--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/clang/lib/Frontend/InitHeaderSearch.cpp	Thu Feb 13 15:10:13 2020 +0900
@@ -0,0 +1,649 @@
+//===--- InitHeaderSearch.cpp - Initialize header search paths ------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the InitHeaderSearch class.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/Basic/FileManager.h"
+#include "clang/Basic/LangOptions.h"
+#include "clang/Config/config.h" // C_INCLUDE_DIRS
+#include "clang/Frontend/FrontendDiagnostic.h"
+#include "clang/Frontend/Utils.h"
+#include "clang/Lex/HeaderMap.h"
+#include "clang/Lex/HeaderSearch.h"
+#include "clang/Lex/HeaderSearchOptions.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/SmallString.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/StringExtras.h"
+#include "llvm/ADT/Triple.h"
+#include "llvm/ADT/Twine.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/Path.h"
+#include "llvm/Support/raw_ostream.h"
+
+using namespace clang;
+using namespace clang::frontend;
+
+namespace {
+
+/// InitHeaderSearch - This class makes it easier to set the search paths of
+///  a HeaderSearch object. InitHeaderSearch stores several search path lists
+///  internally, which can be sent to a HeaderSearch object in one swoop.
+class InitHeaderSearch {
+  std::vector<std::pair<IncludeDirGroup, DirectoryLookup> > IncludePath;
+  typedef std::vector<std::pair<IncludeDirGroup,
+                      DirectoryLookup> >::const_iterator path_iterator;
+  std::vector<std::pair<std::string, bool> > SystemHeaderPrefixes;
+  HeaderSearch &Headers;
+  bool Verbose;
+  std::string IncludeSysroot;
+  bool HasSysroot;
+
+public:
+  InitHeaderSearch(HeaderSearch &HS, bool verbose, StringRef sysroot)
+      : Headers(HS), Verbose(verbose), IncludeSysroot(std::string(sysroot)),
+        HasSysroot(!(sysroot.empty() || sysroot == "/")) {}
+
+  /// AddPath - Add the specified path to the specified group list, prefixing
+  /// the sysroot if used.
+  /// Returns true if the path exists, false if it was ignored.
+  bool AddPath(const Twine &Path, IncludeDirGroup Group, bool isFramework);
+
+  /// AddUnmappedPath - Add the specified path to the specified group list,
+  /// without performing any sysroot remapping.
+  /// Returns true if the path exists, false if it was ignored.
+  bool AddUnmappedPath(const Twine &Path, IncludeDirGroup Group,
+                       bool isFramework);
+
+  /// AddSystemHeaderPrefix - Add the specified prefix to the system header
+  /// prefix list.
+  void AddSystemHeaderPrefix(StringRef Prefix, bool IsSystemHeader) {
+    SystemHeaderPrefixes.emplace_back(std::string(Prefix), IsSystemHeader);
+  }
+
+  /// AddGnuCPlusPlusIncludePaths - Add the necessary paths to support a gnu
+  ///  libstdc++.
+  /// Returns true if the \p Base path was found, false if it does not exist.
+  bool AddGnuCPlusPlusIncludePaths(StringRef Base, StringRef ArchDir,
+                                   StringRef Dir32, StringRef Dir64,
+                                   const llvm::Triple &triple);
+
+  /// AddMinGWCPlusPlusIncludePaths - Add the necessary paths to support a MinGW
+  ///  libstdc++.
+  void AddMinGWCPlusPlusIncludePaths(StringRef Base,
+                                     StringRef Arch,
+                                     StringRef Version);
+
+  // AddDefaultCIncludePaths - Add paths that should always be searched.
+  void AddDefaultCIncludePaths(const llvm::Triple &triple,
+                               const HeaderSearchOptions &HSOpts);
+
+  // AddDefaultCPlusPlusIncludePaths -  Add paths that should be searched when
+  //  compiling c++.
+  void AddDefaultCPlusPlusIncludePaths(const LangOptions &LangOpts,
+                                       const llvm::Triple &triple,
+                                       const HeaderSearchOptions &HSOpts);
+
+  /// AddDefaultSystemIncludePaths - Adds the default system include paths so
+  ///  that e.g. stdio.h is found.
+  void AddDefaultIncludePaths(const LangOptions &Lang,
+                              const llvm::Triple &triple,
+                              const HeaderSearchOptions &HSOpts);
+
+  /// Realize - Merges all search path lists into one list and send it to
+  /// HeaderSearch.
+  void Realize(const LangOptions &Lang);
+};
+
+}  // end anonymous namespace.
+
+static bool CanPrefixSysroot(StringRef Path) {
+#if defined(_WIN32)
+  return !Path.empty() && llvm::sys::path::is_separator(Path[0]);
+#else
+  return llvm::sys::path::is_absolute(Path);
+#endif
+}
+
+bool InitHeaderSearch::AddPath(const Twine &Path, IncludeDirGroup Group,
+                               bool isFramework) {
+  // Add the path with sysroot prepended, if desired and this is a system header
+  // group.
+  if (HasSysroot) {
+    SmallString<256> MappedPathStorage;
+    StringRef MappedPathStr = Path.toStringRef(MappedPathStorage);
+    if (CanPrefixSysroot(MappedPathStr)) {
+      return AddUnmappedPath(IncludeSysroot + Path, Group, isFramework);
+    }
+  }
+
+  return AddUnmappedPath(Path, Group, isFramework);
+}
+
+bool InitHeaderSearch::AddUnmappedPath(const Twine &Path, IncludeDirGroup Group,
+                                       bool isFramework) {
+  assert(!Path.isTriviallyEmpty() && "can't handle empty path here");
+
+  FileManager &FM = Headers.getFileMgr();
+  SmallString<256> MappedPathStorage;
+  StringRef MappedPathStr = Path.toStringRef(MappedPathStorage);
+
+  // If use system headers while cross-compiling, emit the warning.
+  if (HasSysroot && (MappedPathStr.startswith("/usr/include") ||
+                     MappedPathStr.startswith("/usr/local/include"))) {
+    Headers.getDiags().Report(diag::warn_poison_system_directories)
+        << MappedPathStr;
+  }
+
+  // Compute the DirectoryLookup type.
+  SrcMgr::CharacteristicKind Type;
+  if (Group == Quoted || Group == Angled || Group == IndexHeaderMap) {
+    Type = SrcMgr::C_User;
+  } else if (Group == ExternCSystem) {
+    Type = SrcMgr::C_ExternCSystem;
+  } else {
+    Type = SrcMgr::C_System;
+  }
+
+  // If the directory exists, add it.
+  if (auto DE = FM.getOptionalDirectoryRef(MappedPathStr)) {
+    IncludePath.push_back(
+      std::make_pair(Group, DirectoryLookup(*DE, Type, isFramework)));
+    return true;
+  }
+
+  // Check to see if this is an apple-style headermap (which are not allowed to
+  // be frameworks).
+  if (!isFramework) {
+    if (auto FE = FM.getFile(MappedPathStr)) {
+      if (const HeaderMap *HM = Headers.CreateHeaderMap(*FE)) {
+        // It is a headermap, add it to the search path.
+        IncludePath.push_back(
+          std::make_pair(Group,
+                         DirectoryLookup(HM, Type, Group == IndexHeaderMap)));
+        return true;
+      }
+    }
+  }
+
+  if (Verbose)
+    llvm::errs() << "ignoring nonexistent directory \""
+                 << MappedPathStr << "\"\n";
+  return false;
+}
+
+bool InitHeaderSearch::AddGnuCPlusPlusIncludePaths(StringRef Base,
+                                                   StringRef ArchDir,
+                                                   StringRef Dir32,
+                                                   StringRef Dir64,
+                                                   const llvm::Triple &triple) {
+  // Add the base dir
+  bool IsBaseFound = AddPath(Base, CXXSystem, false);
+
+  // Add the multilib dirs
+  llvm::Triple::ArchType arch = triple.getArch();
+  bool is64bit = arch == llvm::Triple::ppc64 || arch == llvm::Triple::x86_64;
+  if (is64bit)
+    AddPath(Base + "/" + ArchDir + "/" + Dir64, CXXSystem, false);
+  else
+    AddPath(Base + "/" + ArchDir + "/" + Dir32, CXXSystem, false);
+
+  // Add the backward dir
+  AddPath(Base + "/backward", CXXSystem, false);
+  return IsBaseFound;
+}
+
+void InitHeaderSearch::AddMinGWCPlusPlusIncludePaths(StringRef Base,
+                                                     StringRef Arch,
+                                                     StringRef Version) {
+  AddPath(Base + "/" + Arch + "/" + Version + "/include/c++",
+          CXXSystem, false);
+  AddPath(Base + "/" + Arch + "/" + Version + "/include/c++/" + Arch,
+          CXXSystem, false);
+  AddPath(Base + "/" + Arch + "/" + Version + "/include/c++/backward",
+          CXXSystem, false);
+}
+
+void InitHeaderSearch::AddDefaultCIncludePaths(const llvm::Triple &triple,
+                                            const HeaderSearchOptions &HSOpts) {
+  llvm::Triple::OSType os = triple.getOS();
+
+  if (triple.isOSDarwin()) {
+    llvm_unreachable("Include management is handled in the driver.");
+  }
+
+  if (HSOpts.UseStandardSystemIncludes) {
+    switch (os) {
+    case llvm::Triple::CloudABI:
+    case llvm::Triple::FreeBSD:
+    case llvm::Triple::NetBSD:
+    case llvm::Triple::OpenBSD:
+    case llvm::Triple::NaCl:
+    case llvm::Triple::PS4:
+    case llvm::Triple::ELFIAMCU:
+    case llvm::Triple::Fuchsia:
+      break;
+    case llvm::Triple::Win32:
+      if (triple.getEnvironment() != llvm::Triple::Cygnus)
+        break;
+      LLVM_FALLTHROUGH;
+    default:
+      // FIXME: temporary hack: hard-coded paths.
+      AddPath("/usr/local/include", System, false);
+      break;
+    }
+  }
+
+  // Builtin includes use #include_next directives and should be positioned
+  // just prior C include dirs.
+  if (HSOpts.UseBuiltinIncludes) {
+    // Ignore the sys root, we *always* look for clang headers relative to
+    // supplied path.
+    SmallString<128> P = StringRef(HSOpts.ResourceDir);
+    llvm::sys::path::append(P, "include");
+    AddUnmappedPath(P, ExternCSystem, false);
+  }
+
+  // All remaining additions are for system include directories, early exit if
+  // we aren't using them.
+  if (!HSOpts.UseStandardSystemIncludes)
+    return;
+
+  // Add dirs specified via 'configure --with-c-include-dirs'.
+  StringRef CIncludeDirs(C_INCLUDE_DIRS);
+  if (CIncludeDirs != "") {
+    SmallVector<StringRef, 5> dirs;
+    CIncludeDirs.split(dirs, ":");
+    for (StringRef dir : dirs)
+      AddPath(dir, ExternCSystem, false);
+    return;
+  }
+
+  switch (os) {
+  case llvm::Triple::Linux:
+  case llvm::Triple::Hurd:
+  case llvm::Triple::Solaris:
+    llvm_unreachable("Include management is handled in the driver.");
+
+  case llvm::Triple::CloudABI: {
+    // <sysroot>/<triple>/include
+    SmallString<128> P = StringRef(HSOpts.ResourceDir);
+    llvm::sys::path::append(P, "../../..", triple.str(), "include");
+    AddPath(P, System, false);
+    break;
+  }
+
+  case llvm::Triple::Haiku:
+    AddPath("/boot/system/non-packaged/develop/headers", System, false);
+    AddPath("/boot/system/develop/headers/os", System, false);
+    AddPath("/boot/system/develop/headers/os/app", System, false);
+    AddPath("/boot/system/develop/headers/os/arch", System, false);
+    AddPath("/boot/system/develop/headers/os/device", System, false);
+    AddPath("/boot/system/develop/headers/os/drivers", System, false);
+    AddPath("/boot/system/develop/headers/os/game", System, false);
+    AddPath("/boot/system/develop/headers/os/interface", System, false);
+    AddPath("/boot/system/develop/headers/os/kernel", System, false);
+    AddPath("/boot/system/develop/headers/os/locale", System, false);
+    AddPath("/boot/system/develop/headers/os/mail", System, false);
+    AddPath("/boot/system/develop/headers/os/media", System, false);
+    AddPath("/boot/system/develop/headers/os/midi", System, false);
+    AddPath("/boot/system/develop/headers/os/midi2", System, false);
+    AddPath("/boot/system/develop/headers/os/net", System, false);
+    AddPath("/boot/system/develop/headers/os/opengl", System, false);
+    AddPath("/boot/system/develop/headers/os/storage", System, false);
+    AddPath("/boot/system/develop/headers/os/support", System, false);
+    AddPath("/boot/system/develop/headers/os/translation", System, false);
+    AddPath("/boot/system/develop/headers/os/add-ons/graphics", System, false);
+    AddPath("/boot/system/develop/headers/os/add-ons/input_server", System, false);
+    AddPath("/boot/system/develop/headers/os/add-ons/mail_daemon", System, false);
+    AddPath("/boot/system/develop/headers/os/add-ons/registrar", System, false);
+    AddPath("/boot/system/develop/headers/os/add-ons/screen_saver", System, false);
+    AddPath("/boot/system/develop/headers/os/add-ons/tracker", System, false);
+    AddPath("/boot/system/develop/headers/os/be_apps/Deskbar", System, false);
+    AddPath("/boot/system/develop/headers/os/be_apps/NetPositive", System, false);
+    AddPath("/boot/system/develop/headers/os/be_apps/Tracker", System, false);
+    AddPath("/boot/system/develop/headers/3rdparty", System, false);
+    AddPath("/boot/system/develop/headers/bsd", System, false);
+    AddPath("/boot/system/develop/headers/glibc", System, false);
+    AddPath("/boot/system/develop/headers/posix", System, false);
+    AddPath("/boot/system/develop/headers",  System, false);
+    break;
+  case llvm::Triple::RTEMS:
+    break;
+  case llvm::Triple::Win32:
+    switch (triple.getEnvironment()) {
+    default: llvm_unreachable("Include management is handled in the driver.");
+    case llvm::Triple::Cygnus:
+      AddPath("/usr/include/w32api", System, false);
+      break;
+    case llvm::Triple::GNU:
+      break;
+    }
+    break;
+  default:
+    break;
+  }
+
+  switch (os) {
+  case llvm::Triple::CloudABI:
+  case llvm::Triple::RTEMS:
+  case llvm::Triple::NaCl:
+  case llvm::Triple::ELFIAMCU:
+  case llvm::Triple::Fuchsia:
+    break;
+  case llvm::Triple::PS4: {
+    // <isysroot> gets prepended later in AddPath().
+    std::string BaseSDKPath = "";
+    if (!HasSysroot) {
+      const char *envValue = getenv("SCE_ORBIS_SDK_DIR");
+      if (envValue)
+        BaseSDKPath = envValue;
+      else {
+        // HSOpts.ResourceDir variable contains the location of Clang's
+        // resource files.
+        // Assuming that Clang is configured for PS4 without
+        // --with-clang-resource-dir option, the location of Clang's resource
+        // files is <SDK_DIR>/host_tools/lib/clang
+        SmallString<128> P = StringRef(HSOpts.ResourceDir);
+        llvm::sys::path::append(P, "../../..");
+        BaseSDKPath = std::string(P.str());
+      }
+    }
+    AddPath(BaseSDKPath + "/target/include", System, false);
+    if (triple.isPS4CPU())
+      AddPath(BaseSDKPath + "/target/include_common", System, false);
+    LLVM_FALLTHROUGH;
+  }
+  default:
+    AddPath("/usr/include", ExternCSystem, false);
+    break;
+  }
+}
+
+void InitHeaderSearch::AddDefaultCPlusPlusIncludePaths(
+    const LangOptions &LangOpts, const llvm::Triple &triple,
+    const HeaderSearchOptions &HSOpts) {
+  llvm::Triple::OSType os = triple.getOS();
+  // FIXME: temporary hack: hard-coded paths.
+
+  if (triple.isOSDarwin()) {
+    llvm_unreachable("Include management is handled in the driver.");
+  }
+
+  switch (os) {
+  case llvm::Triple::Linux:
+  case llvm::Triple::Hurd:
+  case llvm::Triple::Solaris:
+    llvm_unreachable("Include management is handled in the driver.");
+    break;
+  case llvm::Triple::Win32:
+    switch (triple.getEnvironment()) {
+    default: llvm_unreachable("Include management is handled in the driver.");
+    case llvm::Triple::Cygnus:
+      // Cygwin-1.7
+      AddMinGWCPlusPlusIncludePaths("/usr/lib/gcc", "i686-pc-cygwin", "4.7.3");
+      AddMinGWCPlusPlusIncludePaths("/usr/lib/gcc", "i686-pc-cygwin", "4.5.3");
+      AddMinGWCPlusPlusIncludePaths("/usr/lib/gcc", "i686-pc-cygwin", "4.3.4");
+      // g++-4 / Cygwin-1.5
+      AddMinGWCPlusPlusIncludePaths("/usr/lib/gcc", "i686-pc-cygwin", "4.3.2");
+      break;
+    }
+    break;
+  case llvm::Triple::DragonFly:
+    AddPath("/usr/include/c++/5.0", CXXSystem, false);
+    break;
+  case llvm::Triple::Minix:
+    AddGnuCPlusPlusIncludePaths("/usr/gnu/include/c++/4.4.3",
+                                "", "", "", triple);
+    break;
+  default:
+    break;
+  }
+}
+
+void InitHeaderSearch::AddDefaultIncludePaths(const LangOptions &Lang,
+                                              const llvm::Triple &triple,
+                                            const HeaderSearchOptions &HSOpts) {
+  // NB: This code path is going away. All of the logic is moving into the
+  // driver which has the information necessary to do target-specific
+  // selections of default include paths. Each target which moves there will be
+  // exempted from this logic here until we can delete the entire pile of code.
+  switch (triple.getOS()) {
+  default:
+    break; // Everything else continues to use this routine's logic.
+
+  case llvm::Triple::Emscripten:
+  case llvm::Triple::Linux:
+  case llvm::Triple::Hurd:
+  case llvm::Triple::Solaris:
+  case llvm::Triple::WASI:
+    return;
+
+  case llvm::Triple::Win32:
+    if (triple.getEnvironment() != llvm::Triple::Cygnus ||
+        triple.isOSBinFormatMachO())
+      return;
+    break;
+
+  case llvm::Triple::UnknownOS:
+    if (triple.getArch() == llvm::Triple::wasm32 ||
+        triple.getArch() == llvm::Triple::wasm64)
+      return;
+    break;
+  }
+
+  // All header search logic is handled in the Driver for Darwin.
+  if (triple.isOSDarwin()) {
+    if (HSOpts.UseStandardSystemIncludes) {
+      // Add the default framework include paths on Darwin.
+      AddPath("/System/Library/Frameworks", System, true);
+      AddPath("/Library/Frameworks", System, true);
+    }
+    return;
+  }
+
+  if (Lang.CPlusPlus && !Lang.AsmPreprocessor &&
+      HSOpts.UseStandardCXXIncludes && HSOpts.UseStandardSystemIncludes) {
+    if (HSOpts.UseLibcxx) {
+      AddPath("/usr/include/c++/v1", CXXSystem, false);
+    } else {
+      AddDefaultCPlusPlusIncludePaths(Lang, triple, HSOpts);
+    }
+  }
+
+  AddDefaultCIncludePaths(triple, HSOpts);
+}
+
+/// RemoveDuplicates - If there are duplicate directory entries in the specified
+/// search list, remove the later (dead) ones.  Returns the number of non-system
+/// headers removed, which is used to update NumAngled.
+static unsigned RemoveDuplicates(std::vector<DirectoryLookup> &SearchList,
+                                 unsigned First, bool Verbose) {
+  llvm::SmallPtrSet<const DirectoryEntry *, 8> SeenDirs;
+  llvm::SmallPtrSet<const DirectoryEntry *, 8> SeenFrameworkDirs;
+  llvm::SmallPtrSet<const HeaderMap *, 8> SeenHeaderMaps;
+  unsigned NonSystemRemoved = 0;
+  for (unsigned i = First; i != SearchList.size(); ++i) {
+    unsigned DirToRemove = i;
+
+    const DirectoryLookup &CurEntry = SearchList[i];
+
+    if (CurEntry.isNormalDir()) {
+      // If this isn't the first time we've seen this dir, remove it.
+      if (SeenDirs.insert(CurEntry.getDir()).second)
+        continue;
+    } else if (CurEntry.isFramework()) {
+      // If this isn't the first time we've seen this framework dir, remove it.
+      if (SeenFrameworkDirs.insert(CurEntry.getFrameworkDir()).second)
+        continue;
+    } else {
+      assert(CurEntry.isHeaderMap() && "Not a headermap or normal dir?");
+      // If this isn't the first time we've seen this headermap, remove it.
+      if (SeenHeaderMaps.insert(CurEntry.getHeaderMap()).second)
+        continue;
+    }
+
+    // If we have a normal #include dir/framework/headermap that is shadowed
+    // later in the chain by a system include location, we actually want to
+    // ignore the user's request and drop the user dir... keeping the system
+    // dir.  This is weird, but required to emulate GCC's search path correctly.
+    //
+    // Since dupes of system dirs are rare, just rescan to find the original
+    // that we're nuking instead of using a DenseMap.
+    if (CurEntry.getDirCharacteristic() != SrcMgr::C_User) {
+      // Find the dir that this is the same of.
+      unsigned FirstDir;
+      for (FirstDir = First;; ++FirstDir) {
+        assert(FirstDir != i && "Didn't find dupe?");
+
+        const DirectoryLookup &SearchEntry = SearchList[FirstDir];
+
+        // If these are different lookup types, then they can't be the dupe.
+        if (SearchEntry.getLookupType() != CurEntry.getLookupType())
+          continue;
+
+        bool isSame;
+        if (CurEntry.isNormalDir())
+          isSame = SearchEntry.getDir() == CurEntry.getDir();
+        else if (CurEntry.isFramework())
+          isSame = SearchEntry.getFrameworkDir() == CurEntry.getFrameworkDir();
+        else {
+          assert(CurEntry.isHeaderMap() && "Not a headermap or normal dir?");
+          isSame = SearchEntry.getHeaderMap() == CurEntry.getHeaderMap();
+        }
+
+        if (isSame)
+          break;
+      }
+
+      // If the first dir in the search path is a non-system dir, zap it
+      // instead of the system one.
+      if (SearchList[FirstDir].getDirCharacteristic() == SrcMgr::C_User)
+        DirToRemove = FirstDir;
+    }
+
+    if (Verbose) {
+      llvm::errs() << "ignoring duplicate directory \""
+                   << CurEntry.getName() << "\"\n";
+      if (DirToRemove != i)
+        llvm::errs() << "  as it is a non-system directory that duplicates "
+                     << "a system directory\n";
+    }
+    if (DirToRemove != i)
+      ++NonSystemRemoved;
+
+    // This is reached if the current entry is a duplicate.  Remove the
+    // DirToRemove (usually the current dir).
+    SearchList.erase(SearchList.begin()+DirToRemove);
+    --i;
+  }
+  return NonSystemRemoved;
+}
+
+
+void InitHeaderSearch::Realize(const LangOptions &Lang) {
+  // Concatenate ANGLE+SYSTEM+AFTER chains together into SearchList.
+  std::vector<DirectoryLookup> SearchList;
+  SearchList.reserve(IncludePath.size());
+
+  // Quoted arguments go first.
+  for (auto &Include : IncludePath)
+    if (Include.first == Quoted)
+      SearchList.push_back(Include.second);
+
+  // Deduplicate and remember index.
+  RemoveDuplicates(SearchList, 0, Verbose);
+  unsigned NumQuoted = SearchList.size();
+
+  for (auto &Include : IncludePath)
+    if (Include.first == Angled || Include.first == IndexHeaderMap)
+      SearchList.push_back(Include.second);
+
+  RemoveDuplicates(SearchList, NumQuoted, Verbose);
+  unsigned NumAngled = SearchList.size();
+
+  for (auto &Include : IncludePath)
+    if (Include.first == System || Include.first == ExternCSystem ||
+        (!Lang.ObjC && !Lang.CPlusPlus && Include.first == CSystem) ||
+        (/*FIXME !Lang.ObjC && */ Lang.CPlusPlus &&
+         Include.first == CXXSystem) ||
+        (Lang.ObjC && !Lang.CPlusPlus && Include.first == ObjCSystem) ||
+        (Lang.ObjC && Lang.CPlusPlus && Include.first == ObjCXXSystem))
+      SearchList.push_back(Include.second);
+
+  for (auto &Include : IncludePath)
+    if (Include.first == After)
+      SearchList.push_back(Include.second);
+
+  // Remove duplicates across both the Angled and System directories.  GCC does
+  // this and failing to remove duplicates across these two groups breaks
+  // #include_next.
+  unsigned NonSystemRemoved = RemoveDuplicates(SearchList, NumQuoted, Verbose);
+  NumAngled -= NonSystemRemoved;
+
+  bool DontSearchCurDir = false;  // TODO: set to true if -I- is set?
+  Headers.SetSearchPaths(SearchList, NumQuoted, NumAngled, DontSearchCurDir);
+
+  Headers.SetSystemHeaderPrefixes(SystemHeaderPrefixes);
+
+  // If verbose, print the list of directories that will be searched.
+  if (Verbose) {
+    llvm::errs() << "#include \"...\" search starts here:\n";
+    for (unsigned i = 0, e = SearchList.size(); i != e; ++i) {
+      if (i == NumQuoted)
+        llvm::errs() << "#include <...> search starts here:\n";
+      StringRef Name = SearchList[i].getName();
+      const char *Suffix;
+      if (SearchList[i].isNormalDir())
+        Suffix = "";
+      else if (SearchList[i].isFramework())
+        Suffix = " (framework directory)";
+      else {
+        assert(SearchList[i].isHeaderMap() && "Unknown DirectoryLookup");
+        Suffix = " (headermap)";
+      }
+      llvm::errs() << " " << Name << Suffix << "\n";
+    }
+    llvm::errs() << "End of search list.\n";
+  }
+}
+
+void clang::ApplyHeaderSearchOptions(HeaderSearch &HS,
+                                     const HeaderSearchOptions &HSOpts,
+                                     const LangOptions &Lang,
+                                     const llvm::Triple &Triple) {
+  InitHeaderSearch Init(HS, HSOpts.Verbose, HSOpts.Sysroot);
+
+  // Add the user defined entries.
+  for (unsigned i = 0, e = HSOpts.UserEntries.size(); i != e; ++i) {
+    const HeaderSearchOptions::Entry &E = HSOpts.UserEntries[i];
+    if (E.IgnoreSysRoot) {
+      Init.AddUnmappedPath(E.Path, E.Group, E.IsFramework);
+    } else {
+      Init.AddPath(E.Path, E.Group, E.IsFramework);
+    }
+  }
+
+  Init.AddDefaultIncludePaths(Lang, Triple, HSOpts);
+
+  for (unsigned i = 0, e = HSOpts.SystemHeaderPrefixes.size(); i != e; ++i)
+    Init.AddSystemHeaderPrefix(HSOpts.SystemHeaderPrefixes[i].Prefix,
+                               HSOpts.SystemHeaderPrefixes[i].IsSystemHeader);
+
+  if (HSOpts.UseBuiltinIncludes) {
+    // Set up the builtin include directory in the module map.
+    SmallString<128> P = StringRef(HSOpts.ResourceDir);
+    llvm::sys::path::append(P, "include");
+    if (auto Dir = HS.getFileMgr().getDirectory(P))
+      HS.getModuleMap().setBuiltinIncludeDir(*Dir);
+  }
+
+  Init.Realize(Lang);
+}