1 //===--- UsingNamespaceDirectiveCheck.cpp - 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 #include "UsingNamespaceDirectiveCheck.h" 10 #include "clang/AST/ASTContext.h" 11 #include "clang/ASTMatchers/ASTMatchFinder.h" 12 #include "clang/ASTMatchers/ASTMatchers.h" 13 14 using namespace clang::ast_matchers; 15 16 namespace clang { 17 namespace tidy { 18 namespace google { 19 namespace build { 20 registerMatchers(ast_matchers::MatchFinder * Finder)21void UsingNamespaceDirectiveCheck::registerMatchers( 22 ast_matchers::MatchFinder *Finder) { 23 // Only register the matchers for C++; the functionality currently does not 24 // provide any benefit to other languages, despite being benign. 25 if (getLangOpts().CPlusPlus) 26 Finder->addMatcher(usingDirectiveDecl().bind("usingNamespace"), this); 27 } 28 check(const MatchFinder::MatchResult & Result)29void UsingNamespaceDirectiveCheck::check( 30 const MatchFinder::MatchResult &Result) { 31 const auto *U = Result.Nodes.getNodeAs<UsingDirectiveDecl>("usingNamespace"); 32 SourceLocation Loc = U->getBeginLoc(); 33 if (U->isImplicit() || !Loc.isValid()) 34 return; 35 36 // Do not warn if namespace is a std namespace with user-defined literals. The 37 // user-defined literals can only be used with a using directive. 38 if (isStdLiteralsNamespace(U->getNominatedNamespace())) 39 return; 40 41 diag(Loc, "do not use namespace using-directives; " 42 "use using-declarations instead"); 43 // TODO: We could suggest a list of using directives replacing the using 44 // namespace directive. 45 } 46 isStdLiteralsNamespace(const NamespaceDecl * NS)47bool UsingNamespaceDirectiveCheck::isStdLiteralsNamespace( 48 const NamespaceDecl *NS) { 49 if (!NS->getName().endswith("literals")) 50 return false; 51 52 const auto *Parent = dyn_cast_or_null<NamespaceDecl>(NS->getParent()); 53 if (!Parent) 54 return false; 55 56 if (Parent->isStdNamespace()) 57 return true; 58 59 return Parent->getName() == "literals" && Parent->getParent() && 60 Parent->getParent()->isStdNamespace(); 61 } 62 } // namespace build 63 } // namespace google 64 } // namespace tidy 65 } // namespace clang 66