UsingNamespaceDirectiveCheck.cpp

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//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
 
#include "UsingNamespaceDirectiveCheck.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
#include "clang/ASTMatchers/ASTMatchers.h"
 
using namespace clang::ast_matchers;
 
namespace clang::tidy::google::build {
 
void UsingNamespaceDirectiveCheck::registerMatchers(
    ast_matchers::MatchFinder *Finder) {
  Finder->addMatcher(usingDirectiveDecl().bind("usingNamespace"), this);
}
 
void UsingNamespaceDirectiveCheck::check(
    const MatchFinder::MatchResult &Result) {
  const auto *U = Result.Nodes.getNodeAs<UsingDirectiveDecl>("usingNamespace");
  SourceLocation Loc = U->getBeginLoc();
  if (U->isImplicit() || !Loc.isValid())
    return;
 
  // Do not warn if namespace is a std namespace with user-defined literals. The
  // user-defined literals can only be used with a using directive.
  if (isStdLiteralsNamespace(U->getNominatedNamespace()))
    return;
 
  diag(Loc, "do not use namespace using-directives; "
            "use using-declarations instead");
  // TODO: We could suggest a list of using directives replacing the using
  //       namespace directive.
}
 
bool UsingNamespaceDirectiveCheck::isStdLiteralsNamespace(
    const NamespaceDecl *NS) {
  if (!NS->getName().ends_with("literals"))
    return false;
 
  const auto *Parent = dyn_cast_or_null<NamespaceDecl>(NS->getParent());
  if (!Parent)
    return false;
 
  if (Parent->isStdNamespace())
    return true;
 
  return Parent->getName() == "literals" && Parent->getParent() &&
         Parent->getParent()->isStdNamespace();
}
} // namespace clang::tidy::google::build