xref: /freebsd/contrib/llvm-project/clang/lib/Lex/InitHeaderSearch.cpp (revision 734e82fe33aa764367791a7d603b383996c6b40b)
1 //===--- InitHeaderSearch.cpp - Initialize header search paths ------------===//
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 // This file implements the InitHeaderSearch class.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "clang/Basic/DiagnosticFrontend.h"
14 #include "clang/Basic/FileManager.h"
15 #include "clang/Basic/LangOptions.h"
16 #include "clang/Config/config.h" // C_INCLUDE_DIRS
17 #include "clang/Lex/HeaderMap.h"
18 #include "clang/Lex/HeaderSearch.h"
19 #include "clang/Lex/HeaderSearchOptions.h"
20 #include "llvm/ADT/SmallPtrSet.h"
21 #include "llvm/ADT/SmallString.h"
22 #include "llvm/ADT/SmallVector.h"
23 #include "llvm/ADT/StringExtras.h"
24 #include "llvm/ADT/Triple.h"
25 #include "llvm/ADT/Twine.h"
26 #include "llvm/Support/ErrorHandling.h"
27 #include "llvm/Support/Path.h"
28 #include "llvm/Support/raw_ostream.h"
29 #include <optional>
30 
31 using namespace clang;
32 using namespace clang::frontend;
33 
34 namespace {
35 /// Holds information about a single DirectoryLookup object.
36 struct DirectoryLookupInfo {
37   IncludeDirGroup Group;
38   DirectoryLookup Lookup;
39   std::optional<unsigned> UserEntryIdx;
40 
41   DirectoryLookupInfo(IncludeDirGroup Group, DirectoryLookup Lookup,
42                       std::optional<unsigned> UserEntryIdx)
43       : Group(Group), Lookup(Lookup), UserEntryIdx(UserEntryIdx) {}
44 };
45 
46 /// This class makes it easier to set the search paths of a HeaderSearch object.
47 /// InitHeaderSearch stores several search path lists internally, which can be
48 /// sent to a HeaderSearch object in one swoop.
49 class InitHeaderSearch {
50   std::vector<DirectoryLookupInfo> IncludePath;
51   std::vector<std::pair<std::string, bool> > SystemHeaderPrefixes;
52   HeaderSearch &Headers;
53   bool Verbose;
54   std::string IncludeSysroot;
55   bool HasSysroot;
56 
57 public:
58   InitHeaderSearch(HeaderSearch &HS, bool verbose, StringRef sysroot)
59       : Headers(HS), Verbose(verbose), IncludeSysroot(std::string(sysroot)),
60         HasSysroot(!(sysroot.empty() || sysroot == "/")) {}
61 
62   /// Add the specified path to the specified group list, prefixing the sysroot
63   /// if used.
64   /// Returns true if the path exists, false if it was ignored.
65   bool AddPath(const Twine &Path, IncludeDirGroup Group, bool isFramework,
66                std::optional<unsigned> UserEntryIdx = std::nullopt);
67 
68   /// Add the specified path to the specified group list, without performing any
69   /// sysroot remapping.
70   /// Returns true if the path exists, false if it was ignored.
71   bool AddUnmappedPath(const Twine &Path, IncludeDirGroup Group,
72                        bool isFramework,
73                        std::optional<unsigned> UserEntryIdx = std::nullopt);
74 
75   /// Add the specified prefix to the system header prefix list.
76   void AddSystemHeaderPrefix(StringRef Prefix, bool IsSystemHeader) {
77     SystemHeaderPrefixes.emplace_back(std::string(Prefix), IsSystemHeader);
78   }
79 
80   /// Add the necessary paths to support a gnu libstdc++.
81   /// Returns true if the \p Base path was found, false if it does not exist.
82   bool AddGnuCPlusPlusIncludePaths(StringRef Base, StringRef ArchDir,
83                                    StringRef Dir32, StringRef Dir64,
84                                    const llvm::Triple &triple);
85 
86   /// Add the necessary paths to support a MinGW libstdc++.
87   void AddMinGWCPlusPlusIncludePaths(StringRef Base,
88                                      StringRef Arch,
89                                      StringRef Version);
90 
91   /// Add paths that should always be searched.
92   void AddDefaultCIncludePaths(const llvm::Triple &triple,
93                                const HeaderSearchOptions &HSOpts);
94 
95   /// Add paths that should be searched when compiling c++.
96   void AddDefaultCPlusPlusIncludePaths(const LangOptions &LangOpts,
97                                        const llvm::Triple &triple,
98                                        const HeaderSearchOptions &HSOpts);
99 
100   /// Returns true iff AddDefaultIncludePaths should do anything.  If this
101   /// returns false, include paths should instead be handled in the driver.
102   bool ShouldAddDefaultIncludePaths(const llvm::Triple &triple);
103 
104   /// Adds the default system include paths so that e.g. stdio.h is found.
105   void AddDefaultIncludePaths(const LangOptions &Lang,
106                               const llvm::Triple &triple,
107                               const HeaderSearchOptions &HSOpts);
108 
109   /// Merges all search path lists into one list and send it to HeaderSearch.
110   void Realize(const LangOptions &Lang);
111 };
112 
113 }  // end anonymous namespace.
114 
115 static bool CanPrefixSysroot(StringRef Path) {
116 #if defined(_WIN32)
117   return !Path.empty() && llvm::sys::path::is_separator(Path[0]);
118 #else
119   return llvm::sys::path::is_absolute(Path);
120 #endif
121 }
122 
123 bool InitHeaderSearch::AddPath(const Twine &Path, IncludeDirGroup Group,
124                                bool isFramework,
125                                std::optional<unsigned> UserEntryIdx) {
126   // Add the path with sysroot prepended, if desired and this is a system header
127   // group.
128   if (HasSysroot) {
129     SmallString<256> MappedPathStorage;
130     StringRef MappedPathStr = Path.toStringRef(MappedPathStorage);
131     if (CanPrefixSysroot(MappedPathStr)) {
132       return AddUnmappedPath(IncludeSysroot + Path, Group, isFramework,
133                              UserEntryIdx);
134     }
135   }
136 
137   return AddUnmappedPath(Path, Group, isFramework, UserEntryIdx);
138 }
139 
140 bool InitHeaderSearch::AddUnmappedPath(const Twine &Path, IncludeDirGroup Group,
141                                        bool isFramework,
142                                        std::optional<unsigned> UserEntryIdx) {
143   assert(!Path.isTriviallyEmpty() && "can't handle empty path here");
144 
145   FileManager &FM = Headers.getFileMgr();
146   SmallString<256> MappedPathStorage;
147   StringRef MappedPathStr = Path.toStringRef(MappedPathStorage);
148 
149   // If use system headers while cross-compiling, emit the warning.
150   if (HasSysroot && (MappedPathStr.startswith("/usr/include") ||
151                      MappedPathStr.startswith("/usr/local/include"))) {
152     Headers.getDiags().Report(diag::warn_poison_system_directories)
153         << MappedPathStr;
154   }
155 
156   // Compute the DirectoryLookup type.
157   SrcMgr::CharacteristicKind Type;
158   if (Group == Quoted || Group == Angled || Group == IndexHeaderMap) {
159     Type = SrcMgr::C_User;
160   } else if (Group == ExternCSystem) {
161     Type = SrcMgr::C_ExternCSystem;
162   } else {
163     Type = SrcMgr::C_System;
164   }
165 
166   // If the directory exists, add it.
167   if (auto DE = FM.getOptionalDirectoryRef(MappedPathStr)) {
168     IncludePath.emplace_back(Group, DirectoryLookup(*DE, Type, isFramework),
169                              UserEntryIdx);
170     return true;
171   }
172 
173   // Check to see if this is an apple-style headermap (which are not allowed to
174   // be frameworks).
175   if (!isFramework) {
176     if (auto FE = FM.getFile(MappedPathStr)) {
177       if (const HeaderMap *HM = Headers.CreateHeaderMap(*FE)) {
178         // It is a headermap, add it to the search path.
179         IncludePath.emplace_back(
180             Group, DirectoryLookup(HM, Type, Group == IndexHeaderMap),
181             UserEntryIdx);
182         return true;
183       }
184     }
185   }
186 
187   if (Verbose)
188     llvm::errs() << "ignoring nonexistent directory \""
189                  << MappedPathStr << "\"\n";
190   return false;
191 }
192 
193 bool InitHeaderSearch::AddGnuCPlusPlusIncludePaths(StringRef Base,
194                                                    StringRef ArchDir,
195                                                    StringRef Dir32,
196                                                    StringRef Dir64,
197                                                    const llvm::Triple &triple) {
198   // Add the base dir
199   bool IsBaseFound = AddPath(Base, CXXSystem, false);
200 
201   // Add the multilib dirs
202   llvm::Triple::ArchType arch = triple.getArch();
203   bool is64bit = arch == llvm::Triple::ppc64 || arch == llvm::Triple::x86_64;
204   if (is64bit)
205     AddPath(Base + "/" + ArchDir + "/" + Dir64, CXXSystem, false);
206   else
207     AddPath(Base + "/" + ArchDir + "/" + Dir32, CXXSystem, false);
208 
209   // Add the backward dir
210   AddPath(Base + "/backward", CXXSystem, false);
211   return IsBaseFound;
212 }
213 
214 void InitHeaderSearch::AddMinGWCPlusPlusIncludePaths(StringRef Base,
215                                                      StringRef Arch,
216                                                      StringRef Version) {
217   AddPath(Base + "/" + Arch + "/" + Version + "/include/c++",
218           CXXSystem, false);
219   AddPath(Base + "/" + Arch + "/" + Version + "/include/c++/" + Arch,
220           CXXSystem, false);
221   AddPath(Base + "/" + Arch + "/" + Version + "/include/c++/backward",
222           CXXSystem, false);
223 }
224 
225 void InitHeaderSearch::AddDefaultCIncludePaths(const llvm::Triple &triple,
226                                             const HeaderSearchOptions &HSOpts) {
227   if (!ShouldAddDefaultIncludePaths(triple))
228     llvm_unreachable("Include management is handled in the driver.");
229 
230   llvm::Triple::OSType os = triple.getOS();
231 
232   if (HSOpts.UseStandardSystemIncludes) {
233     switch (os) {
234     case llvm::Triple::CloudABI:
235     case llvm::Triple::NaCl:
236     case llvm::Triple::PS4:
237     case llvm::Triple::PS5:
238     case llvm::Triple::ELFIAMCU:
239       break;
240     case llvm::Triple::Win32:
241       if (triple.getEnvironment() != llvm::Triple::Cygnus)
242         break;
243       [[fallthrough]];
244     default:
245       // FIXME: temporary hack: hard-coded paths.
246       AddPath("/usr/local/include", System, false);
247       break;
248     }
249   }
250 
251   // Builtin includes use #include_next directives and should be positioned
252   // just prior C include dirs.
253   if (HSOpts.UseBuiltinIncludes) {
254     // Ignore the sys root, we *always* look for clang headers relative to
255     // supplied path.
256     SmallString<128> P = StringRef(HSOpts.ResourceDir);
257     llvm::sys::path::append(P, "include");
258     AddUnmappedPath(P, ExternCSystem, false);
259   }
260 
261   // All remaining additions are for system include directories, early exit if
262   // we aren't using them.
263   if (!HSOpts.UseStandardSystemIncludes)
264     return;
265 
266   // Add dirs specified via 'configure --with-c-include-dirs'.
267   StringRef CIncludeDirs(C_INCLUDE_DIRS);
268   if (CIncludeDirs != "") {
269     SmallVector<StringRef, 5> dirs;
270     CIncludeDirs.split(dirs, ":");
271     for (StringRef dir : dirs)
272       AddPath(dir, ExternCSystem, false);
273     return;
274   }
275 
276   switch (os) {
277   case llvm::Triple::CloudABI: {
278     // <sysroot>/<triple>/include
279     SmallString<128> P = StringRef(HSOpts.ResourceDir);
280     llvm::sys::path::append(P, "../../..", triple.str(), "include");
281     AddPath(P, System, false);
282     break;
283   }
284 
285   case llvm::Triple::Haiku:
286     AddPath("/boot/system/non-packaged/develop/headers", System, false);
287     AddPath("/boot/system/develop/headers/os", System, false);
288     AddPath("/boot/system/develop/headers/os/app", System, false);
289     AddPath("/boot/system/develop/headers/os/arch", System, false);
290     AddPath("/boot/system/develop/headers/os/device", System, false);
291     AddPath("/boot/system/develop/headers/os/drivers", System, false);
292     AddPath("/boot/system/develop/headers/os/game", System, false);
293     AddPath("/boot/system/develop/headers/os/interface", System, false);
294     AddPath("/boot/system/develop/headers/os/kernel", System, false);
295     AddPath("/boot/system/develop/headers/os/locale", System, false);
296     AddPath("/boot/system/develop/headers/os/mail", System, false);
297     AddPath("/boot/system/develop/headers/os/media", System, false);
298     AddPath("/boot/system/develop/headers/os/midi", System, false);
299     AddPath("/boot/system/develop/headers/os/midi2", System, false);
300     AddPath("/boot/system/develop/headers/os/net", System, false);
301     AddPath("/boot/system/develop/headers/os/opengl", System, false);
302     AddPath("/boot/system/develop/headers/os/storage", System, false);
303     AddPath("/boot/system/develop/headers/os/support", System, false);
304     AddPath("/boot/system/develop/headers/os/translation", System, false);
305     AddPath("/boot/system/develop/headers/os/add-ons/graphics", System, false);
306     AddPath("/boot/system/develop/headers/os/add-ons/input_server", System, false);
307     AddPath("/boot/system/develop/headers/os/add-ons/mail_daemon", System, false);
308     AddPath("/boot/system/develop/headers/os/add-ons/registrar", System, false);
309     AddPath("/boot/system/develop/headers/os/add-ons/screen_saver", System, false);
310     AddPath("/boot/system/develop/headers/os/add-ons/tracker", System, false);
311     AddPath("/boot/system/develop/headers/os/be_apps/Deskbar", System, false);
312     AddPath("/boot/system/develop/headers/os/be_apps/NetPositive", System, false);
313     AddPath("/boot/system/develop/headers/os/be_apps/Tracker", System, false);
314     AddPath("/boot/system/develop/headers/3rdparty", System, false);
315     AddPath("/boot/system/develop/headers/bsd", System, false);
316     AddPath("/boot/system/develop/headers/glibc", System, false);
317     AddPath("/boot/system/develop/headers/posix", System, false);
318     AddPath("/boot/system/develop/headers",  System, false);
319     break;
320   case llvm::Triple::RTEMS:
321     break;
322   case llvm::Triple::Win32:
323     switch (triple.getEnvironment()) {
324     default: llvm_unreachable("Include management is handled in the driver.");
325     case llvm::Triple::Cygnus:
326       AddPath("/usr/include/w32api", System, false);
327       break;
328     case llvm::Triple::GNU:
329       break;
330     }
331     break;
332   default:
333     break;
334   }
335 
336   switch (os) {
337   case llvm::Triple::CloudABI:
338   case llvm::Triple::RTEMS:
339   case llvm::Triple::NaCl:
340   case llvm::Triple::ELFIAMCU:
341     break;
342   case llvm::Triple::PS4:
343   case llvm::Triple::PS5: {
344     // <isysroot> gets prepended later in AddPath().
345     std::string BaseSDKPath;
346     if (!HasSysroot) {
347       const char *EnvVar = (os == llvm::Triple::PS4) ? "SCE_ORBIS_SDK_DIR"
348                                                      : "SCE_PROSPERO_SDK_DIR";
349       const char *envValue = getenv(EnvVar);
350       if (envValue)
351         BaseSDKPath = envValue;
352       else {
353         // HSOpts.ResourceDir variable contains the location of Clang's
354         // resource files.
355         // Assuming that Clang is configured for PS4 without
356         // --with-clang-resource-dir option, the location of Clang's resource
357         // files is <SDK_DIR>/host_tools/lib/clang
358         SmallString<128> P = StringRef(HSOpts.ResourceDir);
359         llvm::sys::path::append(P, "../../..");
360         BaseSDKPath = std::string(P.str());
361       }
362     }
363     AddPath(BaseSDKPath + "/target/include", System, false);
364     AddPath(BaseSDKPath + "/target/include_common", System, false);
365     break;
366   }
367   default:
368     AddPath("/usr/include", ExternCSystem, false);
369     break;
370   }
371 }
372 
373 void InitHeaderSearch::AddDefaultCPlusPlusIncludePaths(
374     const LangOptions &LangOpts, const llvm::Triple &triple,
375     const HeaderSearchOptions &HSOpts) {
376   if (!ShouldAddDefaultIncludePaths(triple))
377     llvm_unreachable("Include management is handled in the driver.");
378 
379   // FIXME: temporary hack: hard-coded paths.
380   llvm::Triple::OSType os = triple.getOS();
381   switch (os) {
382   case llvm::Triple::Win32:
383     switch (triple.getEnvironment()) {
384     default: llvm_unreachable("Include management is handled in the driver.");
385     case llvm::Triple::Cygnus:
386       // Cygwin-1.7
387       AddMinGWCPlusPlusIncludePaths("/usr/lib/gcc", "i686-pc-cygwin", "4.7.3");
388       AddMinGWCPlusPlusIncludePaths("/usr/lib/gcc", "i686-pc-cygwin", "4.5.3");
389       AddMinGWCPlusPlusIncludePaths("/usr/lib/gcc", "i686-pc-cygwin", "4.3.4");
390       // g++-4 / Cygwin-1.5
391       AddMinGWCPlusPlusIncludePaths("/usr/lib/gcc", "i686-pc-cygwin", "4.3.2");
392       break;
393     }
394     break;
395   case llvm::Triple::DragonFly:
396     AddPath("/usr/include/c++/5.0", CXXSystem, false);
397     break;
398   case llvm::Triple::Minix:
399     AddGnuCPlusPlusIncludePaths("/usr/gnu/include/c++/4.4.3",
400                                 "", "", "", triple);
401     break;
402   default:
403     break;
404   }
405 }
406 
407 bool InitHeaderSearch::ShouldAddDefaultIncludePaths(
408     const llvm::Triple &triple) {
409   switch (triple.getOS()) {
410   case llvm::Triple::AIX:
411   case llvm::Triple::Emscripten:
412   case llvm::Triple::FreeBSD:
413   case llvm::Triple::NetBSD:
414   case llvm::Triple::OpenBSD:
415   case llvm::Triple::Fuchsia:
416   case llvm::Triple::Hurd:
417   case llvm::Triple::Linux:
418   case llvm::Triple::Solaris:
419   case llvm::Triple::WASI:
420     return false;
421 
422   case llvm::Triple::Win32:
423     if (triple.getEnvironment() != llvm::Triple::Cygnus ||
424         triple.isOSBinFormatMachO())
425       return false;
426     break;
427 
428   case llvm::Triple::UnknownOS:
429     if (triple.isWasm())
430       return false;
431     break;
432 
433   default:
434     break;
435   }
436 
437   return true; // Everything else uses AddDefaultIncludePaths().
438 }
439 
440 void InitHeaderSearch::AddDefaultIncludePaths(
441     const LangOptions &Lang, const llvm::Triple &triple,
442     const HeaderSearchOptions &HSOpts) {
443   // NB: This code path is going away. All of the logic is moving into the
444   // driver which has the information necessary to do target-specific
445   // selections of default include paths. Each target which moves there will be
446   // exempted from this logic in ShouldAddDefaultIncludePaths() until we can
447   // delete the entire pile of code.
448   if (!ShouldAddDefaultIncludePaths(triple))
449     return;
450 
451   // NOTE: some additional header search logic is handled in the driver for
452   // Darwin.
453   if (triple.isOSDarwin()) {
454     if (HSOpts.UseStandardSystemIncludes) {
455       // Add the default framework include paths on Darwin.
456       if (triple.isDriverKit()) {
457         AddPath("/System/DriverKit/System/Library/Frameworks", System, true);
458       } else {
459         AddPath("/System/Library/Frameworks", System, true);
460         AddPath("/Library/Frameworks", System, true);
461       }
462     }
463     return;
464   }
465 
466   if (Lang.CPlusPlus && !Lang.AsmPreprocessor &&
467       HSOpts.UseStandardCXXIncludes && HSOpts.UseStandardSystemIncludes) {
468     if (HSOpts.UseLibcxx) {
469       AddPath("/usr/include/c++/v1", CXXSystem, false);
470     } else {
471       AddDefaultCPlusPlusIncludePaths(Lang, triple, HSOpts);
472     }
473   }
474 
475   AddDefaultCIncludePaths(triple, HSOpts);
476 }
477 
478 /// If there are duplicate directory entries in the specified search list,
479 /// remove the later (dead) ones.  Returns the number of non-system headers
480 /// removed, which is used to update NumAngled.
481 static unsigned RemoveDuplicates(std::vector<DirectoryLookupInfo> &SearchList,
482                                  unsigned First, bool Verbose) {
483   llvm::SmallPtrSet<const DirectoryEntry *, 8> SeenDirs;
484   llvm::SmallPtrSet<const DirectoryEntry *, 8> SeenFrameworkDirs;
485   llvm::SmallPtrSet<const HeaderMap *, 8> SeenHeaderMaps;
486   unsigned NonSystemRemoved = 0;
487   for (unsigned i = First; i != SearchList.size(); ++i) {
488     unsigned DirToRemove = i;
489 
490     const DirectoryLookup &CurEntry = SearchList[i].Lookup;
491 
492     if (CurEntry.isNormalDir()) {
493       // If this isn't the first time we've seen this dir, remove it.
494       if (SeenDirs.insert(CurEntry.getDir()).second)
495         continue;
496     } else if (CurEntry.isFramework()) {
497       // If this isn't the first time we've seen this framework dir, remove it.
498       if (SeenFrameworkDirs.insert(CurEntry.getFrameworkDir()).second)
499         continue;
500     } else {
501       assert(CurEntry.isHeaderMap() && "Not a headermap or normal dir?");
502       // If this isn't the first time we've seen this headermap, remove it.
503       if (SeenHeaderMaps.insert(CurEntry.getHeaderMap()).second)
504         continue;
505     }
506 
507     // If we have a normal #include dir/framework/headermap that is shadowed
508     // later in the chain by a system include location, we actually want to
509     // ignore the user's request and drop the user dir... keeping the system
510     // dir.  This is weird, but required to emulate GCC's search path correctly.
511     //
512     // Since dupes of system dirs are rare, just rescan to find the original
513     // that we're nuking instead of using a DenseMap.
514     if (CurEntry.getDirCharacteristic() != SrcMgr::C_User) {
515       // Find the dir that this is the same of.
516       unsigned FirstDir;
517       for (FirstDir = First;; ++FirstDir) {
518         assert(FirstDir != i && "Didn't find dupe?");
519 
520         const DirectoryLookup &SearchEntry = SearchList[FirstDir].Lookup;
521 
522         // If these are different lookup types, then they can't be the dupe.
523         if (SearchEntry.getLookupType() != CurEntry.getLookupType())
524           continue;
525 
526         bool isSame;
527         if (CurEntry.isNormalDir())
528           isSame = SearchEntry.getDir() == CurEntry.getDir();
529         else if (CurEntry.isFramework())
530           isSame = SearchEntry.getFrameworkDir() == CurEntry.getFrameworkDir();
531         else {
532           assert(CurEntry.isHeaderMap() && "Not a headermap or normal dir?");
533           isSame = SearchEntry.getHeaderMap() == CurEntry.getHeaderMap();
534         }
535 
536         if (isSame)
537           break;
538       }
539 
540       // If the first dir in the search path is a non-system dir, zap it
541       // instead of the system one.
542       if (SearchList[FirstDir].Lookup.getDirCharacteristic() == SrcMgr::C_User)
543         DirToRemove = FirstDir;
544     }
545 
546     if (Verbose) {
547       llvm::errs() << "ignoring duplicate directory \""
548                    << CurEntry.getName() << "\"\n";
549       if (DirToRemove != i)
550         llvm::errs() << "  as it is a non-system directory that duplicates "
551                      << "a system directory\n";
552     }
553     if (DirToRemove != i)
554       ++NonSystemRemoved;
555 
556     // This is reached if the current entry is a duplicate.  Remove the
557     // DirToRemove (usually the current dir).
558     SearchList.erase(SearchList.begin()+DirToRemove);
559     --i;
560   }
561   return NonSystemRemoved;
562 }
563 
564 /// Extract DirectoryLookups from DirectoryLookupInfos.
565 static std::vector<DirectoryLookup>
566 extractLookups(const std::vector<DirectoryLookupInfo> &Infos) {
567   std::vector<DirectoryLookup> Lookups;
568   Lookups.reserve(Infos.size());
569   llvm::transform(Infos, std::back_inserter(Lookups),
570                   [](const DirectoryLookupInfo &Info) { return Info.Lookup; });
571   return Lookups;
572 }
573 
574 /// Collect the mapping between indices of DirectoryLookups and UserEntries.
575 static llvm::DenseMap<unsigned, unsigned>
576 mapToUserEntries(const std::vector<DirectoryLookupInfo> &Infos) {
577   llvm::DenseMap<unsigned, unsigned> LookupsToUserEntries;
578   for (unsigned I = 0, E = Infos.size(); I < E; ++I) {
579     // Check whether this DirectoryLookup maps to a HeaderSearch::UserEntry.
580     if (Infos[I].UserEntryIdx)
581       LookupsToUserEntries.insert({I, *Infos[I].UserEntryIdx});
582   }
583   return LookupsToUserEntries;
584 }
585 
586 void InitHeaderSearch::Realize(const LangOptions &Lang) {
587   // Concatenate ANGLE+SYSTEM+AFTER chains together into SearchList.
588   std::vector<DirectoryLookupInfo> SearchList;
589   SearchList.reserve(IncludePath.size());
590 
591   // Quoted arguments go first.
592   for (auto &Include : IncludePath)
593     if (Include.Group == Quoted)
594       SearchList.push_back(Include);
595 
596   // Deduplicate and remember index.
597   RemoveDuplicates(SearchList, 0, Verbose);
598   unsigned NumQuoted = SearchList.size();
599 
600   for (auto &Include : IncludePath)
601     if (Include.Group == Angled || Include.Group == IndexHeaderMap)
602       SearchList.push_back(Include);
603 
604   RemoveDuplicates(SearchList, NumQuoted, Verbose);
605   unsigned NumAngled = SearchList.size();
606 
607   for (auto &Include : IncludePath)
608     if (Include.Group == System || Include.Group == ExternCSystem ||
609         (!Lang.ObjC && !Lang.CPlusPlus && Include.Group == CSystem) ||
610         (/*FIXME !Lang.ObjC && */ Lang.CPlusPlus &&
611          Include.Group == CXXSystem) ||
612         (Lang.ObjC && !Lang.CPlusPlus && Include.Group == ObjCSystem) ||
613         (Lang.ObjC && Lang.CPlusPlus && Include.Group == ObjCXXSystem))
614       SearchList.push_back(Include);
615 
616   for (auto &Include : IncludePath)
617     if (Include.Group == After)
618       SearchList.push_back(Include);
619 
620   // Remove duplicates across both the Angled and System directories.  GCC does
621   // this and failing to remove duplicates across these two groups breaks
622   // #include_next.
623   unsigned NonSystemRemoved = RemoveDuplicates(SearchList, NumQuoted, Verbose);
624   NumAngled -= NonSystemRemoved;
625 
626   bool DontSearchCurDir = false;  // TODO: set to true if -I- is set?
627   Headers.SetSearchPaths(extractLookups(SearchList), NumQuoted, NumAngled,
628                          DontSearchCurDir, mapToUserEntries(SearchList));
629 
630   Headers.SetSystemHeaderPrefixes(SystemHeaderPrefixes);
631 
632   // If verbose, print the list of directories that will be searched.
633   if (Verbose) {
634     llvm::errs() << "#include \"...\" search starts here:\n";
635     for (unsigned i = 0, e = SearchList.size(); i != e; ++i) {
636       if (i == NumQuoted)
637         llvm::errs() << "#include <...> search starts here:\n";
638       StringRef Name = SearchList[i].Lookup.getName();
639       const char *Suffix;
640       if (SearchList[i].Lookup.isNormalDir())
641         Suffix = "";
642       else if (SearchList[i].Lookup.isFramework())
643         Suffix = " (framework directory)";
644       else {
645         assert(SearchList[i].Lookup.isHeaderMap() && "Unknown DirectoryLookup");
646         Suffix = " (headermap)";
647       }
648       llvm::errs() << " " << Name << Suffix << "\n";
649     }
650     llvm::errs() << "End of search list.\n";
651   }
652 }
653 
654 void clang::ApplyHeaderSearchOptions(HeaderSearch &HS,
655                                      const HeaderSearchOptions &HSOpts,
656                                      const LangOptions &Lang,
657                                      const llvm::Triple &Triple) {
658   InitHeaderSearch Init(HS, HSOpts.Verbose, HSOpts.Sysroot);
659 
660   // Add the user defined entries.
661   for (unsigned i = 0, e = HSOpts.UserEntries.size(); i != e; ++i) {
662     const HeaderSearchOptions::Entry &E = HSOpts.UserEntries[i];
663     if (E.IgnoreSysRoot) {
664       Init.AddUnmappedPath(E.Path, E.Group, E.IsFramework, i);
665     } else {
666       Init.AddPath(E.Path, E.Group, E.IsFramework, i);
667     }
668   }
669 
670   Init.AddDefaultIncludePaths(Lang, Triple, HSOpts);
671 
672   for (unsigned i = 0, e = HSOpts.SystemHeaderPrefixes.size(); i != e; ++i)
673     Init.AddSystemHeaderPrefix(HSOpts.SystemHeaderPrefixes[i].Prefix,
674                                HSOpts.SystemHeaderPrefixes[i].IsSystemHeader);
675 
676   if (HSOpts.UseBuiltinIncludes) {
677     // Set up the builtin include directory in the module map.
678     SmallString<128> P = StringRef(HSOpts.ResourceDir);
679     llvm::sys::path::append(P, "include");
680     if (auto Dir = HS.getFileMgr().getDirectory(P))
681       HS.getModuleMap().setBuiltinIncludeDir(*Dir);
682   }
683 
684   Init.Realize(Lang);
685 }
686