clang-tools-extra/clang-tidy/google/UsingNamespaceDirectiveCheck.cpp

   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::tidy::google::build {
  17
  18 void UsingNamespaceDirectiveCheck::registerMatchers(
  19     ast_matchers::MatchFinder *Finder) {
  20     Finder->addMatcher(usingDirectiveDecl().bind("usingNamespace"), this);
  21 }
  22
  23 void UsingNamespaceDirectiveCheck::check(
  24     const MatchFinder::MatchResult &Result) {
  25   const auto *U = Result.Nodes.getNodeAs<UsingDirectiveDecl>("usingNamespace");
  26   SourceLocation Loc = U->getBeginLoc();
  27   if (U->isImplicit() || !Loc.isValid())
  28     return;
  29
  30   // Do not warn if namespace is a std namespace with user-defined literals. The
  31   // user-defined literals can only be used with a using directive.
  32   if (isStdLiteralsNamespace(U->getNominatedNamespace()))
  33     return;
  34
  35   diag(Loc, "do not use namespace using-directives; "
  36             "use using-declarations instead");
  37   // TODO: We could suggest a list of using directives replacing the using
  38   //       namespace directive.
  39 }
  40
  41 bool UsingNamespaceDirectiveCheck::isStdLiteralsNamespace(
  42     const NamespaceDecl *NS) {
  43   if (!NS->getName().ends_with("literals"))
  44     return false;
  45
  46   const auto *Parent = dyn_cast_or_null<NamespaceDecl>(NS->getParent());
  47   if (!Parent)
  48     return false;
  49
  50   if (Parent->isStdNamespace())
  51     return true;
  52
  53   return Parent->getName() == "literals" && Parent->getParent() &&
  54          Parent->getParent()->isStdNamespace();
  55 }
  56 } // namespace clang::tidy::google::build