impl_decl<'a, 'tcx: 'a>(
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cx: &'a LateContext<'a, 'tcx>,
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item_type: ty::Ty<'tcx>,
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impl_item: &ImplItem,
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impl_decl: &'tcx FnDecl,
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impl_trait_ref: &ty::TraitRef<'_>,
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) {
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let trait_method = cx
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.tcx
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.associated_items(impl_trait_ref.def_id)
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.find(|assoc_item| {
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assoc_item.kind == ty::AssociatedKind::Method
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&& cx
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.tcx
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.hygienic_eq(impl_item.ident, assoc_item.ident, impl_trait_ref.def_id)
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})
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.expect("impl method matches a trait method");
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let trait_method_sig = cx.tcx.fn_sig(trait_method.def_id);
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let trait_method_sig = cx.tcx.erase_late_bound_regions(&trait_method_sig);
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let impl_method_def_id = cx.tcx.hir().local_def_id(impl_item.id);
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let impl_method_sig = cx.tcx.fn_sig(impl_method_def_id);
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let impl_method_sig = cx.tcx.erase_late_bound_regions(&impl_method_sig);
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let output_ty = if let FunctionRetTy::Return(ty) = &impl_decl.output {
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Some(&**ty)
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} else {
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None
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};
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// `impl_decl_ty` (of type `hir::Ty`) represents the type declared in the signature.
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// `impl_ty` (of type `ty:TyS`) is the concrete type that the compiler has determined for
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// that declaration. We use `impl_decl_ty` to see if the type was declared as `Self`
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// and use `impl_ty` to check its concrete type.
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for (impl_decl_ty, (impl_ty, trait_ty)) in impl_decl.inputs.iter().chain(output_ty).zip(
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impl_method_sig
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.inputs_and_output
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.iter()
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.zip(trait_method_sig.inputs_and_output),
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) {
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let mut visitor = TraitImplTyVisitor {
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cx,
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item_type,
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trait_type_walker: trait_ty.walk(),
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impl_type_walker: impl_ty.walk(),
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};
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visitor.visit_ty(&impl_decl_ty);
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}
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}
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impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UseSelf {
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fn check_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx Item) {
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if in_external_macro(cx.sess(), item.span) {
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return;
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}
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if_chain! {
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if let ItemKind::Impl(.., ref item_type, ref refs) = item.node;
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if let TyKind::Path(QPath::Resolved(_, ref item_path)) = item_type.node;
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then {
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let parameters = &item_path.segments.last().expect(SEGMENTS_MSG).args;
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let should_check = if let Some(ref params) = *parameters {
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!params.parenthesized && !params.args.iter().any(|arg| match arg {
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GenericArg::Lifetime(_) => true,
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GenericArg::Type(_) => false,
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})
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} else {
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true
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};
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if should_check {
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let visitor = &mut UseSelfVisitor {
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item_path,
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cx,
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};
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let impl_def_id = cx.tcx.hir().local_def_id(item.id);
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let impl_trait_ref = cx.tcx.impl_trait_ref(impl_def_id);
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if let Some(impl_trait_ref) = impl_trait_ref {
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for impl_item_ref in refs {
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let impl_item = cx.tcx.hir().impl_item(impl_item_ref.id);
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if let ImplItemKind::Method(MethodSig{ decl: impl_decl, .. }, impl_body_id)
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= &impl_item.node {
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let item_type = cx.tcx.type_of(impl_def_id);
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check_trait_method_impl_decl(cx, item_type, impl_item, impl_decl, &impl_trait_ref);
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let body = cx.tcx.hir().body(*impl_body_id);
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visitor.visit_body(body);
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} else {
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visitor.visit_impl_item(impl_item);
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}
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}
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} else {
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for impl_item_ref in refs {
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let impl_item = cx.tcx.hir().impl_item(impl_item_ref.id);
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visitor.visit_impl_item(impl_item);
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}
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}
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}
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}
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}
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}
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}
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struct UseSelfVisitor<'a, 'tcx: 'a> {
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item_path: &'a Path,
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cx: &'a LateContext<'a, 'tcx>,
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}
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impl<'a, 'tcx> Visitor<'tcx> for UseSelfVisitor<'a, 'tcx> {
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fn visit_path(&mut self, path: &'tcx Path, _id: HirId) {
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if path.segments.last().expect(SEGMENTS_MSG).ident.name != SelfUpper.name() {
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if self.item_path.def == path.def {
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span_use_self_lint(self.cx, path);
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} else if let Def::StructCtor(ctor_did, CtorKind::Fn) = path.def {
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if self.item_path.def.opt_def_id() == self.cx.tcx.parent_def_id(ctor_did) {
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span_use_self_lint(self.cx, path);
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}
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}
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}
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walk_path(self, path);
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}
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fn visit_use(&mut self, _path: &'tcx Path, _id: NodeId, _hir_id: HirId) {
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// Don't check use statements
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}
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fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
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NestedVisitorMap::All(&self.cx.tcx.hir())
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}
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}
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