--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/clang/unittests/Lex/PPDependencyDirectivesTest.cpp	Wed Nov 09 17:45:10 2022 +0900
@@ -0,0 +1,148 @@
+//===- unittests/Lex/PPDependencyDirectivesTest.cpp -------------------------=//
+//
+// 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 "clang/Basic/Diagnostic.h"
+#include "clang/Basic/DiagnosticOptions.h"
+#include "clang/Basic/FileManager.h"
+#include "clang/Basic/LangOptions.h"
+#include "clang/Basic/SourceManager.h"
+#include "clang/Basic/TargetInfo.h"
+#include "clang/Basic/TargetOptions.h"
+#include "clang/Lex/DependencyDirectivesScanner.h"
+#include "clang/Lex/HeaderSearch.h"
+#include "clang/Lex/HeaderSearchOptions.h"
+#include "clang/Lex/ModuleLoader.h"
+#include "clang/Lex/Preprocessor.h"
+#include "clang/Lex/PreprocessorOptions.h"
+#include "llvm/Testing/Support/Error.h"
+#include "gtest/gtest.h"
+
+using namespace clang;
+
+namespace {
+
+// The test fixture.
+class PPDependencyDirectivesTest : public ::testing::Test {
+protected:
+  PPDependencyDirectivesTest()
+      : FileMgr(FileMgrOpts), DiagID(new DiagnosticIDs()),
+        Diags(DiagID, new DiagnosticOptions, new IgnoringDiagConsumer()),
+        SourceMgr(Diags, FileMgr), TargetOpts(new TargetOptions) {
+    TargetOpts->Triple = "x86_64-apple-macos12";
+    Target = TargetInfo::CreateTargetInfo(Diags, TargetOpts);
+  }
+
+  FileSystemOptions FileMgrOpts;
+  FileManager FileMgr;
+  IntrusiveRefCntPtr<DiagnosticIDs> DiagID;
+  DiagnosticsEngine Diags;
+  SourceManager SourceMgr;
+  LangOptions LangOpts;
+  std::shared_ptr<TargetOptions> TargetOpts;
+  IntrusiveRefCntPtr<TargetInfo> Target;
+};
+
+class IncludeCollector : public PPCallbacks {
+public:
+  Preprocessor &PP;
+  SmallVectorImpl<StringRef> &IncludedFiles;
+
+  IncludeCollector(Preprocessor &PP, SmallVectorImpl<StringRef> &IncludedFiles)
+      : PP(PP), IncludedFiles(IncludedFiles) {}
+
+  void LexedFileChanged(FileID FID, LexedFileChangeReason Reason,
+                        SrcMgr::CharacteristicKind FileType, FileID PrevFID,
+                        SourceLocation Loc) override {
+    if (Reason != LexedFileChangeReason::EnterFile)
+      return;
+    if (FID == PP.getPredefinesFileID())
+      return;
+    StringRef Filename =
+        PP.getSourceManager().getSLocEntry(FID).getFile().getName();
+    IncludedFiles.push_back(Filename);
+  }
+};
+
+TEST_F(PPDependencyDirectivesTest, MacroGuard) {
+  // "head1.h" has a macro guard and should only be included once.
+  // "head2.h" and "head3.h" have tokens following the macro check, they should
+  // be included multiple times.
+
+  auto VFS = new llvm::vfs::InMemoryFileSystem();
+  VFS->addFile(
+      "head1.h", 0,
+      llvm::MemoryBuffer::getMemBuffer("#ifndef H1_H\n#define H1_H\n#endif\n"));
+  VFS->addFile(
+      "head2.h", 0,
+      llvm::MemoryBuffer::getMemBuffer("#ifndef H2_H\n#define H2_H\n#endif\n\n"
+                                       "extern int foo;\n"));
+  VFS->addFile("head3.h", 0,
+               llvm::MemoryBuffer::getMemBuffer(
+                   "#ifndef H3_H\n#define H3_H\n#endif\n\n"
+                   "#ifdef SOMEMAC\nextern int foo;\n#endif\n"));
+  VFS->addFile("main.c", 0,
+               llvm::MemoryBuffer::getMemBuffer(
+                   "#include \"head1.h\"\n#include \"head1.h\"\n"
+                   "#include \"head2.h\"\n#include \"head2.h\"\n"
+                   "#include \"head3.h\"\n#include \"head3.h\"\n"));
+  FileMgr.setVirtualFileSystem(VFS);
+
+  Optional<FileEntryRef> FE;
+  ASSERT_THAT_ERROR(FileMgr.getFileRef("main.c").moveInto(FE),
+                    llvm::Succeeded());
+  SourceMgr.setMainFileID(
+      SourceMgr.createFileID(*FE, SourceLocation(), SrcMgr::C_User));
+
+  struct DepDirectives {
+    SmallVector<dependency_directives_scan::Token> Tokens;
+    SmallVector<dependency_directives_scan::Directive> Directives;
+  };
+  SmallVector<std::unique_ptr<DepDirectives>> DepDirectivesObjects;
+
+  auto getDependencyDirectives = [&](FileEntryRef File)
+      -> Optional<ArrayRef<dependency_directives_scan::Directive>> {
+    DepDirectivesObjects.push_back(std::make_unique<DepDirectives>());
+    StringRef Input = (*FileMgr.getBufferForFile(File))->getBuffer();
+    bool Err = scanSourceForDependencyDirectives(
+        Input, DepDirectivesObjects.back()->Tokens,
+        DepDirectivesObjects.back()->Directives);
+    EXPECT_FALSE(Err);
+    return llvm::makeArrayRef(DepDirectivesObjects.back()->Directives);
+  };
+
+  auto PPOpts = std::make_shared<PreprocessorOptions>();
+  PPOpts->DependencyDirectivesForFile = [&](FileEntryRef File)
+      -> Optional<ArrayRef<dependency_directives_scan::Directive>> {
+    return getDependencyDirectives(File);
+  };
+
+  TrivialModuleLoader ModLoader;
+  HeaderSearch HeaderInfo(std::make_shared<HeaderSearchOptions>(), SourceMgr,
+                          Diags, LangOpts, Target.get());
+  Preprocessor PP(PPOpts, Diags, LangOpts, SourceMgr, HeaderInfo, ModLoader,
+                  /*IILookup =*/nullptr,
+                  /*OwnsHeaderSearch =*/false);
+  PP.Initialize(*Target);
+
+  SmallVector<StringRef> IncludedFiles;
+  PP.addPPCallbacks(std::make_unique<IncludeCollector>(PP, IncludedFiles));
+  PP.EnterMainSourceFile();
+  while (true) {
+    Token tok;
+    PP.Lex(tok);
+    if (tok.is(tok::eof))
+      break;
+  }
+
+  SmallVector<StringRef> ExpectedIncludes{
+      "main.c", "./head1.h", "./head2.h", "./head2.h", "./head3.h", "./head3.h",
+  };
+  EXPECT_EQ(IncludedFiles, ExpectedIncludes);
+}
+
+} // anonymous namespace