1 //===--- UnusedUsingDeclsCheck.h - clang-tidy--------------------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MISC_UNUSED_USING_DECLS_H
10 #define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MISC_UNUSED_USING_DECLS_H
11 
12 #include "../ClangTidyCheck.h"
13 #include "../utils/FileExtensionsUtils.h"
14 #include "llvm/ADT/SmallPtrSet.h"
15 #include <vector>
16 
17 namespace clang::tidy::misc {
18 
19 /// Finds unused using declarations.
20 ///
21 /// For the user-facing documentation see:
22 /// http://clang.llvm.org/extra/clang-tidy/checks/misc/unused-using-decls.html
23 class UnusedUsingDeclsCheck : public ClangTidyCheck {
24 public:
25   UnusedUsingDeclsCheck(StringRef Name, ClangTidyContext *Context);
26   void registerMatchers(ast_matchers::MatchFinder *Finder) override;
27   void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
28   void onEndOfTranslationUnit() override;
isLanguageVersionSupported(const LangOptions & LangOpts)29   bool isLanguageVersionSupported(const LangOptions &LangOpts) const override {
30     return LangOpts.CPlusPlus;
31   }
32 
33 private:
34   void removeFromFoundDecls(const Decl *D);
35 
36   struct UsingDeclContext {
UsingDeclContextUsingDeclContext37     explicit UsingDeclContext(const UsingDecl *FoundUsingDecl)
38         : FoundUsingDecl(FoundUsingDecl) {}
39     // A set saves all UsingShadowDecls introduced by a UsingDecl. A UsingDecl
40     // can introduce multiple UsingShadowDecls in some cases (such as
41     // overloaded functions).
42     llvm::SmallPtrSet<const Decl *, 4> UsingTargetDecls;
43     // The original UsingDecl.
44     const UsingDecl *FoundUsingDecl;
45     // The source range of the UsingDecl.
46     CharSourceRange UsingDeclRange;
47     // Whether the UsingDecl is used.
48     bool IsUsed = false;
49   };
50 
51   std::vector<UsingDeclContext> Contexts;
52   llvm::SmallPtrSet<const Decl *, 32> UsingTargetDeclsCache;
53 
54   StringRef RawStringHeaderFileExtensions;
55   FileExtensionsSet HeaderFileExtensions;
56 };
57 
58 } // namespace clang::tidy::misc
59 
60 #endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MISC_UNUSED_USING_DECLS_H
61