clang-tools-extra/clang-tidy/misc/UnusedUsingDeclsCheck.h

   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;
  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 {
  37     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