xref: /freebsd/contrib/llvm-project/clang/lib/Lex/PPMacroExpansion.cpp (revision ec0ea6efa1ad229d75c394c1a9b9cac33af2b1d3)
1 //===--- PPMacroExpansion.cpp - Top level Macro Expansion -----------------===//
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 top level handling of macro expansion for the
10 // preprocessor.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "clang/Basic/Attributes.h"
15 #include "clang/Basic/Builtins.h"
16 #include "clang/Basic/FileManager.h"
17 #include "clang/Basic/IdentifierTable.h"
18 #include "clang/Basic/LLVM.h"
19 #include "clang/Basic/LangOptions.h"
20 #include "clang/Basic/ObjCRuntime.h"
21 #include "clang/Basic/SourceLocation.h"
22 #include "clang/Basic/TargetInfo.h"
23 #include "clang/Lex/CodeCompletionHandler.h"
24 #include "clang/Lex/DirectoryLookup.h"
25 #include "clang/Lex/ExternalPreprocessorSource.h"
26 #include "clang/Lex/HeaderSearch.h"
27 #include "clang/Lex/LexDiagnostic.h"
28 #include "clang/Lex/LiteralSupport.h"
29 #include "clang/Lex/MacroArgs.h"
30 #include "clang/Lex/MacroInfo.h"
31 #include "clang/Lex/Preprocessor.h"
32 #include "clang/Lex/PreprocessorLexer.h"
33 #include "clang/Lex/PreprocessorOptions.h"
34 #include "clang/Lex/Token.h"
35 #include "llvm/ADT/ArrayRef.h"
36 #include "llvm/ADT/DenseMap.h"
37 #include "llvm/ADT/DenseSet.h"
38 #include "llvm/ADT/FoldingSet.h"
39 #include "llvm/ADT/None.h"
40 #include "llvm/ADT/Optional.h"
41 #include "llvm/ADT/STLExtras.h"
42 #include "llvm/ADT/SmallString.h"
43 #include "llvm/ADT/SmallVector.h"
44 #include "llvm/ADT/StringRef.h"
45 #include "llvm/ADT/StringSwitch.h"
46 #include "llvm/Support/Casting.h"
47 #include "llvm/Support/ErrorHandling.h"
48 #include "llvm/Support/Format.h"
49 #include "llvm/Support/Path.h"
50 #include "llvm/Support/raw_ostream.h"
51 #include <algorithm>
52 #include <cassert>
53 #include <cstddef>
54 #include <cstring>
55 #include <ctime>
56 #include <string>
57 #include <tuple>
58 #include <utility>
59 
60 using namespace clang;
61 
62 MacroDirective *
63 Preprocessor::getLocalMacroDirectiveHistory(const IdentifierInfo *II) const {
64   if (!II->hadMacroDefinition())
65     return nullptr;
66   auto Pos = CurSubmoduleState->Macros.find(II);
67   return Pos == CurSubmoduleState->Macros.end() ? nullptr
68                                                 : Pos->second.getLatest();
69 }
70 
71 void Preprocessor::appendMacroDirective(IdentifierInfo *II, MacroDirective *MD){
72   assert(MD && "MacroDirective should be non-zero!");
73   assert(!MD->getPrevious() && "Already attached to a MacroDirective history.");
74 
75   MacroState &StoredMD = CurSubmoduleState->Macros[II];
76   auto *OldMD = StoredMD.getLatest();
77   MD->setPrevious(OldMD);
78   StoredMD.setLatest(MD);
79   StoredMD.overrideActiveModuleMacros(*this, II);
80 
81   if (needModuleMacros()) {
82     // Track that we created a new macro directive, so we know we should
83     // consider building a ModuleMacro for it when we get to the end of
84     // the module.
85     PendingModuleMacroNames.push_back(II);
86   }
87 
88   // Set up the identifier as having associated macro history.
89   II->setHasMacroDefinition(true);
90   if (!MD->isDefined() && LeafModuleMacros.find(II) == LeafModuleMacros.end())
91     II->setHasMacroDefinition(false);
92   if (II->isFromAST())
93     II->setChangedSinceDeserialization();
94 }
95 
96 void Preprocessor::setLoadedMacroDirective(IdentifierInfo *II,
97                                            MacroDirective *ED,
98                                            MacroDirective *MD) {
99   // Normally, when a macro is defined, it goes through appendMacroDirective()
100   // above, which chains a macro to previous defines, undefs, etc.
101   // However, in a pch, the whole macro history up to the end of the pch is
102   // stored, so ASTReader goes through this function instead.
103   // However, built-in macros are already registered in the Preprocessor
104   // ctor, and ASTWriter stops writing the macro chain at built-in macros,
105   // so in that case the chain from the pch needs to be spliced to the existing
106   // built-in.
107 
108   assert(II && MD);
109   MacroState &StoredMD = CurSubmoduleState->Macros[II];
110 
111   if (auto *OldMD = StoredMD.getLatest()) {
112     // shouldIgnoreMacro() in ASTWriter also stops at macros from the
113     // predefines buffer in module builds. However, in module builds, modules
114     // are loaded completely before predefines are processed, so StoredMD
115     // will be nullptr for them when they're loaded. StoredMD should only be
116     // non-nullptr for builtins read from a pch file.
117     assert(OldMD->getMacroInfo()->isBuiltinMacro() &&
118            "only built-ins should have an entry here");
119     assert(!OldMD->getPrevious() && "builtin should only have a single entry");
120     ED->setPrevious(OldMD);
121     StoredMD.setLatest(MD);
122   } else {
123     StoredMD = MD;
124   }
125 
126   // Setup the identifier as having associated macro history.
127   II->setHasMacroDefinition(true);
128   if (!MD->isDefined() && LeafModuleMacros.find(II) == LeafModuleMacros.end())
129     II->setHasMacroDefinition(false);
130 }
131 
132 ModuleMacro *Preprocessor::addModuleMacro(Module *Mod, IdentifierInfo *II,
133                                           MacroInfo *Macro,
134                                           ArrayRef<ModuleMacro *> Overrides,
135                                           bool &New) {
136   llvm::FoldingSetNodeID ID;
137   ModuleMacro::Profile(ID, Mod, II);
138 
139   void *InsertPos;
140   if (auto *MM = ModuleMacros.FindNodeOrInsertPos(ID, InsertPos)) {
141     New = false;
142     return MM;
143   }
144 
145   auto *MM = ModuleMacro::create(*this, Mod, II, Macro, Overrides);
146   ModuleMacros.InsertNode(MM, InsertPos);
147 
148   // Each overridden macro is now overridden by one more macro.
149   bool HidAny = false;
150   for (auto *O : Overrides) {
151     HidAny |= (O->NumOverriddenBy == 0);
152     ++O->NumOverriddenBy;
153   }
154 
155   // If we were the first overrider for any macro, it's no longer a leaf.
156   auto &LeafMacros = LeafModuleMacros[II];
157   if (HidAny) {
158     LeafMacros.erase(std::remove_if(LeafMacros.begin(), LeafMacros.end(),
159                                     [](ModuleMacro *MM) {
160                                       return MM->NumOverriddenBy != 0;
161                                     }),
162                      LeafMacros.end());
163   }
164 
165   // The new macro is always a leaf macro.
166   LeafMacros.push_back(MM);
167   // The identifier now has defined macros (that may or may not be visible).
168   II->setHasMacroDefinition(true);
169 
170   New = true;
171   return MM;
172 }
173 
174 ModuleMacro *Preprocessor::getModuleMacro(Module *Mod,
175                                           const IdentifierInfo *II) {
176   llvm::FoldingSetNodeID ID;
177   ModuleMacro::Profile(ID, Mod, II);
178 
179   void *InsertPos;
180   return ModuleMacros.FindNodeOrInsertPos(ID, InsertPos);
181 }
182 
183 void Preprocessor::updateModuleMacroInfo(const IdentifierInfo *II,
184                                          ModuleMacroInfo &Info) {
185   assert(Info.ActiveModuleMacrosGeneration !=
186              CurSubmoduleState->VisibleModules.getGeneration() &&
187          "don't need to update this macro name info");
188   Info.ActiveModuleMacrosGeneration =
189       CurSubmoduleState->VisibleModules.getGeneration();
190 
191   auto Leaf = LeafModuleMacros.find(II);
192   if (Leaf == LeafModuleMacros.end()) {
193     // No imported macros at all: nothing to do.
194     return;
195   }
196 
197   Info.ActiveModuleMacros.clear();
198 
199   // Every macro that's locally overridden is overridden by a visible macro.
200   llvm::DenseMap<ModuleMacro *, int> NumHiddenOverrides;
201   for (auto *O : Info.OverriddenMacros)
202     NumHiddenOverrides[O] = -1;
203 
204   // Collect all macros that are not overridden by a visible macro.
205   llvm::SmallVector<ModuleMacro *, 16> Worklist;
206   for (auto *LeafMM : Leaf->second) {
207     assert(LeafMM->getNumOverridingMacros() == 0 && "leaf macro overridden");
208     if (NumHiddenOverrides.lookup(LeafMM) == 0)
209       Worklist.push_back(LeafMM);
210   }
211   while (!Worklist.empty()) {
212     auto *MM = Worklist.pop_back_val();
213     if (CurSubmoduleState->VisibleModules.isVisible(MM->getOwningModule())) {
214       // We only care about collecting definitions; undefinitions only act
215       // to override other definitions.
216       if (MM->getMacroInfo())
217         Info.ActiveModuleMacros.push_back(MM);
218     } else {
219       for (auto *O : MM->overrides())
220         if ((unsigned)++NumHiddenOverrides[O] == O->getNumOverridingMacros())
221           Worklist.push_back(O);
222     }
223   }
224   // Our reverse postorder walk found the macros in reverse order.
225   std::reverse(Info.ActiveModuleMacros.begin(), Info.ActiveModuleMacros.end());
226 
227   // Determine whether the macro name is ambiguous.
228   MacroInfo *MI = nullptr;
229   bool IsSystemMacro = true;
230   bool IsAmbiguous = false;
231   if (auto *MD = Info.MD) {
232     while (MD && isa<VisibilityMacroDirective>(MD))
233       MD = MD->getPrevious();
234     if (auto *DMD = dyn_cast_or_null<DefMacroDirective>(MD)) {
235       MI = DMD->getInfo();
236       IsSystemMacro &= SourceMgr.isInSystemHeader(DMD->getLocation());
237     }
238   }
239   for (auto *Active : Info.ActiveModuleMacros) {
240     auto *NewMI = Active->getMacroInfo();
241 
242     // Before marking the macro as ambiguous, check if this is a case where
243     // both macros are in system headers. If so, we trust that the system
244     // did not get it wrong. This also handles cases where Clang's own
245     // headers have a different spelling of certain system macros:
246     //   #define LONG_MAX __LONG_MAX__ (clang's limits.h)
247     //   #define LONG_MAX 0x7fffffffffffffffL (system's limits.h)
248     //
249     // FIXME: Remove the defined-in-system-headers check. clang's limits.h
250     // overrides the system limits.h's macros, so there's no conflict here.
251     if (MI && NewMI != MI &&
252         !MI->isIdenticalTo(*NewMI, *this, /*Syntactically=*/true))
253       IsAmbiguous = true;
254     IsSystemMacro &= Active->getOwningModule()->IsSystem ||
255                      SourceMgr.isInSystemHeader(NewMI->getDefinitionLoc());
256     MI = NewMI;
257   }
258   Info.IsAmbiguous = IsAmbiguous && !IsSystemMacro;
259 }
260 
261 void Preprocessor::dumpMacroInfo(const IdentifierInfo *II) {
262   ArrayRef<ModuleMacro*> Leaf;
263   auto LeafIt = LeafModuleMacros.find(II);
264   if (LeafIt != LeafModuleMacros.end())
265     Leaf = LeafIt->second;
266   const MacroState *State = nullptr;
267   auto Pos = CurSubmoduleState->Macros.find(II);
268   if (Pos != CurSubmoduleState->Macros.end())
269     State = &Pos->second;
270 
271   llvm::errs() << "MacroState " << State << " " << II->getNameStart();
272   if (State && State->isAmbiguous(*this, II))
273     llvm::errs() << " ambiguous";
274   if (State && !State->getOverriddenMacros().empty()) {
275     llvm::errs() << " overrides";
276     for (auto *O : State->getOverriddenMacros())
277       llvm::errs() << " " << O->getOwningModule()->getFullModuleName();
278   }
279   llvm::errs() << "\n";
280 
281   // Dump local macro directives.
282   for (auto *MD = State ? State->getLatest() : nullptr; MD;
283        MD = MD->getPrevious()) {
284     llvm::errs() << " ";
285     MD->dump();
286   }
287 
288   // Dump module macros.
289   llvm::DenseSet<ModuleMacro*> Active;
290   for (auto *MM : State ? State->getActiveModuleMacros(*this, II) : None)
291     Active.insert(MM);
292   llvm::DenseSet<ModuleMacro*> Visited;
293   llvm::SmallVector<ModuleMacro *, 16> Worklist(Leaf.begin(), Leaf.end());
294   while (!Worklist.empty()) {
295     auto *MM = Worklist.pop_back_val();
296     llvm::errs() << " ModuleMacro " << MM << " "
297                  << MM->getOwningModule()->getFullModuleName();
298     if (!MM->getMacroInfo())
299       llvm::errs() << " undef";
300 
301     if (Active.count(MM))
302       llvm::errs() << " active";
303     else if (!CurSubmoduleState->VisibleModules.isVisible(
304                  MM->getOwningModule()))
305       llvm::errs() << " hidden";
306     else if (MM->getMacroInfo())
307       llvm::errs() << " overridden";
308 
309     if (!MM->overrides().empty()) {
310       llvm::errs() << " overrides";
311       for (auto *O : MM->overrides()) {
312         llvm::errs() << " " << O->getOwningModule()->getFullModuleName();
313         if (Visited.insert(O).second)
314           Worklist.push_back(O);
315       }
316     }
317     llvm::errs() << "\n";
318     if (auto *MI = MM->getMacroInfo()) {
319       llvm::errs() << "  ";
320       MI->dump();
321       llvm::errs() << "\n";
322     }
323   }
324 }
325 
326 /// RegisterBuiltinMacro - Register the specified identifier in the identifier
327 /// table and mark it as a builtin macro to be expanded.
328 static IdentifierInfo *RegisterBuiltinMacro(Preprocessor &PP, const char *Name){
329   // Get the identifier.
330   IdentifierInfo *Id = PP.getIdentifierInfo(Name);
331 
332   // Mark it as being a macro that is builtin.
333   MacroInfo *MI = PP.AllocateMacroInfo(SourceLocation());
334   MI->setIsBuiltinMacro();
335   PP.appendDefMacroDirective(Id, MI);
336   return Id;
337 }
338 
339 /// RegisterBuiltinMacros - Register builtin macros, such as __LINE__ with the
340 /// identifier table.
341 void Preprocessor::RegisterBuiltinMacros() {
342   Ident__LINE__ = RegisterBuiltinMacro(*this, "__LINE__");
343   Ident__FILE__ = RegisterBuiltinMacro(*this, "__FILE__");
344   Ident__DATE__ = RegisterBuiltinMacro(*this, "__DATE__");
345   Ident__TIME__ = RegisterBuiltinMacro(*this, "__TIME__");
346   Ident__COUNTER__ = RegisterBuiltinMacro(*this, "__COUNTER__");
347   Ident_Pragma  = RegisterBuiltinMacro(*this, "_Pragma");
348 
349   // C++ Standing Document Extensions.
350   if (getLangOpts().CPlusPlus)
351     Ident__has_cpp_attribute =
352         RegisterBuiltinMacro(*this, "__has_cpp_attribute");
353   else
354     Ident__has_cpp_attribute = nullptr;
355 
356   // GCC Extensions.
357   Ident__BASE_FILE__     = RegisterBuiltinMacro(*this, "__BASE_FILE__");
358   Ident__INCLUDE_LEVEL__ = RegisterBuiltinMacro(*this, "__INCLUDE_LEVEL__");
359   Ident__TIMESTAMP__     = RegisterBuiltinMacro(*this, "__TIMESTAMP__");
360 
361   // Microsoft Extensions.
362   if (getLangOpts().MicrosoftExt) {
363     Ident__identifier = RegisterBuiltinMacro(*this, "__identifier");
364     Ident__pragma = RegisterBuiltinMacro(*this, "__pragma");
365   } else {
366     Ident__identifier = nullptr;
367     Ident__pragma = nullptr;
368   }
369 
370   // Clang Extensions.
371   Ident__FILE_NAME__      = RegisterBuiltinMacro(*this, "__FILE_NAME__");
372   Ident__has_feature      = RegisterBuiltinMacro(*this, "__has_feature");
373   Ident__has_extension    = RegisterBuiltinMacro(*this, "__has_extension");
374   Ident__has_builtin      = RegisterBuiltinMacro(*this, "__has_builtin");
375   Ident__has_attribute    = RegisterBuiltinMacro(*this, "__has_attribute");
376   if (!getLangOpts().CPlusPlus)
377     Ident__has_c_attribute = RegisterBuiltinMacro(*this, "__has_c_attribute");
378   else
379     Ident__has_c_attribute = nullptr;
380 
381   Ident__has_declspec = RegisterBuiltinMacro(*this, "__has_declspec_attribute");
382   Ident__has_include      = RegisterBuiltinMacro(*this, "__has_include");
383   Ident__has_include_next = RegisterBuiltinMacro(*this, "__has_include_next");
384   Ident__has_warning      = RegisterBuiltinMacro(*this, "__has_warning");
385   Ident__is_identifier    = RegisterBuiltinMacro(*this, "__is_identifier");
386   Ident__is_target_arch   = RegisterBuiltinMacro(*this, "__is_target_arch");
387   Ident__is_target_vendor = RegisterBuiltinMacro(*this, "__is_target_vendor");
388   Ident__is_target_os     = RegisterBuiltinMacro(*this, "__is_target_os");
389   Ident__is_target_environment =
390       RegisterBuiltinMacro(*this, "__is_target_environment");
391 
392   // Modules.
393   Ident__building_module  = RegisterBuiltinMacro(*this, "__building_module");
394   if (!getLangOpts().CurrentModule.empty())
395     Ident__MODULE__ = RegisterBuiltinMacro(*this, "__MODULE__");
396   else
397     Ident__MODULE__ = nullptr;
398 }
399 
400 /// isTrivialSingleTokenExpansion - Return true if MI, which has a single token
401 /// in its expansion, currently expands to that token literally.
402 static bool isTrivialSingleTokenExpansion(const MacroInfo *MI,
403                                           const IdentifierInfo *MacroIdent,
404                                           Preprocessor &PP) {
405   IdentifierInfo *II = MI->getReplacementToken(0).getIdentifierInfo();
406 
407   // If the token isn't an identifier, it's always literally expanded.
408   if (!II) return true;
409 
410   // If the information about this identifier is out of date, update it from
411   // the external source.
412   if (II->isOutOfDate())
413     PP.getExternalSource()->updateOutOfDateIdentifier(*II);
414 
415   // If the identifier is a macro, and if that macro is enabled, it may be
416   // expanded so it's not a trivial expansion.
417   if (auto *ExpansionMI = PP.getMacroInfo(II))
418     if (ExpansionMI->isEnabled() &&
419         // Fast expanding "#define X X" is ok, because X would be disabled.
420         II != MacroIdent)
421       return false;
422 
423   // If this is an object-like macro invocation, it is safe to trivially expand
424   // it.
425   if (MI->isObjectLike()) return true;
426 
427   // If this is a function-like macro invocation, it's safe to trivially expand
428   // as long as the identifier is not a macro argument.
429   return std::find(MI->param_begin(), MI->param_end(), II) == MI->param_end();
430 }
431 
432 /// isNextPPTokenLParen - Determine whether the next preprocessor token to be
433 /// lexed is a '('.  If so, consume the token and return true, if not, this
434 /// method should have no observable side-effect on the lexed tokens.
435 bool Preprocessor::isNextPPTokenLParen() {
436   // Do some quick tests for rejection cases.
437   unsigned Val;
438   if (CurLexer)
439     Val = CurLexer->isNextPPTokenLParen();
440   else
441     Val = CurTokenLexer->isNextTokenLParen();
442 
443   if (Val == 2) {
444     // We have run off the end.  If it's a source file we don't
445     // examine enclosing ones (C99 5.1.1.2p4).  Otherwise walk up the
446     // macro stack.
447     if (CurPPLexer)
448       return false;
449     for (const IncludeStackInfo &Entry : llvm::reverse(IncludeMacroStack)) {
450       if (Entry.TheLexer)
451         Val = Entry.TheLexer->isNextPPTokenLParen();
452       else
453         Val = Entry.TheTokenLexer->isNextTokenLParen();
454 
455       if (Val != 2)
456         break;
457 
458       // Ran off the end of a source file?
459       if (Entry.ThePPLexer)
460         return false;
461     }
462   }
463 
464   // Okay, if we know that the token is a '(', lex it and return.  Otherwise we
465   // have found something that isn't a '(' or we found the end of the
466   // translation unit.  In either case, return false.
467   return Val == 1;
468 }
469 
470 /// HandleMacroExpandedIdentifier - If an identifier token is read that is to be
471 /// expanded as a macro, handle it and return the next token as 'Identifier'.
472 bool Preprocessor::HandleMacroExpandedIdentifier(Token &Identifier,
473                                                  const MacroDefinition &M) {
474   MacroInfo *MI = M.getMacroInfo();
475 
476   // If this is a macro expansion in the "#if !defined(x)" line for the file,
477   // then the macro could expand to different things in other contexts, we need
478   // to disable the optimization in this case.
479   if (CurPPLexer) CurPPLexer->MIOpt.ExpandedMacro();
480 
481   // If this is a builtin macro, like __LINE__ or _Pragma, handle it specially.
482   if (MI->isBuiltinMacro()) {
483     if (Callbacks)
484       Callbacks->MacroExpands(Identifier, M, Identifier.getLocation(),
485                               /*Args=*/nullptr);
486     ExpandBuiltinMacro(Identifier);
487     return true;
488   }
489 
490   /// Args - If this is a function-like macro expansion, this contains,
491   /// for each macro argument, the list of tokens that were provided to the
492   /// invocation.
493   MacroArgs *Args = nullptr;
494 
495   // Remember where the end of the expansion occurred.  For an object-like
496   // macro, this is the identifier.  For a function-like macro, this is the ')'.
497   SourceLocation ExpansionEnd = Identifier.getLocation();
498 
499   // If this is a function-like macro, read the arguments.
500   if (MI->isFunctionLike()) {
501     // Remember that we are now parsing the arguments to a macro invocation.
502     // Preprocessor directives used inside macro arguments are not portable, and
503     // this enables the warning.
504     InMacroArgs = true;
505     ArgMacro = &Identifier;
506 
507     Args = ReadMacroCallArgumentList(Identifier, MI, ExpansionEnd);
508 
509     // Finished parsing args.
510     InMacroArgs = false;
511     ArgMacro = nullptr;
512 
513     // If there was an error parsing the arguments, bail out.
514     if (!Args) return true;
515 
516     ++NumFnMacroExpanded;
517   } else {
518     ++NumMacroExpanded;
519   }
520 
521   // Notice that this macro has been used.
522   markMacroAsUsed(MI);
523 
524   // Remember where the token is expanded.
525   SourceLocation ExpandLoc = Identifier.getLocation();
526   SourceRange ExpansionRange(ExpandLoc, ExpansionEnd);
527 
528   if (Callbacks) {
529     if (InMacroArgs) {
530       // We can have macro expansion inside a conditional directive while
531       // reading the function macro arguments. To ensure, in that case, that
532       // MacroExpands callbacks still happen in source order, queue this
533       // callback to have it happen after the function macro callback.
534       DelayedMacroExpandsCallbacks.push_back(
535           MacroExpandsInfo(Identifier, M, ExpansionRange));
536     } else {
537       Callbacks->MacroExpands(Identifier, M, ExpansionRange, Args);
538       if (!DelayedMacroExpandsCallbacks.empty()) {
539         for (const MacroExpandsInfo &Info : DelayedMacroExpandsCallbacks) {
540           // FIXME: We lose macro args info with delayed callback.
541           Callbacks->MacroExpands(Info.Tok, Info.MD, Info.Range,
542                                   /*Args=*/nullptr);
543         }
544         DelayedMacroExpandsCallbacks.clear();
545       }
546     }
547   }
548 
549   // If the macro definition is ambiguous, complain.
550   if (M.isAmbiguous()) {
551     Diag(Identifier, diag::warn_pp_ambiguous_macro)
552       << Identifier.getIdentifierInfo();
553     Diag(MI->getDefinitionLoc(), diag::note_pp_ambiguous_macro_chosen)
554       << Identifier.getIdentifierInfo();
555     M.forAllDefinitions([&](const MacroInfo *OtherMI) {
556       if (OtherMI != MI)
557         Diag(OtherMI->getDefinitionLoc(), diag::note_pp_ambiguous_macro_other)
558           << Identifier.getIdentifierInfo();
559     });
560   }
561 
562   // If we started lexing a macro, enter the macro expansion body.
563 
564   // If this macro expands to no tokens, don't bother to push it onto the
565   // expansion stack, only to take it right back off.
566   if (MI->getNumTokens() == 0) {
567     // No need for arg info.
568     if (Args) Args->destroy(*this);
569 
570     // Propagate whitespace info as if we had pushed, then popped,
571     // a macro context.
572     Identifier.setFlag(Token::LeadingEmptyMacro);
573     PropagateLineStartLeadingSpaceInfo(Identifier);
574     ++NumFastMacroExpanded;
575     return false;
576   } else if (MI->getNumTokens() == 1 &&
577              isTrivialSingleTokenExpansion(MI, Identifier.getIdentifierInfo(),
578                                            *this)) {
579     // Otherwise, if this macro expands into a single trivially-expanded
580     // token: expand it now.  This handles common cases like
581     // "#define VAL 42".
582 
583     // No need for arg info.
584     if (Args) Args->destroy(*this);
585 
586     // Propagate the isAtStartOfLine/hasLeadingSpace markers of the macro
587     // identifier to the expanded token.
588     bool isAtStartOfLine = Identifier.isAtStartOfLine();
589     bool hasLeadingSpace = Identifier.hasLeadingSpace();
590 
591     // Replace the result token.
592     Identifier = MI->getReplacementToken(0);
593 
594     // Restore the StartOfLine/LeadingSpace markers.
595     Identifier.setFlagValue(Token::StartOfLine , isAtStartOfLine);
596     Identifier.setFlagValue(Token::LeadingSpace, hasLeadingSpace);
597 
598     // Update the tokens location to include both its expansion and physical
599     // locations.
600     SourceLocation Loc =
601       SourceMgr.createExpansionLoc(Identifier.getLocation(), ExpandLoc,
602                                    ExpansionEnd,Identifier.getLength());
603     Identifier.setLocation(Loc);
604 
605     // If this is a disabled macro or #define X X, we must mark the result as
606     // unexpandable.
607     if (IdentifierInfo *NewII = Identifier.getIdentifierInfo()) {
608       if (MacroInfo *NewMI = getMacroInfo(NewII))
609         if (!NewMI->isEnabled() || NewMI == MI) {
610           Identifier.setFlag(Token::DisableExpand);
611           // Don't warn for "#define X X" like "#define bool bool" from
612           // stdbool.h.
613           if (NewMI != MI || MI->isFunctionLike())
614             Diag(Identifier, diag::pp_disabled_macro_expansion);
615         }
616     }
617 
618     // Since this is not an identifier token, it can't be macro expanded, so
619     // we're done.
620     ++NumFastMacroExpanded;
621     return true;
622   }
623 
624   // Start expanding the macro.
625   EnterMacro(Identifier, ExpansionEnd, MI, Args);
626   return false;
627 }
628 
629 enum Bracket {
630   Brace,
631   Paren
632 };
633 
634 /// CheckMatchedBrackets - Returns true if the braces and parentheses in the
635 /// token vector are properly nested.
636 static bool CheckMatchedBrackets(const SmallVectorImpl<Token> &Tokens) {
637   SmallVector<Bracket, 8> Brackets;
638   for (SmallVectorImpl<Token>::const_iterator I = Tokens.begin(),
639                                               E = Tokens.end();
640        I != E; ++I) {
641     if (I->is(tok::l_paren)) {
642       Brackets.push_back(Paren);
643     } else if (I->is(tok::r_paren)) {
644       if (Brackets.empty() || Brackets.back() == Brace)
645         return false;
646       Brackets.pop_back();
647     } else if (I->is(tok::l_brace)) {
648       Brackets.push_back(Brace);
649     } else if (I->is(tok::r_brace)) {
650       if (Brackets.empty() || Brackets.back() == Paren)
651         return false;
652       Brackets.pop_back();
653     }
654   }
655   return Brackets.empty();
656 }
657 
658 /// GenerateNewArgTokens - Returns true if OldTokens can be converted to a new
659 /// vector of tokens in NewTokens.  The new number of arguments will be placed
660 /// in NumArgs and the ranges which need to surrounded in parentheses will be
661 /// in ParenHints.
662 /// Returns false if the token stream cannot be changed.  If this is because
663 /// of an initializer list starting a macro argument, the range of those
664 /// initializer lists will be place in InitLists.
665 static bool GenerateNewArgTokens(Preprocessor &PP,
666                                  SmallVectorImpl<Token> &OldTokens,
667                                  SmallVectorImpl<Token> &NewTokens,
668                                  unsigned &NumArgs,
669                                  SmallVectorImpl<SourceRange> &ParenHints,
670                                  SmallVectorImpl<SourceRange> &InitLists) {
671   if (!CheckMatchedBrackets(OldTokens))
672     return false;
673 
674   // Once it is known that the brackets are matched, only a simple count of the
675   // braces is needed.
676   unsigned Braces = 0;
677 
678   // First token of a new macro argument.
679   SmallVectorImpl<Token>::iterator ArgStartIterator = OldTokens.begin();
680 
681   // First closing brace in a new macro argument.  Used to generate
682   // SourceRanges for InitLists.
683   SmallVectorImpl<Token>::iterator ClosingBrace = OldTokens.end();
684   NumArgs = 0;
685   Token TempToken;
686   // Set to true when a macro separator token is found inside a braced list.
687   // If true, the fixed argument spans multiple old arguments and ParenHints
688   // will be updated.
689   bool FoundSeparatorToken = false;
690   for (SmallVectorImpl<Token>::iterator I = OldTokens.begin(),
691                                         E = OldTokens.end();
692        I != E; ++I) {
693     if (I->is(tok::l_brace)) {
694       ++Braces;
695     } else if (I->is(tok::r_brace)) {
696       --Braces;
697       if (Braces == 0 && ClosingBrace == E && FoundSeparatorToken)
698         ClosingBrace = I;
699     } else if (I->is(tok::eof)) {
700       // EOF token is used to separate macro arguments
701       if (Braces != 0) {
702         // Assume comma separator is actually braced list separator and change
703         // it back to a comma.
704         FoundSeparatorToken = true;
705         I->setKind(tok::comma);
706         I->setLength(1);
707       } else { // Braces == 0
708         // Separator token still separates arguments.
709         ++NumArgs;
710 
711         // If the argument starts with a brace, it can't be fixed with
712         // parentheses.  A different diagnostic will be given.
713         if (FoundSeparatorToken && ArgStartIterator->is(tok::l_brace)) {
714           InitLists.push_back(
715               SourceRange(ArgStartIterator->getLocation(),
716                           PP.getLocForEndOfToken(ClosingBrace->getLocation())));
717           ClosingBrace = E;
718         }
719 
720         // Add left paren
721         if (FoundSeparatorToken) {
722           TempToken.startToken();
723           TempToken.setKind(tok::l_paren);
724           TempToken.setLocation(ArgStartIterator->getLocation());
725           TempToken.setLength(0);
726           NewTokens.push_back(TempToken);
727         }
728 
729         // Copy over argument tokens
730         NewTokens.insert(NewTokens.end(), ArgStartIterator, I);
731 
732         // Add right paren and store the paren locations in ParenHints
733         if (FoundSeparatorToken) {
734           SourceLocation Loc = PP.getLocForEndOfToken((I - 1)->getLocation());
735           TempToken.startToken();
736           TempToken.setKind(tok::r_paren);
737           TempToken.setLocation(Loc);
738           TempToken.setLength(0);
739           NewTokens.push_back(TempToken);
740           ParenHints.push_back(SourceRange(ArgStartIterator->getLocation(),
741                                            Loc));
742         }
743 
744         // Copy separator token
745         NewTokens.push_back(*I);
746 
747         // Reset values
748         ArgStartIterator = I + 1;
749         FoundSeparatorToken = false;
750       }
751     }
752   }
753 
754   return !ParenHints.empty() && InitLists.empty();
755 }
756 
757 /// ReadFunctionLikeMacroArgs - After reading "MACRO" and knowing that the next
758 /// token is the '(' of the macro, this method is invoked to read all of the
759 /// actual arguments specified for the macro invocation.  This returns null on
760 /// error.
761 MacroArgs *Preprocessor::ReadMacroCallArgumentList(Token &MacroName,
762                                                    MacroInfo *MI,
763                                                    SourceLocation &MacroEnd) {
764   // The number of fixed arguments to parse.
765   unsigned NumFixedArgsLeft = MI->getNumParams();
766   bool isVariadic = MI->isVariadic();
767 
768   // Outer loop, while there are more arguments, keep reading them.
769   Token Tok;
770 
771   // Read arguments as unexpanded tokens.  This avoids issues, e.g., where
772   // an argument value in a macro could expand to ',' or '(' or ')'.
773   LexUnexpandedToken(Tok);
774   assert(Tok.is(tok::l_paren) && "Error computing l-paren-ness?");
775 
776   // ArgTokens - Build up a list of tokens that make up each argument.  Each
777   // argument is separated by an EOF token.  Use a SmallVector so we can avoid
778   // heap allocations in the common case.
779   SmallVector<Token, 64> ArgTokens;
780   bool ContainsCodeCompletionTok = false;
781   bool FoundElidedComma = false;
782 
783   SourceLocation TooManyArgsLoc;
784 
785   unsigned NumActuals = 0;
786   while (Tok.isNot(tok::r_paren)) {
787     if (ContainsCodeCompletionTok && Tok.isOneOf(tok::eof, tok::eod))
788       break;
789 
790     assert(Tok.isOneOf(tok::l_paren, tok::comma) &&
791            "only expect argument separators here");
792 
793     size_t ArgTokenStart = ArgTokens.size();
794     SourceLocation ArgStartLoc = Tok.getLocation();
795 
796     // C99 6.10.3p11: Keep track of the number of l_parens we have seen.  Note
797     // that we already consumed the first one.
798     unsigned NumParens = 0;
799 
800     while (true) {
801       // Read arguments as unexpanded tokens.  This avoids issues, e.g., where
802       // an argument value in a macro could expand to ',' or '(' or ')'.
803       LexUnexpandedToken(Tok);
804 
805       if (Tok.isOneOf(tok::eof, tok::eod)) { // "#if f(<eof>" & "#if f(\n"
806         if (!ContainsCodeCompletionTok) {
807           Diag(MacroName, diag::err_unterm_macro_invoc);
808           Diag(MI->getDefinitionLoc(), diag::note_macro_here)
809             << MacroName.getIdentifierInfo();
810           // Do not lose the EOF/EOD.  Return it to the client.
811           MacroName = Tok;
812           return nullptr;
813         }
814         // Do not lose the EOF/EOD.
815         auto Toks = std::make_unique<Token[]>(1);
816         Toks[0] = Tok;
817         EnterTokenStream(std::move(Toks), 1, true, /*IsReinject*/ false);
818         break;
819       } else if (Tok.is(tok::r_paren)) {
820         // If we found the ) token, the macro arg list is done.
821         if (NumParens-- == 0) {
822           MacroEnd = Tok.getLocation();
823           if (!ArgTokens.empty() &&
824               ArgTokens.back().commaAfterElided()) {
825             FoundElidedComma = true;
826           }
827           break;
828         }
829       } else if (Tok.is(tok::l_paren)) {
830         ++NumParens;
831       } else if (Tok.is(tok::comma)) {
832         // In Microsoft-compatibility mode, single commas from nested macro
833         // expansions should not be considered as argument separators. We test
834         // for this with the IgnoredComma token flag.
835         if (Tok.getFlags() & Token::IgnoredComma) {
836           // However, in MSVC's preprocessor, subsequent expansions do treat
837           // these commas as argument separators. This leads to a common
838           // workaround used in macros that need to work in both MSVC and
839           // compliant preprocessors. Therefore, the IgnoredComma flag can only
840           // apply once to any given token.
841           Tok.clearFlag(Token::IgnoredComma);
842         } else if (NumParens == 0) {
843           // Comma ends this argument if there are more fixed arguments
844           // expected. However, if this is a variadic macro, and this is part of
845           // the variadic part, then the comma is just an argument token.
846           if (!isVariadic)
847             break;
848           if (NumFixedArgsLeft > 1)
849             break;
850         }
851       } else if (Tok.is(tok::comment) && !KeepMacroComments) {
852         // If this is a comment token in the argument list and we're just in
853         // -C mode (not -CC mode), discard the comment.
854         continue;
855       } else if (!Tok.isAnnotation() && Tok.getIdentifierInfo() != nullptr) {
856         // Reading macro arguments can cause macros that we are currently
857         // expanding from to be popped off the expansion stack.  Doing so causes
858         // them to be reenabled for expansion.  Here we record whether any
859         // identifiers we lex as macro arguments correspond to disabled macros.
860         // If so, we mark the token as noexpand.  This is a subtle aspect of
861         // C99 6.10.3.4p2.
862         if (MacroInfo *MI = getMacroInfo(Tok.getIdentifierInfo()))
863           if (!MI->isEnabled())
864             Tok.setFlag(Token::DisableExpand);
865       } else if (Tok.is(tok::code_completion)) {
866         ContainsCodeCompletionTok = true;
867         if (CodeComplete)
868           CodeComplete->CodeCompleteMacroArgument(MacroName.getIdentifierInfo(),
869                                                   MI, NumActuals);
870         // Don't mark that we reached the code-completion point because the
871         // parser is going to handle the token and there will be another
872         // code-completion callback.
873       }
874 
875       ArgTokens.push_back(Tok);
876     }
877 
878     // If this was an empty argument list foo(), don't add this as an empty
879     // argument.
880     if (ArgTokens.empty() && Tok.getKind() == tok::r_paren)
881       break;
882 
883     // If this is not a variadic macro, and too many args were specified, emit
884     // an error.
885     if (!isVariadic && NumFixedArgsLeft == 0 && TooManyArgsLoc.isInvalid()) {
886       if (ArgTokens.size() != ArgTokenStart)
887         TooManyArgsLoc = ArgTokens[ArgTokenStart].getLocation();
888       else
889         TooManyArgsLoc = ArgStartLoc;
890     }
891 
892     // Empty arguments are standard in C99 and C++0x, and are supported as an
893     // extension in other modes.
894     if (ArgTokens.size() == ArgTokenStart && !getLangOpts().C99)
895       Diag(Tok, getLangOpts().CPlusPlus11
896                     ? diag::warn_cxx98_compat_empty_fnmacro_arg
897                     : diag::ext_empty_fnmacro_arg);
898 
899     // Add a marker EOF token to the end of the token list for this argument.
900     Token EOFTok;
901     EOFTok.startToken();
902     EOFTok.setKind(tok::eof);
903     EOFTok.setLocation(Tok.getLocation());
904     EOFTok.setLength(0);
905     ArgTokens.push_back(EOFTok);
906     ++NumActuals;
907     if (!ContainsCodeCompletionTok && NumFixedArgsLeft != 0)
908       --NumFixedArgsLeft;
909   }
910 
911   // Okay, we either found the r_paren.  Check to see if we parsed too few
912   // arguments.
913   unsigned MinArgsExpected = MI->getNumParams();
914 
915   // If this is not a variadic macro, and too many args were specified, emit
916   // an error.
917   if (!isVariadic && NumActuals > MinArgsExpected &&
918       !ContainsCodeCompletionTok) {
919     // Emit the diagnostic at the macro name in case there is a missing ).
920     // Emitting it at the , could be far away from the macro name.
921     Diag(TooManyArgsLoc, diag::err_too_many_args_in_macro_invoc);
922     Diag(MI->getDefinitionLoc(), diag::note_macro_here)
923       << MacroName.getIdentifierInfo();
924 
925     // Commas from braced initializer lists will be treated as argument
926     // separators inside macros.  Attempt to correct for this with parentheses.
927     // TODO: See if this can be generalized to angle brackets for templates
928     // inside macro arguments.
929 
930     SmallVector<Token, 4> FixedArgTokens;
931     unsigned FixedNumArgs = 0;
932     SmallVector<SourceRange, 4> ParenHints, InitLists;
933     if (!GenerateNewArgTokens(*this, ArgTokens, FixedArgTokens, FixedNumArgs,
934                               ParenHints, InitLists)) {
935       if (!InitLists.empty()) {
936         DiagnosticBuilder DB =
937             Diag(MacroName,
938                  diag::note_init_list_at_beginning_of_macro_argument);
939         for (SourceRange Range : InitLists)
940           DB << Range;
941       }
942       return nullptr;
943     }
944     if (FixedNumArgs != MinArgsExpected)
945       return nullptr;
946 
947     DiagnosticBuilder DB = Diag(MacroName, diag::note_suggest_parens_for_macro);
948     for (SourceRange ParenLocation : ParenHints) {
949       DB << FixItHint::CreateInsertion(ParenLocation.getBegin(), "(");
950       DB << FixItHint::CreateInsertion(ParenLocation.getEnd(), ")");
951     }
952     ArgTokens.swap(FixedArgTokens);
953     NumActuals = FixedNumArgs;
954   }
955 
956   // See MacroArgs instance var for description of this.
957   bool isVarargsElided = false;
958 
959   if (ContainsCodeCompletionTok) {
960     // Recover from not-fully-formed macro invocation during code-completion.
961     Token EOFTok;
962     EOFTok.startToken();
963     EOFTok.setKind(tok::eof);
964     EOFTok.setLocation(Tok.getLocation());
965     EOFTok.setLength(0);
966     for (; NumActuals < MinArgsExpected; ++NumActuals)
967       ArgTokens.push_back(EOFTok);
968   }
969 
970   if (NumActuals < MinArgsExpected) {
971     // There are several cases where too few arguments is ok, handle them now.
972     if (NumActuals == 0 && MinArgsExpected == 1) {
973       // #define A(X)  or  #define A(...)   ---> A()
974 
975       // If there is exactly one argument, and that argument is missing,
976       // then we have an empty "()" argument empty list.  This is fine, even if
977       // the macro expects one argument (the argument is just empty).
978       isVarargsElided = MI->isVariadic();
979     } else if ((FoundElidedComma || MI->isVariadic()) &&
980                (NumActuals+1 == MinArgsExpected ||  // A(x, ...) -> A(X)
981                 (NumActuals == 0 && MinArgsExpected == 2))) {// A(x,...) -> A()
982       // Varargs where the named vararg parameter is missing: OK as extension.
983       //   #define A(x, ...)
984       //   A("blah")
985       //
986       // If the macro contains the comma pasting extension, the diagnostic
987       // is suppressed; we know we'll get another diagnostic later.
988       if (!MI->hasCommaPasting()) {
989         Diag(Tok, diag::ext_missing_varargs_arg);
990         Diag(MI->getDefinitionLoc(), diag::note_macro_here)
991           << MacroName.getIdentifierInfo();
992       }
993 
994       // Remember this occurred, allowing us to elide the comma when used for
995       // cases like:
996       //   #define A(x, foo...) blah(a, ## foo)
997       //   #define B(x, ...) blah(a, ## __VA_ARGS__)
998       //   #define C(...) blah(a, ## __VA_ARGS__)
999       //  A(x) B(x) C()
1000       isVarargsElided = true;
1001     } else if (!ContainsCodeCompletionTok) {
1002       // Otherwise, emit the error.
1003       Diag(Tok, diag::err_too_few_args_in_macro_invoc);
1004       Diag(MI->getDefinitionLoc(), diag::note_macro_here)
1005         << MacroName.getIdentifierInfo();
1006       return nullptr;
1007     }
1008 
1009     // Add a marker EOF token to the end of the token list for this argument.
1010     SourceLocation EndLoc = Tok.getLocation();
1011     Tok.startToken();
1012     Tok.setKind(tok::eof);
1013     Tok.setLocation(EndLoc);
1014     Tok.setLength(0);
1015     ArgTokens.push_back(Tok);
1016 
1017     // If we expect two arguments, add both as empty.
1018     if (NumActuals == 0 && MinArgsExpected == 2)
1019       ArgTokens.push_back(Tok);
1020 
1021   } else if (NumActuals > MinArgsExpected && !MI->isVariadic() &&
1022              !ContainsCodeCompletionTok) {
1023     // Emit the diagnostic at the macro name in case there is a missing ).
1024     // Emitting it at the , could be far away from the macro name.
1025     Diag(MacroName, diag::err_too_many_args_in_macro_invoc);
1026     Diag(MI->getDefinitionLoc(), diag::note_macro_here)
1027       << MacroName.getIdentifierInfo();
1028     return nullptr;
1029   }
1030 
1031   return MacroArgs::create(MI, ArgTokens, isVarargsElided, *this);
1032 }
1033 
1034 /// Keeps macro expanded tokens for TokenLexers.
1035 //
1036 /// Works like a stack; a TokenLexer adds the macro expanded tokens that is
1037 /// going to lex in the cache and when it finishes the tokens are removed
1038 /// from the end of the cache.
1039 Token *Preprocessor::cacheMacroExpandedTokens(TokenLexer *tokLexer,
1040                                               ArrayRef<Token> tokens) {
1041   assert(tokLexer);
1042   if (tokens.empty())
1043     return nullptr;
1044 
1045   size_t newIndex = MacroExpandedTokens.size();
1046   bool cacheNeedsToGrow = tokens.size() >
1047                       MacroExpandedTokens.capacity()-MacroExpandedTokens.size();
1048   MacroExpandedTokens.append(tokens.begin(), tokens.end());
1049 
1050   if (cacheNeedsToGrow) {
1051     // Go through all the TokenLexers whose 'Tokens' pointer points in the
1052     // buffer and update the pointers to the (potential) new buffer array.
1053     for (const auto &Lexer : MacroExpandingLexersStack) {
1054       TokenLexer *prevLexer;
1055       size_t tokIndex;
1056       std::tie(prevLexer, tokIndex) = Lexer;
1057       prevLexer->Tokens = MacroExpandedTokens.data() + tokIndex;
1058     }
1059   }
1060 
1061   MacroExpandingLexersStack.push_back(std::make_pair(tokLexer, newIndex));
1062   return MacroExpandedTokens.data() + newIndex;
1063 }
1064 
1065 void Preprocessor::removeCachedMacroExpandedTokensOfLastLexer() {
1066   assert(!MacroExpandingLexersStack.empty());
1067   size_t tokIndex = MacroExpandingLexersStack.back().second;
1068   assert(tokIndex < MacroExpandedTokens.size());
1069   // Pop the cached macro expanded tokens from the end.
1070   MacroExpandedTokens.resize(tokIndex);
1071   MacroExpandingLexersStack.pop_back();
1072 }
1073 
1074 /// ComputeDATE_TIME - Compute the current time, enter it into the specified
1075 /// scratch buffer, then return DATELoc/TIMELoc locations with the position of
1076 /// the identifier tokens inserted.
1077 static void ComputeDATE_TIME(SourceLocation &DATELoc, SourceLocation &TIMELoc,
1078                              Preprocessor &PP) {
1079   time_t TT = time(nullptr);
1080   struct tm *TM = localtime(&TT);
1081 
1082   static const char * const Months[] = {
1083     "Jan","Feb","Mar","Apr","May","Jun","Jul","Aug","Sep","Oct","Nov","Dec"
1084   };
1085 
1086   {
1087     SmallString<32> TmpBuffer;
1088     llvm::raw_svector_ostream TmpStream(TmpBuffer);
1089     TmpStream << llvm::format("\"%s %2d %4d\"", Months[TM->tm_mon],
1090                               TM->tm_mday, TM->tm_year + 1900);
1091     Token TmpTok;
1092     TmpTok.startToken();
1093     PP.CreateString(TmpStream.str(), TmpTok);
1094     DATELoc = TmpTok.getLocation();
1095   }
1096 
1097   {
1098     SmallString<32> TmpBuffer;
1099     llvm::raw_svector_ostream TmpStream(TmpBuffer);
1100     TmpStream << llvm::format("\"%02d:%02d:%02d\"",
1101                               TM->tm_hour, TM->tm_min, TM->tm_sec);
1102     Token TmpTok;
1103     TmpTok.startToken();
1104     PP.CreateString(TmpStream.str(), TmpTok);
1105     TIMELoc = TmpTok.getLocation();
1106   }
1107 }
1108 
1109 /// HasFeature - Return true if we recognize and implement the feature
1110 /// specified by the identifier as a standard language feature.
1111 static bool HasFeature(const Preprocessor &PP, StringRef Feature) {
1112   const LangOptions &LangOpts = PP.getLangOpts();
1113 
1114   // Normalize the feature name, __foo__ becomes foo.
1115   if (Feature.startswith("__") && Feature.endswith("__") && Feature.size() >= 4)
1116     Feature = Feature.substr(2, Feature.size() - 4);
1117 
1118 #define FEATURE(Name, Predicate) .Case(#Name, Predicate)
1119   return llvm::StringSwitch<bool>(Feature)
1120 #include "clang/Basic/Features.def"
1121       .Default(false);
1122 #undef FEATURE
1123 }
1124 
1125 /// HasExtension - Return true if we recognize and implement the feature
1126 /// specified by the identifier, either as an extension or a standard language
1127 /// feature.
1128 static bool HasExtension(const Preprocessor &PP, StringRef Extension) {
1129   if (HasFeature(PP, Extension))
1130     return true;
1131 
1132   // If the use of an extension results in an error diagnostic, extensions are
1133   // effectively unavailable, so just return false here.
1134   if (PP.getDiagnostics().getExtensionHandlingBehavior() >=
1135       diag::Severity::Error)
1136     return false;
1137 
1138   const LangOptions &LangOpts = PP.getLangOpts();
1139 
1140   // Normalize the extension name, __foo__ becomes foo.
1141   if (Extension.startswith("__") && Extension.endswith("__") &&
1142       Extension.size() >= 4)
1143     Extension = Extension.substr(2, Extension.size() - 4);
1144 
1145     // Because we inherit the feature list from HasFeature, this string switch
1146     // must be less restrictive than HasFeature's.
1147 #define EXTENSION(Name, Predicate) .Case(#Name, Predicate)
1148   return llvm::StringSwitch<bool>(Extension)
1149 #include "clang/Basic/Features.def"
1150       .Default(false);
1151 #undef EXTENSION
1152 }
1153 
1154 /// EvaluateHasIncludeCommon - Process a '__has_include("path")'
1155 /// or '__has_include_next("path")' expression.
1156 /// Returns true if successful.
1157 static bool EvaluateHasIncludeCommon(Token &Tok,
1158                                      IdentifierInfo *II, Preprocessor &PP,
1159                                      const DirectoryLookup *LookupFrom,
1160                                      const FileEntry *LookupFromFile) {
1161   // Save the location of the current token.  If a '(' is later found, use
1162   // that location.  If not, use the end of this location instead.
1163   SourceLocation LParenLoc = Tok.getLocation();
1164 
1165   // These expressions are only allowed within a preprocessor directive.
1166   if (!PP.isParsingIfOrElifDirective()) {
1167     PP.Diag(LParenLoc, diag::err_pp_directive_required) << II;
1168     // Return a valid identifier token.
1169     assert(Tok.is(tok::identifier));
1170     Tok.setIdentifierInfo(II);
1171     return false;
1172   }
1173 
1174   // Get '('. If we don't have a '(', try to form a header-name token.
1175   do {
1176     if (PP.LexHeaderName(Tok))
1177       return false;
1178   } while (Tok.getKind() == tok::comment);
1179 
1180   // Ensure we have a '('.
1181   if (Tok.isNot(tok::l_paren)) {
1182     // No '(', use end of last token.
1183     LParenLoc = PP.getLocForEndOfToken(LParenLoc);
1184     PP.Diag(LParenLoc, diag::err_pp_expected_after) << II << tok::l_paren;
1185     // If the next token looks like a filename or the start of one,
1186     // assume it is and process it as such.
1187     if (Tok.isNot(tok::header_name))
1188       return false;
1189   } else {
1190     // Save '(' location for possible missing ')' message.
1191     LParenLoc = Tok.getLocation();
1192     if (PP.LexHeaderName(Tok))
1193       return false;
1194   }
1195 
1196   if (Tok.isNot(tok::header_name)) {
1197     PP.Diag(Tok.getLocation(), diag::err_pp_expects_filename);
1198     return false;
1199   }
1200 
1201   // Reserve a buffer to get the spelling.
1202   SmallString<128> FilenameBuffer;
1203   bool Invalid = false;
1204   StringRef Filename = PP.getSpelling(Tok, FilenameBuffer, &Invalid);
1205   if (Invalid)
1206     return false;
1207 
1208   SourceLocation FilenameLoc = Tok.getLocation();
1209 
1210   // Get ')'.
1211   PP.LexNonComment(Tok);
1212 
1213   // Ensure we have a trailing ).
1214   if (Tok.isNot(tok::r_paren)) {
1215     PP.Diag(PP.getLocForEndOfToken(FilenameLoc), diag::err_pp_expected_after)
1216         << II << tok::r_paren;
1217     PP.Diag(LParenLoc, diag::note_matching) << tok::l_paren;
1218     return false;
1219   }
1220 
1221   bool isAngled = PP.GetIncludeFilenameSpelling(Tok.getLocation(), Filename);
1222   // If GetIncludeFilenameSpelling set the start ptr to null, there was an
1223   // error.
1224   if (Filename.empty())
1225     return false;
1226 
1227   // Search include directories.
1228   const DirectoryLookup *CurDir;
1229   Optional<FileEntryRef> File =
1230       PP.LookupFile(FilenameLoc, Filename, isAngled, LookupFrom, LookupFromFile,
1231                     CurDir, nullptr, nullptr, nullptr, nullptr, nullptr);
1232 
1233   if (PPCallbacks *Callbacks = PP.getPPCallbacks()) {
1234     SrcMgr::CharacteristicKind FileType = SrcMgr::C_User;
1235     if (File)
1236       FileType =
1237           PP.getHeaderSearchInfo().getFileDirFlavor(&File->getFileEntry());
1238     Callbacks->HasInclude(FilenameLoc, Filename, isAngled, File, FileType);
1239   }
1240 
1241   // Get the result value.  A result of true means the file exists.
1242   return File.hasValue();
1243 }
1244 
1245 /// EvaluateHasInclude - Process a '__has_include("path")' expression.
1246 /// Returns true if successful.
1247 static bool EvaluateHasInclude(Token &Tok, IdentifierInfo *II,
1248                                Preprocessor &PP) {
1249   return EvaluateHasIncludeCommon(Tok, II, PP, nullptr, nullptr);
1250 }
1251 
1252 /// EvaluateHasIncludeNext - Process '__has_include_next("path")' expression.
1253 /// Returns true if successful.
1254 static bool EvaluateHasIncludeNext(Token &Tok,
1255                                    IdentifierInfo *II, Preprocessor &PP) {
1256   // __has_include_next is like __has_include, except that we start
1257   // searching after the current found directory.  If we can't do this,
1258   // issue a diagnostic.
1259   // FIXME: Factor out duplication with
1260   // Preprocessor::HandleIncludeNextDirective.
1261   const DirectoryLookup *Lookup = PP.GetCurDirLookup();
1262   const FileEntry *LookupFromFile = nullptr;
1263   if (PP.isInPrimaryFile() && PP.getLangOpts().IsHeaderFile) {
1264     // If the main file is a header, then it's either for PCH/AST generation,
1265     // or libclang opened it. Either way, handle it as a normal include below
1266     // and do not complain about __has_include_next.
1267   } else if (PP.isInPrimaryFile()) {
1268     Lookup = nullptr;
1269     PP.Diag(Tok, diag::pp_include_next_in_primary);
1270   } else if (PP.getCurrentLexerSubmodule()) {
1271     // Start looking up in the directory *after* the one in which the current
1272     // file would be found, if any.
1273     assert(PP.getCurrentLexer() && "#include_next directive in macro?");
1274     LookupFromFile = PP.getCurrentLexer()->getFileEntry();
1275     Lookup = nullptr;
1276   } else if (!Lookup) {
1277     PP.Diag(Tok, diag::pp_include_next_absolute_path);
1278   } else {
1279     // Start looking up in the next directory.
1280     ++Lookup;
1281   }
1282 
1283   return EvaluateHasIncludeCommon(Tok, II, PP, Lookup, LookupFromFile);
1284 }
1285 
1286 /// Process single-argument builtin feature-like macros that return
1287 /// integer values.
1288 static void EvaluateFeatureLikeBuiltinMacro(llvm::raw_svector_ostream& OS,
1289                                             Token &Tok, IdentifierInfo *II,
1290                                             Preprocessor &PP,
1291                                             llvm::function_ref<
1292                                               int(Token &Tok,
1293                                                   bool &HasLexedNextTok)> Op) {
1294   // Parse the initial '('.
1295   PP.LexUnexpandedToken(Tok);
1296   if (Tok.isNot(tok::l_paren)) {
1297     PP.Diag(Tok.getLocation(), diag::err_pp_expected_after) << II
1298                                                             << tok::l_paren;
1299 
1300     // Provide a dummy '0' value on output stream to elide further errors.
1301     if (!Tok.isOneOf(tok::eof, tok::eod)) {
1302       OS << 0;
1303       Tok.setKind(tok::numeric_constant);
1304     }
1305     return;
1306   }
1307 
1308   unsigned ParenDepth = 1;
1309   SourceLocation LParenLoc = Tok.getLocation();
1310   llvm::Optional<int> Result;
1311 
1312   Token ResultTok;
1313   bool SuppressDiagnostic = false;
1314   while (true) {
1315     // Parse next token.
1316     PP.LexUnexpandedToken(Tok);
1317 
1318 already_lexed:
1319     switch (Tok.getKind()) {
1320       case tok::eof:
1321       case tok::eod:
1322         // Don't provide even a dummy value if the eod or eof marker is
1323         // reached.  Simply provide a diagnostic.
1324         PP.Diag(Tok.getLocation(), diag::err_unterm_macro_invoc);
1325         return;
1326 
1327       case tok::comma:
1328         if (!SuppressDiagnostic) {
1329           PP.Diag(Tok.getLocation(), diag::err_too_many_args_in_macro_invoc);
1330           SuppressDiagnostic = true;
1331         }
1332         continue;
1333 
1334       case tok::l_paren:
1335         ++ParenDepth;
1336         if (Result.hasValue())
1337           break;
1338         if (!SuppressDiagnostic) {
1339           PP.Diag(Tok.getLocation(), diag::err_pp_nested_paren) << II;
1340           SuppressDiagnostic = true;
1341         }
1342         continue;
1343 
1344       case tok::r_paren:
1345         if (--ParenDepth > 0)
1346           continue;
1347 
1348         // The last ')' has been reached; return the value if one found or
1349         // a diagnostic and a dummy value.
1350         if (Result.hasValue()) {
1351           OS << Result.getValue();
1352           // For strict conformance to __has_cpp_attribute rules, use 'L'
1353           // suffix for dated literals.
1354           if (Result.getValue() > 1)
1355             OS << 'L';
1356         } else {
1357           OS << 0;
1358           if (!SuppressDiagnostic)
1359             PP.Diag(Tok.getLocation(), diag::err_too_few_args_in_macro_invoc);
1360         }
1361         Tok.setKind(tok::numeric_constant);
1362         return;
1363 
1364       default: {
1365         // Parse the macro argument, if one not found so far.
1366         if (Result.hasValue())
1367           break;
1368 
1369         bool HasLexedNextToken = false;
1370         Result = Op(Tok, HasLexedNextToken);
1371         ResultTok = Tok;
1372         if (HasLexedNextToken)
1373           goto already_lexed;
1374         continue;
1375       }
1376     }
1377 
1378     // Diagnose missing ')'.
1379     if (!SuppressDiagnostic) {
1380       if (auto Diag = PP.Diag(Tok.getLocation(), diag::err_pp_expected_after)) {
1381         if (IdentifierInfo *LastII = ResultTok.getIdentifierInfo())
1382           Diag << LastII;
1383         else
1384           Diag << ResultTok.getKind();
1385         Diag << tok::r_paren << ResultTok.getLocation();
1386       }
1387       PP.Diag(LParenLoc, diag::note_matching) << tok::l_paren;
1388       SuppressDiagnostic = true;
1389     }
1390   }
1391 }
1392 
1393 /// Helper function to return the IdentifierInfo structure of a Token
1394 /// or generate a diagnostic if none available.
1395 static IdentifierInfo *ExpectFeatureIdentifierInfo(Token &Tok,
1396                                                    Preprocessor &PP,
1397                                                    signed DiagID) {
1398   IdentifierInfo *II;
1399   if (!Tok.isAnnotation() && (II = Tok.getIdentifierInfo()))
1400     return II;
1401 
1402   PP.Diag(Tok.getLocation(), DiagID);
1403   return nullptr;
1404 }
1405 
1406 /// Implements the __is_target_arch builtin macro.
1407 static bool isTargetArch(const TargetInfo &TI, const IdentifierInfo *II) {
1408   std::string ArchName = II->getName().lower() + "--";
1409   llvm::Triple Arch(ArchName);
1410   const llvm::Triple &TT = TI.getTriple();
1411   if (TT.isThumb()) {
1412     // arm matches thumb or thumbv7. armv7 matches thumbv7.
1413     if ((Arch.getSubArch() == llvm::Triple::NoSubArch ||
1414          Arch.getSubArch() == TT.getSubArch()) &&
1415         ((TT.getArch() == llvm::Triple::thumb &&
1416           Arch.getArch() == llvm::Triple::arm) ||
1417          (TT.getArch() == llvm::Triple::thumbeb &&
1418           Arch.getArch() == llvm::Triple::armeb)))
1419       return true;
1420   }
1421   // Check the parsed arch when it has no sub arch to allow Clang to
1422   // match thumb to thumbv7 but to prohibit matching thumbv6 to thumbv7.
1423   return (Arch.getSubArch() == llvm::Triple::NoSubArch ||
1424           Arch.getSubArch() == TT.getSubArch()) &&
1425          Arch.getArch() == TT.getArch();
1426 }
1427 
1428 /// Implements the __is_target_vendor builtin macro.
1429 static bool isTargetVendor(const TargetInfo &TI, const IdentifierInfo *II) {
1430   StringRef VendorName = TI.getTriple().getVendorName();
1431   if (VendorName.empty())
1432     VendorName = "unknown";
1433   return VendorName.equals_insensitive(II->getName());
1434 }
1435 
1436 /// Implements the __is_target_os builtin macro.
1437 static bool isTargetOS(const TargetInfo &TI, const IdentifierInfo *II) {
1438   std::string OSName =
1439       (llvm::Twine("unknown-unknown-") + II->getName().lower()).str();
1440   llvm::Triple OS(OSName);
1441   if (OS.getOS() == llvm::Triple::Darwin) {
1442     // Darwin matches macos, ios, etc.
1443     return TI.getTriple().isOSDarwin();
1444   }
1445   return TI.getTriple().getOS() == OS.getOS();
1446 }
1447 
1448 /// Implements the __is_target_environment builtin macro.
1449 static bool isTargetEnvironment(const TargetInfo &TI,
1450                                 const IdentifierInfo *II) {
1451   std::string EnvName = (llvm::Twine("---") + II->getName().lower()).str();
1452   llvm::Triple Env(EnvName);
1453   return TI.getTriple().getEnvironment() == Env.getEnvironment();
1454 }
1455 
1456 /// ExpandBuiltinMacro - If an identifier token is read that is to be expanded
1457 /// as a builtin macro, handle it and return the next token as 'Tok'.
1458 void Preprocessor::ExpandBuiltinMacro(Token &Tok) {
1459   // Figure out which token this is.
1460   IdentifierInfo *II = Tok.getIdentifierInfo();
1461   assert(II && "Can't be a macro without id info!");
1462 
1463   // If this is an _Pragma or Microsoft __pragma directive, expand it,
1464   // invoke the pragma handler, then lex the token after it.
1465   if (II == Ident_Pragma)
1466     return Handle_Pragma(Tok);
1467   else if (II == Ident__pragma) // in non-MS mode this is null
1468     return HandleMicrosoft__pragma(Tok);
1469 
1470   ++NumBuiltinMacroExpanded;
1471 
1472   SmallString<128> TmpBuffer;
1473   llvm::raw_svector_ostream OS(TmpBuffer);
1474 
1475   // Set up the return result.
1476   Tok.setIdentifierInfo(nullptr);
1477   Tok.clearFlag(Token::NeedsCleaning);
1478   bool IsAtStartOfLine = Tok.isAtStartOfLine();
1479   bool HasLeadingSpace = Tok.hasLeadingSpace();
1480 
1481   if (II == Ident__LINE__) {
1482     // C99 6.10.8: "__LINE__: The presumed line number (within the current
1483     // source file) of the current source line (an integer constant)".  This can
1484     // be affected by #line.
1485     SourceLocation Loc = Tok.getLocation();
1486 
1487     // Advance to the location of the first _, this might not be the first byte
1488     // of the token if it starts with an escaped newline.
1489     Loc = AdvanceToTokenCharacter(Loc, 0);
1490 
1491     // One wrinkle here is that GCC expands __LINE__ to location of the *end* of
1492     // a macro expansion.  This doesn't matter for object-like macros, but
1493     // can matter for a function-like macro that expands to contain __LINE__.
1494     // Skip down through expansion points until we find a file loc for the
1495     // end of the expansion history.
1496     Loc = SourceMgr.getExpansionRange(Loc).getEnd();
1497     PresumedLoc PLoc = SourceMgr.getPresumedLoc(Loc);
1498 
1499     // __LINE__ expands to a simple numeric value.
1500     OS << (PLoc.isValid()? PLoc.getLine() : 1);
1501     Tok.setKind(tok::numeric_constant);
1502   } else if (II == Ident__FILE__ || II == Ident__BASE_FILE__ ||
1503              II == Ident__FILE_NAME__) {
1504     // C99 6.10.8: "__FILE__: The presumed name of the current source file (a
1505     // character string literal)". This can be affected by #line.
1506     PresumedLoc PLoc = SourceMgr.getPresumedLoc(Tok.getLocation());
1507 
1508     // __BASE_FILE__ is a GNU extension that returns the top of the presumed
1509     // #include stack instead of the current file.
1510     if (II == Ident__BASE_FILE__ && PLoc.isValid()) {
1511       SourceLocation NextLoc = PLoc.getIncludeLoc();
1512       while (NextLoc.isValid()) {
1513         PLoc = SourceMgr.getPresumedLoc(NextLoc);
1514         if (PLoc.isInvalid())
1515           break;
1516 
1517         NextLoc = PLoc.getIncludeLoc();
1518       }
1519     }
1520 
1521     // Escape this filename.  Turn '\' -> '\\' '"' -> '\"'
1522     SmallString<256> FN;
1523     if (PLoc.isValid()) {
1524       // __FILE_NAME__ is a Clang-specific extension that expands to the
1525       // the last part of __FILE__.
1526       if (II == Ident__FILE_NAME__) {
1527         // Try to get the last path component, failing that return the original
1528         // presumed location.
1529         StringRef PLFileName = llvm::sys::path::filename(PLoc.getFilename());
1530         if (PLFileName != "")
1531           FN += PLFileName;
1532         else
1533           FN += PLoc.getFilename();
1534       } else {
1535         FN += PLoc.getFilename();
1536       }
1537       getLangOpts().remapPathPrefix(FN);
1538       Lexer::Stringify(FN);
1539       OS << '"' << FN << '"';
1540     }
1541     Tok.setKind(tok::string_literal);
1542   } else if (II == Ident__DATE__) {
1543     Diag(Tok.getLocation(), diag::warn_pp_date_time);
1544     if (!DATELoc.isValid())
1545       ComputeDATE_TIME(DATELoc, TIMELoc, *this);
1546     Tok.setKind(tok::string_literal);
1547     Tok.setLength(strlen("\"Mmm dd yyyy\""));
1548     Tok.setLocation(SourceMgr.createExpansionLoc(DATELoc, Tok.getLocation(),
1549                                                  Tok.getLocation(),
1550                                                  Tok.getLength()));
1551     return;
1552   } else if (II == Ident__TIME__) {
1553     Diag(Tok.getLocation(), diag::warn_pp_date_time);
1554     if (!TIMELoc.isValid())
1555       ComputeDATE_TIME(DATELoc, TIMELoc, *this);
1556     Tok.setKind(tok::string_literal);
1557     Tok.setLength(strlen("\"hh:mm:ss\""));
1558     Tok.setLocation(SourceMgr.createExpansionLoc(TIMELoc, Tok.getLocation(),
1559                                                  Tok.getLocation(),
1560                                                  Tok.getLength()));
1561     return;
1562   } else if (II == Ident__INCLUDE_LEVEL__) {
1563     // Compute the presumed include depth of this token.  This can be affected
1564     // by GNU line markers.
1565     unsigned Depth = 0;
1566 
1567     PresumedLoc PLoc = SourceMgr.getPresumedLoc(Tok.getLocation());
1568     if (PLoc.isValid()) {
1569       PLoc = SourceMgr.getPresumedLoc(PLoc.getIncludeLoc());
1570       for (; PLoc.isValid(); ++Depth)
1571         PLoc = SourceMgr.getPresumedLoc(PLoc.getIncludeLoc());
1572     }
1573 
1574     // __INCLUDE_LEVEL__ expands to a simple numeric value.
1575     OS << Depth;
1576     Tok.setKind(tok::numeric_constant);
1577   } else if (II == Ident__TIMESTAMP__) {
1578     Diag(Tok.getLocation(), diag::warn_pp_date_time);
1579     // MSVC, ICC, GCC, VisualAge C++ extension.  The generated string should be
1580     // of the form "Ddd Mmm dd hh::mm::ss yyyy", which is returned by asctime.
1581 
1582     // Get the file that we are lexing out of.  If we're currently lexing from
1583     // a macro, dig into the include stack.
1584     const FileEntry *CurFile = nullptr;
1585     PreprocessorLexer *TheLexer = getCurrentFileLexer();
1586 
1587     if (TheLexer)
1588       CurFile = SourceMgr.getFileEntryForID(TheLexer->getFileID());
1589 
1590     const char *Result;
1591     if (CurFile) {
1592       time_t TT = CurFile->getModificationTime();
1593       struct tm *TM = localtime(&TT);
1594       Result = asctime(TM);
1595     } else {
1596       Result = "??? ??? ?? ??:??:?? ????\n";
1597     }
1598     // Surround the string with " and strip the trailing newline.
1599     OS << '"' << StringRef(Result).drop_back() << '"';
1600     Tok.setKind(tok::string_literal);
1601   } else if (II == Ident__COUNTER__) {
1602     // __COUNTER__ expands to a simple numeric value.
1603     OS << CounterValue++;
1604     Tok.setKind(tok::numeric_constant);
1605   } else if (II == Ident__has_feature) {
1606     EvaluateFeatureLikeBuiltinMacro(OS, Tok, II, *this,
1607       [this](Token &Tok, bool &HasLexedNextToken) -> int {
1608         IdentifierInfo *II = ExpectFeatureIdentifierInfo(Tok, *this,
1609                                            diag::err_feature_check_malformed);
1610         return II && HasFeature(*this, II->getName());
1611       });
1612   } else if (II == Ident__has_extension) {
1613     EvaluateFeatureLikeBuiltinMacro(OS, Tok, II, *this,
1614       [this](Token &Tok, bool &HasLexedNextToken) -> int {
1615         IdentifierInfo *II = ExpectFeatureIdentifierInfo(Tok, *this,
1616                                            diag::err_feature_check_malformed);
1617         return II && HasExtension(*this, II->getName());
1618       });
1619   } else if (II == Ident__has_builtin) {
1620     EvaluateFeatureLikeBuiltinMacro(OS, Tok, II, *this,
1621       [this](Token &Tok, bool &HasLexedNextToken) -> int {
1622         IdentifierInfo *II = ExpectFeatureIdentifierInfo(Tok, *this,
1623                                            diag::err_feature_check_malformed);
1624         if (!II)
1625           return false;
1626         else if (II->getBuiltinID() != 0) {
1627           switch (II->getBuiltinID()) {
1628           case Builtin::BI__builtin_operator_new:
1629           case Builtin::BI__builtin_operator_delete:
1630             // denotes date of behavior change to support calling arbitrary
1631             // usual allocation and deallocation functions. Required by libc++
1632             return 201802;
1633           default:
1634             return true;
1635           }
1636           return true;
1637         } else if (II->getTokenID() != tok::identifier ||
1638                    II->hasRevertedTokenIDToIdentifier()) {
1639           // Treat all keywords that introduce a custom syntax of the form
1640           //
1641           //   '__some_keyword' '(' [...] ')'
1642           //
1643           // as being "builtin functions", even if the syntax isn't a valid
1644           // function call (for example, because the builtin takes a type
1645           // argument).
1646           if (II->getName().startswith("__builtin_") ||
1647               II->getName().startswith("__is_") ||
1648               II->getName().startswith("__has_"))
1649             return true;
1650           return llvm::StringSwitch<bool>(II->getName())
1651               .Case("__array_rank", true)
1652               .Case("__array_extent", true)
1653               .Case("__reference_binds_to_temporary", true)
1654               .Case("__underlying_type", true)
1655               .Default(false);
1656         } else {
1657           return llvm::StringSwitch<bool>(II->getName())
1658               // Report builtin templates as being builtins.
1659               .Case("__make_integer_seq", getLangOpts().CPlusPlus)
1660               .Case("__type_pack_element", getLangOpts().CPlusPlus)
1661               // Likewise for some builtin preprocessor macros.
1662               // FIXME: This is inconsistent; we usually suggest detecting
1663               // builtin macros via #ifdef. Don't add more cases here.
1664               .Case("__is_target_arch", true)
1665               .Case("__is_target_vendor", true)
1666               .Case("__is_target_os", true)
1667               .Case("__is_target_environment", true)
1668               .Default(false);
1669         }
1670       });
1671   } else if (II == Ident__is_identifier) {
1672     EvaluateFeatureLikeBuiltinMacro(OS, Tok, II, *this,
1673       [](Token &Tok, bool &HasLexedNextToken) -> int {
1674         return Tok.is(tok::identifier);
1675       });
1676   } else if (II == Ident__has_attribute) {
1677     EvaluateFeatureLikeBuiltinMacro(OS, Tok, II, *this,
1678       [this](Token &Tok, bool &HasLexedNextToken) -> int {
1679         IdentifierInfo *II = ExpectFeatureIdentifierInfo(Tok, *this,
1680                                            diag::err_feature_check_malformed);
1681         return II ? hasAttribute(AttrSyntax::GNU, nullptr, II,
1682                                  getTargetInfo(), getLangOpts()) : 0;
1683       });
1684   } else if (II == Ident__has_declspec) {
1685     EvaluateFeatureLikeBuiltinMacro(OS, Tok, II, *this,
1686       [this](Token &Tok, bool &HasLexedNextToken) -> int {
1687         IdentifierInfo *II = ExpectFeatureIdentifierInfo(Tok, *this,
1688                                            diag::err_feature_check_malformed);
1689         if (II) {
1690           const LangOptions &LangOpts = getLangOpts();
1691           return LangOpts.DeclSpecKeyword &&
1692                  hasAttribute(AttrSyntax::Declspec, nullptr, II,
1693                               getTargetInfo(), LangOpts);
1694         }
1695 
1696         return false;
1697       });
1698   } else if (II == Ident__has_cpp_attribute ||
1699              II == Ident__has_c_attribute) {
1700     bool IsCXX = II == Ident__has_cpp_attribute;
1701     EvaluateFeatureLikeBuiltinMacro(
1702         OS, Tok, II, *this, [&](Token &Tok, bool &HasLexedNextToken) -> int {
1703           IdentifierInfo *ScopeII = nullptr;
1704           IdentifierInfo *II = ExpectFeatureIdentifierInfo(
1705               Tok, *this, diag::err_feature_check_malformed);
1706           if (!II)
1707             return false;
1708 
1709           // It is possible to receive a scope token.  Read the "::", if it is
1710           // available, and the subsequent identifier.
1711           LexUnexpandedToken(Tok);
1712           if (Tok.isNot(tok::coloncolon))
1713             HasLexedNextToken = true;
1714           else {
1715             ScopeII = II;
1716             LexUnexpandedToken(Tok);
1717             II = ExpectFeatureIdentifierInfo(Tok, *this,
1718                                              diag::err_feature_check_malformed);
1719           }
1720 
1721           AttrSyntax Syntax = IsCXX ? AttrSyntax::CXX : AttrSyntax::C;
1722           return II ? hasAttribute(Syntax, ScopeII, II, getTargetInfo(),
1723                                    getLangOpts())
1724                     : 0;
1725         });
1726   } else if (II == Ident__has_include ||
1727              II == Ident__has_include_next) {
1728     // The argument to these two builtins should be a parenthesized
1729     // file name string literal using angle brackets (<>) or
1730     // double-quotes ("").
1731     bool Value;
1732     if (II == Ident__has_include)
1733       Value = EvaluateHasInclude(Tok, II, *this);
1734     else
1735       Value = EvaluateHasIncludeNext(Tok, II, *this);
1736 
1737     if (Tok.isNot(tok::r_paren))
1738       return;
1739     OS << (int)Value;
1740     Tok.setKind(tok::numeric_constant);
1741   } else if (II == Ident__has_warning) {
1742     // The argument should be a parenthesized string literal.
1743     EvaluateFeatureLikeBuiltinMacro(OS, Tok, II, *this,
1744       [this](Token &Tok, bool &HasLexedNextToken) -> int {
1745         std::string WarningName;
1746         SourceLocation StrStartLoc = Tok.getLocation();
1747 
1748         HasLexedNextToken = Tok.is(tok::string_literal);
1749         if (!FinishLexStringLiteral(Tok, WarningName, "'__has_warning'",
1750                                     /*AllowMacroExpansion=*/false))
1751           return false;
1752 
1753         // FIXME: Should we accept "-R..." flags here, or should that be
1754         // handled by a separate __has_remark?
1755         if (WarningName.size() < 3 || WarningName[0] != '-' ||
1756             WarningName[1] != 'W') {
1757           Diag(StrStartLoc, diag::warn_has_warning_invalid_option);
1758           return false;
1759         }
1760 
1761         // Finally, check if the warning flags maps to a diagnostic group.
1762         // We construct a SmallVector here to talk to getDiagnosticIDs().
1763         // Although we don't use the result, this isn't a hot path, and not
1764         // worth special casing.
1765         SmallVector<diag::kind, 10> Diags;
1766         return !getDiagnostics().getDiagnosticIDs()->
1767                 getDiagnosticsInGroup(diag::Flavor::WarningOrError,
1768                                       WarningName.substr(2), Diags);
1769       });
1770   } else if (II == Ident__building_module) {
1771     // The argument to this builtin should be an identifier. The
1772     // builtin evaluates to 1 when that identifier names the module we are
1773     // currently building.
1774     EvaluateFeatureLikeBuiltinMacro(OS, Tok, II, *this,
1775       [this](Token &Tok, bool &HasLexedNextToken) -> int {
1776         IdentifierInfo *II = ExpectFeatureIdentifierInfo(Tok, *this,
1777                                        diag::err_expected_id_building_module);
1778         return getLangOpts().isCompilingModule() && II &&
1779                (II->getName() == getLangOpts().CurrentModule);
1780       });
1781   } else if (II == Ident__MODULE__) {
1782     // The current module as an identifier.
1783     OS << getLangOpts().CurrentModule;
1784     IdentifierInfo *ModuleII = getIdentifierInfo(getLangOpts().CurrentModule);
1785     Tok.setIdentifierInfo(ModuleII);
1786     Tok.setKind(ModuleII->getTokenID());
1787   } else if (II == Ident__identifier) {
1788     SourceLocation Loc = Tok.getLocation();
1789 
1790     // We're expecting '__identifier' '(' identifier ')'. Try to recover
1791     // if the parens are missing.
1792     LexNonComment(Tok);
1793     if (Tok.isNot(tok::l_paren)) {
1794       // No '(', use end of last token.
1795       Diag(getLocForEndOfToken(Loc), diag::err_pp_expected_after)
1796         << II << tok::l_paren;
1797       // If the next token isn't valid as our argument, we can't recover.
1798       if (!Tok.isAnnotation() && Tok.getIdentifierInfo())
1799         Tok.setKind(tok::identifier);
1800       return;
1801     }
1802 
1803     SourceLocation LParenLoc = Tok.getLocation();
1804     LexNonComment(Tok);
1805 
1806     if (!Tok.isAnnotation() && Tok.getIdentifierInfo())
1807       Tok.setKind(tok::identifier);
1808     else if (Tok.is(tok::string_literal) && !Tok.hasUDSuffix()) {
1809       StringLiteralParser Literal(Tok, *this);
1810       if (Literal.hadError)
1811         return;
1812 
1813       Tok.setIdentifierInfo(getIdentifierInfo(Literal.GetString()));
1814       Tok.setKind(tok::identifier);
1815     } else {
1816       Diag(Tok.getLocation(), diag::err_pp_identifier_arg_not_identifier)
1817         << Tok.getKind();
1818       // Don't walk past anything that's not a real token.
1819       if (Tok.isOneOf(tok::eof, tok::eod) || Tok.isAnnotation())
1820         return;
1821     }
1822 
1823     // Discard the ')', preserving 'Tok' as our result.
1824     Token RParen;
1825     LexNonComment(RParen);
1826     if (RParen.isNot(tok::r_paren)) {
1827       Diag(getLocForEndOfToken(Tok.getLocation()), diag::err_pp_expected_after)
1828         << Tok.getKind() << tok::r_paren;
1829       Diag(LParenLoc, diag::note_matching) << tok::l_paren;
1830     }
1831     return;
1832   } else if (II == Ident__is_target_arch) {
1833     EvaluateFeatureLikeBuiltinMacro(
1834         OS, Tok, II, *this, [this](Token &Tok, bool &HasLexedNextToken) -> int {
1835           IdentifierInfo *II = ExpectFeatureIdentifierInfo(
1836               Tok, *this, diag::err_feature_check_malformed);
1837           return II && isTargetArch(getTargetInfo(), II);
1838         });
1839   } else if (II == Ident__is_target_vendor) {
1840     EvaluateFeatureLikeBuiltinMacro(
1841         OS, Tok, II, *this, [this](Token &Tok, bool &HasLexedNextToken) -> int {
1842           IdentifierInfo *II = ExpectFeatureIdentifierInfo(
1843               Tok, *this, diag::err_feature_check_malformed);
1844           return II && isTargetVendor(getTargetInfo(), II);
1845         });
1846   } else if (II == Ident__is_target_os) {
1847     EvaluateFeatureLikeBuiltinMacro(
1848         OS, Tok, II, *this, [this](Token &Tok, bool &HasLexedNextToken) -> int {
1849           IdentifierInfo *II = ExpectFeatureIdentifierInfo(
1850               Tok, *this, diag::err_feature_check_malformed);
1851           return II && isTargetOS(getTargetInfo(), II);
1852         });
1853   } else if (II == Ident__is_target_environment) {
1854     EvaluateFeatureLikeBuiltinMacro(
1855         OS, Tok, II, *this, [this](Token &Tok, bool &HasLexedNextToken) -> int {
1856           IdentifierInfo *II = ExpectFeatureIdentifierInfo(
1857               Tok, *this, diag::err_feature_check_malformed);
1858           return II && isTargetEnvironment(getTargetInfo(), II);
1859         });
1860   } else {
1861     llvm_unreachable("Unknown identifier!");
1862   }
1863   CreateString(OS.str(), Tok, Tok.getLocation(), Tok.getLocation());
1864   Tok.setFlagValue(Token::StartOfLine, IsAtStartOfLine);
1865   Tok.setFlagValue(Token::LeadingSpace, HasLeadingSpace);
1866 }
1867 
1868 void Preprocessor::markMacroAsUsed(MacroInfo *MI) {
1869   // If the 'used' status changed, and the macro requires 'unused' warning,
1870   // remove its SourceLocation from the warn-for-unused-macro locations.
1871   if (MI->isWarnIfUnused() && !MI->isUsed())
1872     WarnUnusedMacroLocs.erase(MI->getDefinitionLoc());
1873   MI->setIsUsed(true);
1874 }
1875