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      1 //===--- MacroExpansion.cpp - Top level Macro Expansion -------------------===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 //
     10 // This file implements the top level handling of macro expasion for the
     11 // preprocessor.
     12 //
     13 //===----------------------------------------------------------------------===//
     14 
     15 #include "clang/Lex/Preprocessor.h"
     16 #include "clang/Lex/MacroArgs.h"
     17 #include "clang/Basic/FileManager.h"
     18 #include "clang/Basic/SourceManager.h"
     19 #include "clang/Basic/TargetInfo.h"
     20 #include "clang/Lex/CodeCompletionHandler.h"
     21 #include "clang/Lex/ExternalPreprocessorSource.h"
     22 #include "clang/Lex/LexDiagnostic.h"
     23 #include "clang/Lex/MacroInfo.h"
     24 #include "llvm/ADT/STLExtras.h"
     25 #include "llvm/ADT/SmallString.h"
     26 #include "llvm/ADT/StringSwitch.h"
     27 #include "llvm/Config/llvm-config.h"
     28 #include "llvm/Support/ErrorHandling.h"
     29 #include "llvm/Support/Format.h"
     30 #include "llvm/Support/raw_ostream.h"
     31 #include <cstdio>
     32 #include <ctime>
     33 using namespace clang;
     34 
     35 MacroDirective *
     36 Preprocessor::getMacroDirectiveHistory(const IdentifierInfo *II) const {
     37   assert(II->hadMacroDefinition() && "Identifier has not been not a macro!");
     38 
     39   macro_iterator Pos = Macros.find(II);
     40   assert(Pos != Macros.end() && "Identifier macro info is missing!");
     41   return Pos->second;
     42 }
     43 
     44 void Preprocessor::appendMacroDirective(IdentifierInfo *II, MacroDirective *MD){
     45   assert(MD && "MacroDirective should be non-zero!");
     46   assert(!MD->getPrevious() && "Already attached to a MacroDirective history.");
     47 
     48   MacroDirective *&StoredMD = Macros[II];
     49   MD->setPrevious(StoredMD);
     50   StoredMD = MD;
     51   II->setHasMacroDefinition(MD->isDefined());
     52   bool isImportedMacro = isa<DefMacroDirective>(MD) &&
     53                          cast<DefMacroDirective>(MD)->isImported();
     54   if (II->isFromAST() && !isImportedMacro)
     55     II->setChangedSinceDeserialization();
     56 }
     57 
     58 void Preprocessor::setLoadedMacroDirective(IdentifierInfo *II,
     59                                            MacroDirective *MD) {
     60   assert(II && MD);
     61   MacroDirective *&StoredMD = Macros[II];
     62   assert(!StoredMD &&
     63          "the macro history was modified before initializing it from a pch");
     64   StoredMD = MD;
     65   // Setup the identifier as having associated macro history.
     66   II->setHasMacroDefinition(true);
     67   if (!MD->isDefined())
     68     II->setHasMacroDefinition(false);
     69 }
     70 
     71 /// RegisterBuiltinMacro - Register the specified identifier in the identifier
     72 /// table and mark it as a builtin macro to be expanded.
     73 static IdentifierInfo *RegisterBuiltinMacro(Preprocessor &PP, const char *Name){
     74   // Get the identifier.
     75   IdentifierInfo *Id = PP.getIdentifierInfo(Name);
     76 
     77   // Mark it as being a macro that is builtin.
     78   MacroInfo *MI = PP.AllocateMacroInfo(SourceLocation());
     79   MI->setIsBuiltinMacro();
     80   PP.appendDefMacroDirective(Id, MI);
     81   return Id;
     82 }
     83 
     84 
     85 /// RegisterBuiltinMacros - Register builtin macros, such as __LINE__ with the
     86 /// identifier table.
     87 void Preprocessor::RegisterBuiltinMacros() {
     88   Ident__LINE__ = RegisterBuiltinMacro(*this, "__LINE__");
     89   Ident__FILE__ = RegisterBuiltinMacro(*this, "__FILE__");
     90   Ident__DATE__ = RegisterBuiltinMacro(*this, "__DATE__");
     91   Ident__TIME__ = RegisterBuiltinMacro(*this, "__TIME__");
     92   Ident__COUNTER__ = RegisterBuiltinMacro(*this, "__COUNTER__");
     93   Ident_Pragma  = RegisterBuiltinMacro(*this, "_Pragma");
     94 
     95   // GCC Extensions.
     96   Ident__BASE_FILE__     = RegisterBuiltinMacro(*this, "__BASE_FILE__");
     97   Ident__INCLUDE_LEVEL__ = RegisterBuiltinMacro(*this, "__INCLUDE_LEVEL__");
     98   Ident__TIMESTAMP__     = RegisterBuiltinMacro(*this, "__TIMESTAMP__");
     99 
    100   // Clang Extensions.
    101   Ident__has_feature      = RegisterBuiltinMacro(*this, "__has_feature");
    102   Ident__has_extension    = RegisterBuiltinMacro(*this, "__has_extension");
    103   Ident__has_builtin      = RegisterBuiltinMacro(*this, "__has_builtin");
    104   Ident__has_attribute    = RegisterBuiltinMacro(*this, "__has_attribute");
    105   Ident__has_include      = RegisterBuiltinMacro(*this, "__has_include");
    106   Ident__has_include_next = RegisterBuiltinMacro(*this, "__has_include_next");
    107   Ident__has_warning      = RegisterBuiltinMacro(*this, "__has_warning");
    108 
    109   // Modules.
    110   if (LangOpts.Modules) {
    111     Ident__building_module  = RegisterBuiltinMacro(*this, "__building_module");
    112 
    113     // __MODULE__
    114     if (!LangOpts.CurrentModule.empty())
    115       Ident__MODULE__ = RegisterBuiltinMacro(*this, "__MODULE__");
    116     else
    117       Ident__MODULE__ = 0;
    118   } else {
    119     Ident__building_module = 0;
    120     Ident__MODULE__ = 0;
    121   }
    122 
    123   // Microsoft Extensions.
    124   if (LangOpts.MicrosoftExt)
    125     Ident__pragma = RegisterBuiltinMacro(*this, "__pragma");
    126   else
    127     Ident__pragma = 0;
    128 }
    129 
    130 /// isTrivialSingleTokenExpansion - Return true if MI, which has a single token
    131 /// in its expansion, currently expands to that token literally.
    132 static bool isTrivialSingleTokenExpansion(const MacroInfo *MI,
    133                                           const IdentifierInfo *MacroIdent,
    134                                           Preprocessor &PP) {
    135   IdentifierInfo *II = MI->getReplacementToken(0).getIdentifierInfo();
    136 
    137   // If the token isn't an identifier, it's always literally expanded.
    138   if (II == 0) return true;
    139 
    140   // If the information about this identifier is out of date, update it from
    141   // the external source.
    142   if (II->isOutOfDate())
    143     PP.getExternalSource()->updateOutOfDateIdentifier(*II);
    144 
    145   // If the identifier is a macro, and if that macro is enabled, it may be
    146   // expanded so it's not a trivial expansion.
    147   if (II->hasMacroDefinition() && PP.getMacroInfo(II)->isEnabled() &&
    148       // Fast expanding "#define X X" is ok, because X would be disabled.
    149       II != MacroIdent)
    150     return false;
    151 
    152   // If this is an object-like macro invocation, it is safe to trivially expand
    153   // it.
    154   if (MI->isObjectLike()) return true;
    155 
    156   // If this is a function-like macro invocation, it's safe to trivially expand
    157   // as long as the identifier is not a macro argument.
    158   for (MacroInfo::arg_iterator I = MI->arg_begin(), E = MI->arg_end();
    159        I != E; ++I)
    160     if (*I == II)
    161       return false;   // Identifier is a macro argument.
    162 
    163   return true;
    164 }
    165 
    166 
    167 /// isNextPPTokenLParen - Determine whether the next preprocessor token to be
    168 /// lexed is a '('.  If so, consume the token and return true, if not, this
    169 /// method should have no observable side-effect on the lexed tokens.
    170 bool Preprocessor::isNextPPTokenLParen() {
    171   // Do some quick tests for rejection cases.
    172   unsigned Val;
    173   if (CurLexer)
    174     Val = CurLexer->isNextPPTokenLParen();
    175   else if (CurPTHLexer)
    176     Val = CurPTHLexer->isNextPPTokenLParen();
    177   else
    178     Val = CurTokenLexer->isNextTokenLParen();
    179 
    180   if (Val == 2) {
    181     // We have run off the end.  If it's a source file we don't
    182     // examine enclosing ones (C99 5.1.1.2p4).  Otherwise walk up the
    183     // macro stack.
    184     if (CurPPLexer)
    185       return false;
    186     for (unsigned i = IncludeMacroStack.size(); i != 0; --i) {
    187       IncludeStackInfo &Entry = IncludeMacroStack[i-1];
    188       if (Entry.TheLexer)
    189         Val = Entry.TheLexer->isNextPPTokenLParen();
    190       else if (Entry.ThePTHLexer)
    191         Val = Entry.ThePTHLexer->isNextPPTokenLParen();
    192       else
    193         Val = Entry.TheTokenLexer->isNextTokenLParen();
    194 
    195       if (Val != 2)
    196         break;
    197 
    198       // Ran off the end of a source file?
    199       if (Entry.ThePPLexer)
    200         return false;
    201     }
    202   }
    203 
    204   // Okay, if we know that the token is a '(', lex it and return.  Otherwise we
    205   // have found something that isn't a '(' or we found the end of the
    206   // translation unit.  In either case, return false.
    207   return Val == 1;
    208 }
    209 
    210 /// HandleMacroExpandedIdentifier - If an identifier token is read that is to be
    211 /// expanded as a macro, handle it and return the next token as 'Identifier'.
    212 bool Preprocessor::HandleMacroExpandedIdentifier(Token &Identifier,
    213                                                  MacroDirective *MD) {
    214   MacroDirective::DefInfo Def = MD->getDefinition();
    215   assert(Def.isValid());
    216   MacroInfo *MI = Def.getMacroInfo();
    217 
    218   // If this is a macro expansion in the "#if !defined(x)" line for the file,
    219   // then the macro could expand to different things in other contexts, we need
    220   // to disable the optimization in this case.
    221   if (CurPPLexer) CurPPLexer->MIOpt.ExpandedMacro();
    222 
    223   // If this is a builtin macro, like __LINE__ or _Pragma, handle it specially.
    224   if (MI->isBuiltinMacro()) {
    225     if (Callbacks) Callbacks->MacroExpands(Identifier, MD,
    226                                            Identifier.getLocation(),/*Args=*/0);
    227     ExpandBuiltinMacro(Identifier);
    228     return false;
    229   }
    230 
    231   /// Args - If this is a function-like macro expansion, this contains,
    232   /// for each macro argument, the list of tokens that were provided to the
    233   /// invocation.
    234   MacroArgs *Args = 0;
    235 
    236   // Remember where the end of the expansion occurred.  For an object-like
    237   // macro, this is the identifier.  For a function-like macro, this is the ')'.
    238   SourceLocation ExpansionEnd = Identifier.getLocation();
    239 
    240   // If this is a function-like macro, read the arguments.
    241   if (MI->isFunctionLike()) {
    242     // C99 6.10.3p10: If the preprocessing token immediately after the macro
    243     // name isn't a '(', this macro should not be expanded.
    244     if (!isNextPPTokenLParen())
    245       return true;
    246 
    247     // Remember that we are now parsing the arguments to a macro invocation.
    248     // Preprocessor directives used inside macro arguments are not portable, and
    249     // this enables the warning.
    250     InMacroArgs = true;
    251     Args = ReadFunctionLikeMacroArgs(Identifier, MI, ExpansionEnd);
    252 
    253     // Finished parsing args.
    254     InMacroArgs = false;
    255 
    256     // If there was an error parsing the arguments, bail out.
    257     if (Args == 0) return false;
    258 
    259     ++NumFnMacroExpanded;
    260   } else {
    261     ++NumMacroExpanded;
    262   }
    263 
    264   // Notice that this macro has been used.
    265   markMacroAsUsed(MI);
    266 
    267   // Remember where the token is expanded.
    268   SourceLocation ExpandLoc = Identifier.getLocation();
    269   SourceRange ExpansionRange(ExpandLoc, ExpansionEnd);
    270 
    271   if (Callbacks) {
    272     if (InMacroArgs) {
    273       // We can have macro expansion inside a conditional directive while
    274       // reading the function macro arguments. To ensure, in that case, that
    275       // MacroExpands callbacks still happen in source order, queue this
    276       // callback to have it happen after the function macro callback.
    277       DelayedMacroExpandsCallbacks.push_back(
    278                               MacroExpandsInfo(Identifier, MD, ExpansionRange));
    279     } else {
    280       Callbacks->MacroExpands(Identifier, MD, ExpansionRange, Args);
    281       if (!DelayedMacroExpandsCallbacks.empty()) {
    282         for (unsigned i=0, e = DelayedMacroExpandsCallbacks.size(); i!=e; ++i) {
    283           MacroExpandsInfo &Info = DelayedMacroExpandsCallbacks[i];
    284           // FIXME: We lose macro args info with delayed callback.
    285           Callbacks->MacroExpands(Info.Tok, Info.MD, Info.Range, /*Args=*/0);
    286         }
    287         DelayedMacroExpandsCallbacks.clear();
    288       }
    289     }
    290   }
    291 
    292   // If the macro definition is ambiguous, complain.
    293   if (Def.getDirective()->isAmbiguous()) {
    294     Diag(Identifier, diag::warn_pp_ambiguous_macro)
    295       << Identifier.getIdentifierInfo();
    296     Diag(MI->getDefinitionLoc(), diag::note_pp_ambiguous_macro_chosen)
    297       << Identifier.getIdentifierInfo();
    298     for (MacroDirective::DefInfo PrevDef = Def.getPreviousDefinition();
    299          PrevDef && !PrevDef.isUndefined();
    300          PrevDef = PrevDef.getPreviousDefinition()) {
    301       if (PrevDef.getDirective()->isAmbiguous()) {
    302         Diag(PrevDef.getMacroInfo()->getDefinitionLoc(),
    303              diag::note_pp_ambiguous_macro_other)
    304           << Identifier.getIdentifierInfo();
    305       }
    306     }
    307   }
    308 
    309   // If we started lexing a macro, enter the macro expansion body.
    310 
    311   // If this macro expands to no tokens, don't bother to push it onto the
    312   // expansion stack, only to take it right back off.
    313   if (MI->getNumTokens() == 0) {
    314     // No need for arg info.
    315     if (Args) Args->destroy(*this);
    316 
    317     // Ignore this macro use, just return the next token in the current
    318     // buffer.
    319     bool HadLeadingSpace = Identifier.hasLeadingSpace();
    320     bool IsAtStartOfLine = Identifier.isAtStartOfLine();
    321 
    322     Lex(Identifier);
    323 
    324     // If the identifier isn't on some OTHER line, inherit the leading
    325     // whitespace/first-on-a-line property of this token.  This handles
    326     // stuff like "! XX," -> "! ," and "   XX," -> "    ,", when XX is
    327     // empty.
    328     if (!Identifier.isAtStartOfLine()) {
    329       if (IsAtStartOfLine) Identifier.setFlag(Token::StartOfLine);
    330       if (HadLeadingSpace) Identifier.setFlag(Token::LeadingSpace);
    331     }
    332     Identifier.setFlag(Token::LeadingEmptyMacro);
    333     ++NumFastMacroExpanded;
    334     return false;
    335 
    336   } else if (MI->getNumTokens() == 1 &&
    337              isTrivialSingleTokenExpansion(MI, Identifier.getIdentifierInfo(),
    338                                            *this)) {
    339     // Otherwise, if this macro expands into a single trivially-expanded
    340     // token: expand it now.  This handles common cases like
    341     // "#define VAL 42".
    342 
    343     // No need for arg info.
    344     if (Args) Args->destroy(*this);
    345 
    346     // Propagate the isAtStartOfLine/hasLeadingSpace markers of the macro
    347     // identifier to the expanded token.
    348     bool isAtStartOfLine = Identifier.isAtStartOfLine();
    349     bool hasLeadingSpace = Identifier.hasLeadingSpace();
    350 
    351     // Replace the result token.
    352     Identifier = MI->getReplacementToken(0);
    353 
    354     // Restore the StartOfLine/LeadingSpace markers.
    355     Identifier.setFlagValue(Token::StartOfLine , isAtStartOfLine);
    356     Identifier.setFlagValue(Token::LeadingSpace, hasLeadingSpace);
    357 
    358     // Update the tokens location to include both its expansion and physical
    359     // locations.
    360     SourceLocation Loc =
    361       SourceMgr.createExpansionLoc(Identifier.getLocation(), ExpandLoc,
    362                                    ExpansionEnd,Identifier.getLength());
    363     Identifier.setLocation(Loc);
    364 
    365     // If this is a disabled macro or #define X X, we must mark the result as
    366     // unexpandable.
    367     if (IdentifierInfo *NewII = Identifier.getIdentifierInfo()) {
    368       if (MacroInfo *NewMI = getMacroInfo(NewII))
    369         if (!NewMI->isEnabled() || NewMI == MI) {
    370           Identifier.setFlag(Token::DisableExpand);
    371           // Don't warn for "#define X X" like "#define bool bool" from
    372           // stdbool.h.
    373           if (NewMI != MI || MI->isFunctionLike())
    374             Diag(Identifier, diag::pp_disabled_macro_expansion);
    375         }
    376     }
    377 
    378     // Since this is not an identifier token, it can't be macro expanded, so
    379     // we're done.
    380     ++NumFastMacroExpanded;
    381     return false;
    382   }
    383 
    384   // Start expanding the macro.
    385   EnterMacro(Identifier, ExpansionEnd, MI, Args);
    386 
    387   // Now that the macro is at the top of the include stack, ask the
    388   // preprocessor to read the next token from it.
    389   Lex(Identifier);
    390   return false;
    391 }
    392 
    393 enum Bracket {
    394   Brace,
    395   Paren
    396 };
    397 
    398 /// CheckMatchedBrackets - Returns true if the braces and parentheses in the
    399 /// token vector are properly nested.
    400 static bool CheckMatchedBrackets(const SmallVectorImpl<Token> &Tokens) {
    401   SmallVector<Bracket, 8> Brackets;
    402   for (SmallVectorImpl<Token>::const_iterator I = Tokens.begin(),
    403                                               E = Tokens.end();
    404        I != E; ++I) {
    405     if (I->is(tok::l_paren)) {
    406       Brackets.push_back(Paren);
    407     } else if (I->is(tok::r_paren)) {
    408       if (Brackets.empty() || Brackets.back() == Brace)
    409         return false;
    410       Brackets.pop_back();
    411     } else if (I->is(tok::l_brace)) {
    412       Brackets.push_back(Brace);
    413     } else if (I->is(tok::r_brace)) {
    414       if (Brackets.empty() || Brackets.back() == Paren)
    415         return false;
    416       Brackets.pop_back();
    417     }
    418   }
    419   if (!Brackets.empty())
    420     return false;
    421   return true;
    422 }
    423 
    424 /// GenerateNewArgTokens - Returns true if OldTokens can be converted to a new
    425 /// vector of tokens in NewTokens.  The new number of arguments will be placed
    426 /// in NumArgs and the ranges which need to surrounded in parentheses will be
    427 /// in ParenHints.
    428 /// Returns false if the token stream cannot be changed.  If this is because
    429 /// of an initializer list starting a macro argument, the range of those
    430 /// initializer lists will be place in InitLists.
    431 static bool GenerateNewArgTokens(Preprocessor &PP,
    432                                  SmallVectorImpl<Token> &OldTokens,
    433                                  SmallVectorImpl<Token> &NewTokens,
    434                                  unsigned &NumArgs,
    435                                  SmallVectorImpl<SourceRange> &ParenHints,
    436                                  SmallVectorImpl<SourceRange> &InitLists) {
    437   if (!CheckMatchedBrackets(OldTokens))
    438     return false;
    439 
    440   // Once it is known that the brackets are matched, only a simple count of the
    441   // braces is needed.
    442   unsigned Braces = 0;
    443 
    444   // First token of a new macro argument.
    445   SmallVectorImpl<Token>::iterator ArgStartIterator = OldTokens.begin();
    446 
    447   // First closing brace in a new macro argument.  Used to generate
    448   // SourceRanges for InitLists.
    449   SmallVectorImpl<Token>::iterator ClosingBrace = OldTokens.end();
    450   NumArgs = 0;
    451   Token TempToken;
    452   // Set to true when a macro separator token is found inside a braced list.
    453   // If true, the fixed argument spans multiple old arguments and ParenHints
    454   // will be updated.
    455   bool FoundSeparatorToken = false;
    456   for (SmallVectorImpl<Token>::iterator I = OldTokens.begin(),
    457                                         E = OldTokens.end();
    458        I != E; ++I) {
    459     if (I->is(tok::l_brace)) {
    460       ++Braces;
    461     } else if (I->is(tok::r_brace)) {
    462       --Braces;
    463       if (Braces == 0 && ClosingBrace == E && FoundSeparatorToken)
    464         ClosingBrace = I;
    465     } else if (I->is(tok::eof)) {
    466       // EOF token is used to separate macro arguments
    467       if (Braces != 0) {
    468         // Assume comma separator is actually braced list separator and change
    469         // it back to a comma.
    470         FoundSeparatorToken = true;
    471         I->setKind(tok::comma);
    472         I->setLength(1);
    473       } else { // Braces == 0
    474         // Separator token still separates arguments.
    475         ++NumArgs;
    476 
    477         // If the argument starts with a brace, it can't be fixed with
    478         // parentheses.  A different diagnostic will be given.
    479         if (FoundSeparatorToken && ArgStartIterator->is(tok::l_brace)) {
    480           InitLists.push_back(
    481               SourceRange(ArgStartIterator->getLocation(),
    482                           PP.getLocForEndOfToken(ClosingBrace->getLocation())));
    483           ClosingBrace = E;
    484         }
    485 
    486         // Add left paren
    487         if (FoundSeparatorToken) {
    488           TempToken.startToken();
    489           TempToken.setKind(tok::l_paren);
    490           TempToken.setLocation(ArgStartIterator->getLocation());
    491           TempToken.setLength(0);
    492           NewTokens.push_back(TempToken);
    493         }
    494 
    495         // Copy over argument tokens
    496         NewTokens.insert(NewTokens.end(), ArgStartIterator, I);
    497 
    498         // Add right paren and store the paren locations in ParenHints
    499         if (FoundSeparatorToken) {
    500           SourceLocation Loc = PP.getLocForEndOfToken((I - 1)->getLocation());
    501           TempToken.startToken();
    502           TempToken.setKind(tok::r_paren);
    503           TempToken.setLocation(Loc);
    504           TempToken.setLength(0);
    505           NewTokens.push_back(TempToken);
    506           ParenHints.push_back(SourceRange(ArgStartIterator->getLocation(),
    507                                            Loc));
    508         }
    509 
    510         // Copy separator token
    511         NewTokens.push_back(*I);
    512 
    513         // Reset values
    514         ArgStartIterator = I + 1;
    515         FoundSeparatorToken = false;
    516       }
    517     }
    518   }
    519 
    520   return !ParenHints.empty() && InitLists.empty();
    521 }
    522 
    523 /// ReadFunctionLikeMacroArgs - After reading "MACRO" and knowing that the next
    524 /// token is the '(' of the macro, this method is invoked to read all of the
    525 /// actual arguments specified for the macro invocation.  This returns null on
    526 /// error.
    527 MacroArgs *Preprocessor::ReadFunctionLikeMacroArgs(Token &MacroName,
    528                                                    MacroInfo *MI,
    529                                                    SourceLocation &MacroEnd) {
    530   // The number of fixed arguments to parse.
    531   unsigned NumFixedArgsLeft = MI->getNumArgs();
    532   bool isVariadic = MI->isVariadic();
    533 
    534   // Outer loop, while there are more arguments, keep reading them.
    535   Token Tok;
    536 
    537   // Read arguments as unexpanded tokens.  This avoids issues, e.g., where
    538   // an argument value in a macro could expand to ',' or '(' or ')'.
    539   LexUnexpandedToken(Tok);
    540   assert(Tok.is(tok::l_paren) && "Error computing l-paren-ness?");
    541 
    542   // ArgTokens - Build up a list of tokens that make up each argument.  Each
    543   // argument is separated by an EOF token.  Use a SmallVector so we can avoid
    544   // heap allocations in the common case.
    545   SmallVector<Token, 64> ArgTokens;
    546   bool ContainsCodeCompletionTok = false;
    547 
    548   SourceLocation TooManyArgsLoc;
    549 
    550   unsigned NumActuals = 0;
    551   while (Tok.isNot(tok::r_paren)) {
    552     if (ContainsCodeCompletionTok && (Tok.is(tok::eof) || Tok.is(tok::eod)))
    553       break;
    554 
    555     assert((Tok.is(tok::l_paren) || Tok.is(tok::comma)) &&
    556            "only expect argument separators here");
    557 
    558     unsigned ArgTokenStart = ArgTokens.size();
    559     SourceLocation ArgStartLoc = Tok.getLocation();
    560 
    561     // C99 6.10.3p11: Keep track of the number of l_parens we have seen.  Note
    562     // that we already consumed the first one.
    563     unsigned NumParens = 0;
    564 
    565     while (1) {
    566       // Read arguments as unexpanded tokens.  This avoids issues, e.g., where
    567       // an argument value in a macro could expand to ',' or '(' or ')'.
    568       LexUnexpandedToken(Tok);
    569 
    570       if (Tok.is(tok::eof) || Tok.is(tok::eod)) { // "#if f(<eof>" & "#if f(\n"
    571         if (!ContainsCodeCompletionTok) {
    572           Diag(MacroName, diag::err_unterm_macro_invoc);
    573           Diag(MI->getDefinitionLoc(), diag::note_macro_here)
    574             << MacroName.getIdentifierInfo();
    575           // Do not lose the EOF/EOD.  Return it to the client.
    576           MacroName = Tok;
    577           return 0;
    578         } else {
    579           // Do not lose the EOF/EOD.
    580           Token *Toks = new Token[1];
    581           Toks[0] = Tok;
    582           EnterTokenStream(Toks, 1, true, true);
    583           break;
    584         }
    585       } else if (Tok.is(tok::r_paren)) {
    586         // If we found the ) token, the macro arg list is done.
    587         if (NumParens-- == 0) {
    588           MacroEnd = Tok.getLocation();
    589           break;
    590         }
    591       } else if (Tok.is(tok::l_paren)) {
    592         ++NumParens;
    593       } else if (Tok.is(tok::comma) && NumParens == 0 &&
    594                  !(Tok.getFlags() & Token::IgnoredComma)) {
    595         // In Microsoft-compatibility mode, single commas from nested macro
    596         // expansions should not be considered as argument separators. We test
    597         // for this with the IgnoredComma token flag above.
    598 
    599         // Comma ends this argument if there are more fixed arguments expected.
    600         // However, if this is a variadic macro, and this is part of the
    601         // variadic part, then the comma is just an argument token.
    602         if (!isVariadic) break;
    603         if (NumFixedArgsLeft > 1)
    604           break;
    605       } else if (Tok.is(tok::comment) && !KeepMacroComments) {
    606         // If this is a comment token in the argument list and we're just in
    607         // -C mode (not -CC mode), discard the comment.
    608         continue;
    609       } else if (Tok.getIdentifierInfo() != 0) {
    610         // Reading macro arguments can cause macros that we are currently
    611         // expanding from to be popped off the expansion stack.  Doing so causes
    612         // them to be reenabled for expansion.  Here we record whether any
    613         // identifiers we lex as macro arguments correspond to disabled macros.
    614         // If so, we mark the token as noexpand.  This is a subtle aspect of
    615         // C99 6.10.3.4p2.
    616         if (MacroInfo *MI = getMacroInfo(Tok.getIdentifierInfo()))
    617           if (!MI->isEnabled())
    618             Tok.setFlag(Token::DisableExpand);
    619       } else if (Tok.is(tok::code_completion)) {
    620         ContainsCodeCompletionTok = true;
    621         if (CodeComplete)
    622           CodeComplete->CodeCompleteMacroArgument(MacroName.getIdentifierInfo(),
    623                                                   MI, NumActuals);
    624         // Don't mark that we reached the code-completion point because the
    625         // parser is going to handle the token and there will be another
    626         // code-completion callback.
    627       }
    628 
    629       ArgTokens.push_back(Tok);
    630     }
    631 
    632     // If this was an empty argument list foo(), don't add this as an empty
    633     // argument.
    634     if (ArgTokens.empty() && Tok.getKind() == tok::r_paren)
    635       break;
    636 
    637     // If this is not a variadic macro, and too many args were specified, emit
    638     // an error.
    639     if (!isVariadic && NumFixedArgsLeft == 0 && TooManyArgsLoc.isInvalid()) {
    640       if (ArgTokens.size() != ArgTokenStart)
    641         TooManyArgsLoc = ArgTokens[ArgTokenStart].getLocation();
    642       else
    643         TooManyArgsLoc = ArgStartLoc;
    644     }
    645 
    646     // Empty arguments are standard in C99 and C++0x, and are supported as an
    647     // extension in other modes.
    648     if (ArgTokens.size() == ArgTokenStart && !LangOpts.C99)
    649       Diag(Tok, LangOpts.CPlusPlus11 ?
    650            diag::warn_cxx98_compat_empty_fnmacro_arg :
    651            diag::ext_empty_fnmacro_arg);
    652 
    653     // Add a marker EOF token to the end of the token list for this argument.
    654     Token EOFTok;
    655     EOFTok.startToken();
    656     EOFTok.setKind(tok::eof);
    657     EOFTok.setLocation(Tok.getLocation());
    658     EOFTok.setLength(0);
    659     ArgTokens.push_back(EOFTok);
    660     ++NumActuals;
    661     if (!ContainsCodeCompletionTok && NumFixedArgsLeft != 0)
    662       --NumFixedArgsLeft;
    663   }
    664 
    665   // Okay, we either found the r_paren.  Check to see if we parsed too few
    666   // arguments.
    667   unsigned MinArgsExpected = MI->getNumArgs();
    668 
    669   // If this is not a variadic macro, and too many args were specified, emit
    670   // an error.
    671   if (!isVariadic && NumActuals > MinArgsExpected &&
    672       !ContainsCodeCompletionTok) {
    673     // Emit the diagnostic at the macro name in case there is a missing ).
    674     // Emitting it at the , could be far away from the macro name.
    675     Diag(TooManyArgsLoc, diag::err_too_many_args_in_macro_invoc);
    676     Diag(MI->getDefinitionLoc(), diag::note_macro_here)
    677       << MacroName.getIdentifierInfo();
    678 
    679     // Commas from braced initializer lists will be treated as argument
    680     // separators inside macros.  Attempt to correct for this with parentheses.
    681     // TODO: See if this can be generalized to angle brackets for templates
    682     // inside macro arguments.
    683 
    684     SmallVector<Token, 4> FixedArgTokens;
    685     unsigned FixedNumArgs = 0;
    686     SmallVector<SourceRange, 4> ParenHints, InitLists;
    687     if (!GenerateNewArgTokens(*this, ArgTokens, FixedArgTokens, FixedNumArgs,
    688                               ParenHints, InitLists)) {
    689       if (!InitLists.empty()) {
    690         DiagnosticBuilder DB =
    691             Diag(MacroName,
    692                  diag::note_init_list_at_beginning_of_macro_argument);
    693         for (SmallVector<SourceRange, 4>::iterator
    694                  Range = InitLists.begin(), RangeEnd = InitLists.end();
    695                  Range != RangeEnd; ++Range) {
    696           if (DB.hasMaxRanges())
    697             break;
    698           DB << *Range;
    699         }
    700       }
    701       return 0;
    702     }
    703     if (FixedNumArgs != MinArgsExpected)
    704       return 0;
    705 
    706     DiagnosticBuilder DB = Diag(MacroName, diag::note_suggest_parens_for_macro);
    707     for (SmallVector<SourceRange, 4>::iterator
    708              ParenLocation = ParenHints.begin(), ParenEnd = ParenHints.end();
    709          ParenLocation != ParenEnd; ++ParenLocation) {
    710       if (DB.hasMaxFixItHints())
    711         break;
    712       DB << FixItHint::CreateInsertion(ParenLocation->getBegin(), "(");
    713       if (DB.hasMaxFixItHints())
    714         break;
    715       DB << FixItHint::CreateInsertion(ParenLocation->getEnd(), ")");
    716     }
    717     ArgTokens.swap(FixedArgTokens);
    718     NumActuals = FixedNumArgs;
    719   }
    720 
    721   // See MacroArgs instance var for description of this.
    722   bool isVarargsElided = false;
    723 
    724   if (ContainsCodeCompletionTok) {
    725     // Recover from not-fully-formed macro invocation during code-completion.
    726     Token EOFTok;
    727     EOFTok.startToken();
    728     EOFTok.setKind(tok::eof);
    729     EOFTok.setLocation(Tok.getLocation());
    730     EOFTok.setLength(0);
    731     for (; NumActuals < MinArgsExpected; ++NumActuals)
    732       ArgTokens.push_back(EOFTok);
    733   }
    734 
    735   if (NumActuals < MinArgsExpected) {
    736     // There are several cases where too few arguments is ok, handle them now.
    737     if (NumActuals == 0 && MinArgsExpected == 1) {
    738       // #define A(X)  or  #define A(...)   ---> A()
    739 
    740       // If there is exactly one argument, and that argument is missing,
    741       // then we have an empty "()" argument empty list.  This is fine, even if
    742       // the macro expects one argument (the argument is just empty).
    743       isVarargsElided = MI->isVariadic();
    744     } else if (MI->isVariadic() &&
    745                (NumActuals+1 == MinArgsExpected ||  // A(x, ...) -> A(X)
    746                 (NumActuals == 0 && MinArgsExpected == 2))) {// A(x,...) -> A()
    747       // Varargs where the named vararg parameter is missing: OK as extension.
    748       //   #define A(x, ...)
    749       //   A("blah")
    750       //
    751       // If the macro contains the comma pasting extension, the diagnostic
    752       // is suppressed; we know we'll get another diagnostic later.
    753       if (!MI->hasCommaPasting()) {
    754         Diag(Tok, diag::ext_missing_varargs_arg);
    755         Diag(MI->getDefinitionLoc(), diag::note_macro_here)
    756           << MacroName.getIdentifierInfo();
    757       }
    758 
    759       // Remember this occurred, allowing us to elide the comma when used for
    760       // cases like:
    761       //   #define A(x, foo...) blah(a, ## foo)
    762       //   #define B(x, ...) blah(a, ## __VA_ARGS__)
    763       //   #define C(...) blah(a, ## __VA_ARGS__)
    764       //  A(x) B(x) C()
    765       isVarargsElided = true;
    766     } else if (!ContainsCodeCompletionTok) {
    767       // Otherwise, emit the error.
    768       Diag(Tok, diag::err_too_few_args_in_macro_invoc);
    769       Diag(MI->getDefinitionLoc(), diag::note_macro_here)
    770         << MacroName.getIdentifierInfo();
    771       return 0;
    772     }
    773 
    774     // Add a marker EOF token to the end of the token list for this argument.
    775     SourceLocation EndLoc = Tok.getLocation();
    776     Tok.startToken();
    777     Tok.setKind(tok::eof);
    778     Tok.setLocation(EndLoc);
    779     Tok.setLength(0);
    780     ArgTokens.push_back(Tok);
    781 
    782     // If we expect two arguments, add both as empty.
    783     if (NumActuals == 0 && MinArgsExpected == 2)
    784       ArgTokens.push_back(Tok);
    785 
    786   } else if (NumActuals > MinArgsExpected && !MI->isVariadic() &&
    787              !ContainsCodeCompletionTok) {
    788     // Emit the diagnostic at the macro name in case there is a missing ).
    789     // Emitting it at the , could be far away from the macro name.
    790     Diag(MacroName, diag::err_too_many_args_in_macro_invoc);
    791     Diag(MI->getDefinitionLoc(), diag::note_macro_here)
    792       << MacroName.getIdentifierInfo();
    793     return 0;
    794   }
    795 
    796   return MacroArgs::create(MI, ArgTokens, isVarargsElided, *this);
    797 }
    798 
    799 /// \brief Keeps macro expanded tokens for TokenLexers.
    800 //
    801 /// Works like a stack; a TokenLexer adds the macro expanded tokens that is
    802 /// going to lex in the cache and when it finishes the tokens are removed
    803 /// from the end of the cache.
    804 Token *Preprocessor::cacheMacroExpandedTokens(TokenLexer *tokLexer,
    805                                               ArrayRef<Token> tokens) {
    806   assert(tokLexer);
    807   if (tokens.empty())
    808     return 0;
    809 
    810   size_t newIndex = MacroExpandedTokens.size();
    811   bool cacheNeedsToGrow = tokens.size() >
    812                       MacroExpandedTokens.capacity()-MacroExpandedTokens.size();
    813   MacroExpandedTokens.append(tokens.begin(), tokens.end());
    814 
    815   if (cacheNeedsToGrow) {
    816     // Go through all the TokenLexers whose 'Tokens' pointer points in the
    817     // buffer and update the pointers to the (potential) new buffer array.
    818     for (unsigned i = 0, e = MacroExpandingLexersStack.size(); i != e; ++i) {
    819       TokenLexer *prevLexer;
    820       size_t tokIndex;
    821       llvm::tie(prevLexer, tokIndex) = MacroExpandingLexersStack[i];
    822       prevLexer->Tokens = MacroExpandedTokens.data() + tokIndex;
    823     }
    824   }
    825 
    826   MacroExpandingLexersStack.push_back(std::make_pair(tokLexer, newIndex));
    827   return MacroExpandedTokens.data() + newIndex;
    828 }
    829 
    830 void Preprocessor::removeCachedMacroExpandedTokensOfLastLexer() {
    831   assert(!MacroExpandingLexersStack.empty());
    832   size_t tokIndex = MacroExpandingLexersStack.back().second;
    833   assert(tokIndex < MacroExpandedTokens.size());
    834   // Pop the cached macro expanded tokens from the end.
    835   MacroExpandedTokens.resize(tokIndex);
    836   MacroExpandingLexersStack.pop_back();
    837 }
    838 
    839 /// ComputeDATE_TIME - Compute the current time, enter it into the specified
    840 /// scratch buffer, then return DATELoc/TIMELoc locations with the position of
    841 /// the identifier tokens inserted.
    842 static void ComputeDATE_TIME(SourceLocation &DATELoc, SourceLocation &TIMELoc,
    843                              Preprocessor &PP) {
    844   time_t TT = time(0);
    845   struct tm *TM = localtime(&TT);
    846 
    847   static const char * const Months[] = {
    848     "Jan","Feb","Mar","Apr","May","Jun","Jul","Aug","Sep","Oct","Nov","Dec"
    849   };
    850 
    851   {
    852     SmallString<32> TmpBuffer;
    853     llvm::raw_svector_ostream TmpStream(TmpBuffer);
    854     TmpStream << llvm::format("\"%s %2d %4d\"", Months[TM->tm_mon],
    855                               TM->tm_mday, TM->tm_year + 1900);
    856     Token TmpTok;
    857     TmpTok.startToken();
    858     PP.CreateString(TmpStream.str(), TmpTok);
    859     DATELoc = TmpTok.getLocation();
    860   }
    861 
    862   {
    863     SmallString<32> TmpBuffer;
    864     llvm::raw_svector_ostream TmpStream(TmpBuffer);
    865     TmpStream << llvm::format("\"%02d:%02d:%02d\"",
    866                               TM->tm_hour, TM->tm_min, TM->tm_sec);
    867     Token TmpTok;
    868     TmpTok.startToken();
    869     PP.CreateString(TmpStream.str(), TmpTok);
    870     TIMELoc = TmpTok.getLocation();
    871   }
    872 }
    873 
    874 
    875 /// HasFeature - Return true if we recognize and implement the feature
    876 /// specified by the identifier as a standard language feature.
    877 static bool HasFeature(const Preprocessor &PP, const IdentifierInfo *II) {
    878   const LangOptions &LangOpts = PP.getLangOpts();
    879   StringRef Feature = II->getName();
    880 
    881   // Normalize the feature name, __foo__ becomes foo.
    882   if (Feature.startswith("__") && Feature.endswith("__") && Feature.size() >= 4)
    883     Feature = Feature.substr(2, Feature.size() - 4);
    884 
    885   return llvm::StringSwitch<bool>(Feature)
    886            .Case("address_sanitizer", LangOpts.Sanitize.Address)
    887            .Case("attribute_analyzer_noreturn", true)
    888            .Case("attribute_availability", true)
    889            .Case("attribute_availability_with_message", true)
    890            .Case("attribute_cf_returns_not_retained", true)
    891            .Case("attribute_cf_returns_retained", true)
    892            .Case("attribute_deprecated_with_message", true)
    893            .Case("attribute_ext_vector_type", true)
    894            .Case("attribute_ns_returns_not_retained", true)
    895            .Case("attribute_ns_returns_retained", true)
    896            .Case("attribute_ns_consumes_self", true)
    897            .Case("attribute_ns_consumed", true)
    898            .Case("attribute_cf_consumed", true)
    899            .Case("attribute_objc_ivar_unused", true)
    900            .Case("attribute_objc_method_family", true)
    901            .Case("attribute_overloadable", true)
    902            .Case("attribute_unavailable_with_message", true)
    903            .Case("attribute_unused_on_fields", true)
    904            .Case("blocks", LangOpts.Blocks)
    905            .Case("c_thread_safety_attributes", true)
    906            .Case("cxx_exceptions", LangOpts.Exceptions)
    907            .Case("cxx_rtti", LangOpts.RTTI)
    908            .Case("enumerator_attributes", true)
    909            .Case("memory_sanitizer", LangOpts.Sanitize.Memory)
    910            .Case("thread_sanitizer", LangOpts.Sanitize.Thread)
    911            // Objective-C features
    912            .Case("objc_arr", LangOpts.ObjCAutoRefCount) // FIXME: REMOVE?
    913            .Case("objc_arc", LangOpts.ObjCAutoRefCount)
    914            .Case("objc_arc_weak", LangOpts.ObjCARCWeak)
    915            .Case("objc_default_synthesize_properties", LangOpts.ObjC2)
    916            .Case("objc_fixed_enum", LangOpts.ObjC2)
    917            .Case("objc_instancetype", LangOpts.ObjC2)
    918            .Case("objc_modules", LangOpts.ObjC2 && LangOpts.Modules)
    919            .Case("objc_nonfragile_abi", LangOpts.ObjCRuntime.isNonFragile())
    920            .Case("objc_property_explicit_atomic", true) // Does clang support explicit "atomic" keyword?
    921            .Case("objc_weak_class", LangOpts.ObjCRuntime.hasWeakClassImport())
    922            .Case("objc_msg_lookup_stret", LangOpts.ObjCRuntime.getKind() == ObjCRuntime::ObjFW)
    923            .Case("ownership_holds", true)
    924            .Case("ownership_returns", true)
    925            .Case("ownership_takes", true)
    926            .Case("objc_bool", true)
    927            .Case("objc_subscripting", LangOpts.ObjCRuntime.isNonFragile())
    928            .Case("objc_array_literals", LangOpts.ObjC2)
    929            .Case("objc_dictionary_literals", LangOpts.ObjC2)
    930            .Case("objc_boxed_expressions", LangOpts.ObjC2)
    931            .Case("arc_cf_code_audited", true)
    932            // C11 features
    933            .Case("c_alignas", LangOpts.C11)
    934            .Case("c_atomic", LangOpts.C11)
    935            .Case("c_generic_selections", LangOpts.C11)
    936            .Case("c_static_assert", LangOpts.C11)
    937            .Case("c_thread_local",
    938                  LangOpts.C11 && PP.getTargetInfo().isTLSSupported())
    939            // C++11 features
    940            .Case("cxx_access_control_sfinae", LangOpts.CPlusPlus11)
    941            .Case("cxx_alias_templates", LangOpts.CPlusPlus11)
    942            .Case("cxx_alignas", LangOpts.CPlusPlus11)
    943            .Case("cxx_atomic", LangOpts.CPlusPlus11)
    944            .Case("cxx_attributes", LangOpts.CPlusPlus11)
    945            .Case("cxx_auto_type", LangOpts.CPlusPlus11)
    946            .Case("cxx_constexpr", LangOpts.CPlusPlus11)
    947            .Case("cxx_decltype", LangOpts.CPlusPlus11)
    948            .Case("cxx_decltype_incomplete_return_types", LangOpts.CPlusPlus11)
    949            .Case("cxx_default_function_template_args", LangOpts.CPlusPlus11)
    950            .Case("cxx_defaulted_functions", LangOpts.CPlusPlus11)
    951            .Case("cxx_delegating_constructors", LangOpts.CPlusPlus11)
    952            .Case("cxx_deleted_functions", LangOpts.CPlusPlus11)
    953            .Case("cxx_explicit_conversions", LangOpts.CPlusPlus11)
    954            .Case("cxx_generalized_initializers", LangOpts.CPlusPlus11)
    955            .Case("cxx_implicit_moves", LangOpts.CPlusPlus11)
    956            .Case("cxx_inheriting_constructors", LangOpts.CPlusPlus11)
    957            .Case("cxx_inline_namespaces", LangOpts.CPlusPlus11)
    958            .Case("cxx_lambdas", LangOpts.CPlusPlus11)
    959            .Case("cxx_local_type_template_args", LangOpts.CPlusPlus11)
    960            .Case("cxx_nonstatic_member_init", LangOpts.CPlusPlus11)
    961            .Case("cxx_noexcept", LangOpts.CPlusPlus11)
    962            .Case("cxx_nullptr", LangOpts.CPlusPlus11)
    963            .Case("cxx_override_control", LangOpts.CPlusPlus11)
    964            .Case("cxx_range_for", LangOpts.CPlusPlus11)
    965            .Case("cxx_raw_string_literals", LangOpts.CPlusPlus11)
    966            .Case("cxx_reference_qualified_functions", LangOpts.CPlusPlus11)
    967            .Case("cxx_rvalue_references", LangOpts.CPlusPlus11)
    968            .Case("cxx_strong_enums", LangOpts.CPlusPlus11)
    969            .Case("cxx_static_assert", LangOpts.CPlusPlus11)
    970            .Case("cxx_thread_local",
    971                  LangOpts.CPlusPlus11 && PP.getTargetInfo().isTLSSupported())
    972            .Case("cxx_trailing_return", LangOpts.CPlusPlus11)
    973            .Case("cxx_unicode_literals", LangOpts.CPlusPlus11)
    974            .Case("cxx_unrestricted_unions", LangOpts.CPlusPlus11)
    975            .Case("cxx_user_literals", LangOpts.CPlusPlus11)
    976            .Case("cxx_variadic_templates", LangOpts.CPlusPlus11)
    977            // C++1y features
    978            .Case("cxx_aggregate_nsdmi", LangOpts.CPlusPlus1y)
    979            .Case("cxx_binary_literals", LangOpts.CPlusPlus1y)
    980            .Case("cxx_contextual_conversions", LangOpts.CPlusPlus1y)
    981            //.Case("cxx_generic_lambda", LangOpts.CPlusPlus1y)
    982            //.Case("cxx_init_capture", LangOpts.CPlusPlus1y)
    983            .Case("cxx_relaxed_constexpr", LangOpts.CPlusPlus1y)
    984            .Case("cxx_return_type_deduction", LangOpts.CPlusPlus1y)
    985            //.Case("cxx_runtime_array", LangOpts.CPlusPlus1y)
    986            //.Case("cxx_variable_templates", LangOpts.CPlusPlus1y)
    987            // Type traits
    988            .Case("has_nothrow_assign", LangOpts.CPlusPlus)
    989            .Case("has_nothrow_copy", LangOpts.CPlusPlus)
    990            .Case("has_nothrow_constructor", LangOpts.CPlusPlus)
    991            .Case("has_trivial_assign", LangOpts.CPlusPlus)
    992            .Case("has_trivial_copy", LangOpts.CPlusPlus)
    993            .Case("has_trivial_constructor", LangOpts.CPlusPlus)
    994            .Case("has_trivial_destructor", LangOpts.CPlusPlus)
    995            .Case("has_virtual_destructor", LangOpts.CPlusPlus)
    996            .Case("is_abstract", LangOpts.CPlusPlus)
    997            .Case("is_base_of", LangOpts.CPlusPlus)
    998            .Case("is_class", LangOpts.CPlusPlus)
    999            .Case("is_convertible_to", LangOpts.CPlusPlus)
   1000            .Case("is_empty", LangOpts.CPlusPlus)
   1001            .Case("is_enum", LangOpts.CPlusPlus)
   1002            .Case("is_final", LangOpts.CPlusPlus)
   1003            .Case("is_literal", LangOpts.CPlusPlus)
   1004            .Case("is_standard_layout", LangOpts.CPlusPlus)
   1005            .Case("is_pod", LangOpts.CPlusPlus)
   1006            .Case("is_polymorphic", LangOpts.CPlusPlus)
   1007            .Case("is_trivial", LangOpts.CPlusPlus)
   1008            .Case("is_trivially_assignable", LangOpts.CPlusPlus)
   1009            .Case("is_trivially_constructible", LangOpts.CPlusPlus)
   1010            .Case("is_trivially_copyable", LangOpts.CPlusPlus)
   1011            .Case("is_union", LangOpts.CPlusPlus)
   1012            .Case("modules", LangOpts.Modules)
   1013            .Case("tls", PP.getTargetInfo().isTLSSupported())
   1014            .Case("underlying_type", LangOpts.CPlusPlus)
   1015            .Default(false);
   1016 }
   1017 
   1018 /// HasExtension - Return true if we recognize and implement the feature
   1019 /// specified by the identifier, either as an extension or a standard language
   1020 /// feature.
   1021 static bool HasExtension(const Preprocessor &PP, const IdentifierInfo *II) {
   1022   if (HasFeature(PP, II))
   1023     return true;
   1024 
   1025   // If the use of an extension results in an error diagnostic, extensions are
   1026   // effectively unavailable, so just return false here.
   1027   if (PP.getDiagnostics().getExtensionHandlingBehavior() ==
   1028       DiagnosticsEngine::Ext_Error)
   1029     return false;
   1030 
   1031   const LangOptions &LangOpts = PP.getLangOpts();
   1032   StringRef Extension = II->getName();
   1033 
   1034   // Normalize the extension name, __foo__ becomes foo.
   1035   if (Extension.startswith("__") && Extension.endswith("__") &&
   1036       Extension.size() >= 4)
   1037     Extension = Extension.substr(2, Extension.size() - 4);
   1038 
   1039   // Because we inherit the feature list from HasFeature, this string switch
   1040   // must be less restrictive than HasFeature's.
   1041   return llvm::StringSwitch<bool>(Extension)
   1042            // C11 features supported by other languages as extensions.
   1043            .Case("c_alignas", true)
   1044            .Case("c_atomic", true)
   1045            .Case("c_generic_selections", true)
   1046            .Case("c_static_assert", true)
   1047            // C++11 features supported by other languages as extensions.
   1048            .Case("cxx_atomic", LangOpts.CPlusPlus)
   1049            .Case("cxx_deleted_functions", LangOpts.CPlusPlus)
   1050            .Case("cxx_explicit_conversions", LangOpts.CPlusPlus)
   1051            .Case("cxx_inline_namespaces", LangOpts.CPlusPlus)
   1052            .Case("cxx_local_type_template_args", LangOpts.CPlusPlus)
   1053            .Case("cxx_nonstatic_member_init", LangOpts.CPlusPlus)
   1054            .Case("cxx_override_control", LangOpts.CPlusPlus)
   1055            .Case("cxx_range_for", LangOpts.CPlusPlus)
   1056            .Case("cxx_reference_qualified_functions", LangOpts.CPlusPlus)
   1057            .Case("cxx_rvalue_references", LangOpts.CPlusPlus)
   1058            // C++1y features supported by other languages as extensions.
   1059            .Case("cxx_binary_literals", true)
   1060            .Default(false);
   1061 }
   1062 
   1063 /// HasAttribute -  Return true if we recognize and implement the attribute
   1064 /// specified by the given identifier.
   1065 static bool HasAttribute(const IdentifierInfo *II) {
   1066   StringRef Name = II->getName();
   1067   // Normalize the attribute name, __foo__ becomes foo.
   1068   if (Name.startswith("__") && Name.endswith("__") && Name.size() >= 4)
   1069     Name = Name.substr(2, Name.size() - 4);
   1070 
   1071   // FIXME: Do we need to handle namespaces here?
   1072   return llvm::StringSwitch<bool>(Name)
   1073 #include "clang/Lex/AttrSpellings.inc"
   1074         .Default(false);
   1075 }
   1076 
   1077 /// EvaluateHasIncludeCommon - Process a '__has_include("path")'
   1078 /// or '__has_include_next("path")' expression.
   1079 /// Returns true if successful.
   1080 static bool EvaluateHasIncludeCommon(Token &Tok,
   1081                                      IdentifierInfo *II, Preprocessor &PP,
   1082                                      const DirectoryLookup *LookupFrom) {
   1083   // Save the location of the current token.  If a '(' is later found, use
   1084   // that location.  If not, use the end of this location instead.
   1085   SourceLocation LParenLoc = Tok.getLocation();
   1086 
   1087   // These expressions are only allowed within a preprocessor directive.
   1088   if (!PP.isParsingIfOrElifDirective()) {
   1089     PP.Diag(LParenLoc, diag::err_pp_directive_required) << II->getName();
   1090     return false;
   1091   }
   1092 
   1093   // Get '('.
   1094   PP.LexNonComment(Tok);
   1095 
   1096   // Ensure we have a '('.
   1097   if (Tok.isNot(tok::l_paren)) {
   1098     // No '(', use end of last token.
   1099     LParenLoc = PP.getLocForEndOfToken(LParenLoc);
   1100     PP.Diag(LParenLoc, diag::err_pp_missing_lparen) << II->getName();
   1101     // If the next token looks like a filename or the start of one,
   1102     // assume it is and process it as such.
   1103     if (!Tok.is(tok::angle_string_literal) && !Tok.is(tok::string_literal) &&
   1104         !Tok.is(tok::less))
   1105       return false;
   1106   } else {
   1107     // Save '(' location for possible missing ')' message.
   1108     LParenLoc = Tok.getLocation();
   1109 
   1110     if (PP.getCurrentLexer()) {
   1111       // Get the file name.
   1112       PP.getCurrentLexer()->LexIncludeFilename(Tok);
   1113     } else {
   1114       // We're in a macro, so we can't use LexIncludeFilename; just
   1115       // grab the next token.
   1116       PP.Lex(Tok);
   1117     }
   1118   }
   1119 
   1120   // Reserve a buffer to get the spelling.
   1121   SmallString<128> FilenameBuffer;
   1122   StringRef Filename;
   1123   SourceLocation EndLoc;
   1124 
   1125   switch (Tok.getKind()) {
   1126   case tok::eod:
   1127     // If the token kind is EOD, the error has already been diagnosed.
   1128     return false;
   1129 
   1130   case tok::angle_string_literal:
   1131   case tok::string_literal: {
   1132     bool Invalid = false;
   1133     Filename = PP.getSpelling(Tok, FilenameBuffer, &Invalid);
   1134     if (Invalid)
   1135       return false;
   1136     break;
   1137   }
   1138 
   1139   case tok::less:
   1140     // This could be a <foo/bar.h> file coming from a macro expansion.  In this
   1141     // case, glue the tokens together into FilenameBuffer and interpret those.
   1142     FilenameBuffer.push_back('<');
   1143     if (PP.ConcatenateIncludeName(FilenameBuffer, EndLoc)) {
   1144       // Let the caller know a <eod> was found by changing the Token kind.
   1145       Tok.setKind(tok::eod);
   1146       return false;   // Found <eod> but no ">"?  Diagnostic already emitted.
   1147     }
   1148     Filename = FilenameBuffer.str();
   1149     break;
   1150   default:
   1151     PP.Diag(Tok.getLocation(), diag::err_pp_expects_filename);
   1152     return false;
   1153   }
   1154 
   1155   SourceLocation FilenameLoc = Tok.getLocation();
   1156 
   1157   // Get ')'.
   1158   PP.LexNonComment(Tok);
   1159 
   1160   // Ensure we have a trailing ).
   1161   if (Tok.isNot(tok::r_paren)) {
   1162     PP.Diag(PP.getLocForEndOfToken(FilenameLoc), diag::err_pp_missing_rparen)
   1163         << II->getName();
   1164     PP.Diag(LParenLoc, diag::note_matching) << "(";
   1165     return false;
   1166   }
   1167 
   1168   bool isAngled = PP.GetIncludeFilenameSpelling(Tok.getLocation(), Filename);
   1169   // If GetIncludeFilenameSpelling set the start ptr to null, there was an
   1170   // error.
   1171   if (Filename.empty())
   1172     return false;
   1173 
   1174   // Search include directories.
   1175   const DirectoryLookup *CurDir;
   1176   const FileEntry *File =
   1177       PP.LookupFile(FilenameLoc, Filename, isAngled, LookupFrom, CurDir, NULL,
   1178                     NULL, NULL);
   1179 
   1180   // Get the result value.  A result of true means the file exists.
   1181   return File != 0;
   1182 }
   1183 
   1184 /// EvaluateHasInclude - Process a '__has_include("path")' expression.
   1185 /// Returns true if successful.
   1186 static bool EvaluateHasInclude(Token &Tok, IdentifierInfo *II,
   1187                                Preprocessor &PP) {
   1188   return EvaluateHasIncludeCommon(Tok, II, PP, NULL);
   1189 }
   1190 
   1191 /// EvaluateHasIncludeNext - Process '__has_include_next("path")' expression.
   1192 /// Returns true if successful.
   1193 static bool EvaluateHasIncludeNext(Token &Tok,
   1194                                    IdentifierInfo *II, Preprocessor &PP) {
   1195   // __has_include_next is like __has_include, except that we start
   1196   // searching after the current found directory.  If we can't do this,
   1197   // issue a diagnostic.
   1198   const DirectoryLookup *Lookup = PP.GetCurDirLookup();
   1199   if (PP.isInPrimaryFile()) {
   1200     Lookup = 0;
   1201     PP.Diag(Tok, diag::pp_include_next_in_primary);
   1202   } else if (Lookup == 0) {
   1203     PP.Diag(Tok, diag::pp_include_next_absolute_path);
   1204   } else {
   1205     // Start looking up in the next directory.
   1206     ++Lookup;
   1207   }
   1208 
   1209   return EvaluateHasIncludeCommon(Tok, II, PP, Lookup);
   1210 }
   1211 
   1212 /// \brief Process __building_module(identifier) expression.
   1213 /// \returns true if we are building the named module, false otherwise.
   1214 static bool EvaluateBuildingModule(Token &Tok,
   1215                                    IdentifierInfo *II, Preprocessor &PP) {
   1216   // Get '('.
   1217   PP.LexNonComment(Tok);
   1218 
   1219   // Ensure we have a '('.
   1220   if (Tok.isNot(tok::l_paren)) {
   1221     PP.Diag(Tok.getLocation(), diag::err_pp_missing_lparen) << II->getName();
   1222     return false;
   1223   }
   1224 
   1225   // Save '(' location for possible missing ')' message.
   1226   SourceLocation LParenLoc = Tok.getLocation();
   1227 
   1228   // Get the module name.
   1229   PP.LexNonComment(Tok);
   1230 
   1231   // Ensure that we have an identifier.
   1232   if (Tok.isNot(tok::identifier)) {
   1233     PP.Diag(Tok.getLocation(), diag::err_expected_id_building_module);
   1234     return false;
   1235   }
   1236 
   1237   bool Result
   1238     = Tok.getIdentifierInfo()->getName() == PP.getLangOpts().CurrentModule;
   1239 
   1240   // Get ')'.
   1241   PP.LexNonComment(Tok);
   1242 
   1243   // Ensure we have a trailing ).
   1244   if (Tok.isNot(tok::r_paren)) {
   1245     PP.Diag(Tok.getLocation(), diag::err_pp_missing_rparen) << II->getName();
   1246     PP.Diag(LParenLoc, diag::note_matching) << "(";
   1247     return false;
   1248   }
   1249 
   1250   return Result;
   1251 }
   1252 
   1253 /// ExpandBuiltinMacro - If an identifier token is read that is to be expanded
   1254 /// as a builtin macro, handle it and return the next token as 'Tok'.
   1255 void Preprocessor::ExpandBuiltinMacro(Token &Tok) {
   1256   // Figure out which token this is.
   1257   IdentifierInfo *II = Tok.getIdentifierInfo();
   1258   assert(II && "Can't be a macro without id info!");
   1259 
   1260   // If this is an _Pragma or Microsoft __pragma directive, expand it,
   1261   // invoke the pragma handler, then lex the token after it.
   1262   if (II == Ident_Pragma)
   1263     return Handle_Pragma(Tok);
   1264   else if (II == Ident__pragma) // in non-MS mode this is null
   1265     return HandleMicrosoft__pragma(Tok);
   1266 
   1267   ++NumBuiltinMacroExpanded;
   1268 
   1269   SmallString<128> TmpBuffer;
   1270   llvm::raw_svector_ostream OS(TmpBuffer);
   1271 
   1272   // Set up the return result.
   1273   Tok.setIdentifierInfo(0);
   1274   Tok.clearFlag(Token::NeedsCleaning);
   1275 
   1276   if (II == Ident__LINE__) {
   1277     // C99 6.10.8: "__LINE__: The presumed line number (within the current
   1278     // source file) of the current source line (an integer constant)".  This can
   1279     // be affected by #line.
   1280     SourceLocation Loc = Tok.getLocation();
   1281 
   1282     // Advance to the location of the first _, this might not be the first byte
   1283     // of the token if it starts with an escaped newline.
   1284     Loc = AdvanceToTokenCharacter(Loc, 0);
   1285 
   1286     // One wrinkle here is that GCC expands __LINE__ to location of the *end* of
   1287     // a macro expansion.  This doesn't matter for object-like macros, but
   1288     // can matter for a function-like macro that expands to contain __LINE__.
   1289     // Skip down through expansion points until we find a file loc for the
   1290     // end of the expansion history.
   1291     Loc = SourceMgr.getExpansionRange(Loc).second;
   1292     PresumedLoc PLoc = SourceMgr.getPresumedLoc(Loc);
   1293 
   1294     // __LINE__ expands to a simple numeric value.
   1295     OS << (PLoc.isValid()? PLoc.getLine() : 1);
   1296     Tok.setKind(tok::numeric_constant);
   1297   } else if (II == Ident__FILE__ || II == Ident__BASE_FILE__) {
   1298     // C99 6.10.8: "__FILE__: The presumed name of the current source file (a
   1299     // character string literal)". This can be affected by #line.
   1300     PresumedLoc PLoc = SourceMgr.getPresumedLoc(Tok.getLocation());
   1301 
   1302     // __BASE_FILE__ is a GNU extension that returns the top of the presumed
   1303     // #include stack instead of the current file.
   1304     if (II == Ident__BASE_FILE__ && PLoc.isValid()) {
   1305       SourceLocation NextLoc = PLoc.getIncludeLoc();
   1306       while (NextLoc.isValid()) {
   1307         PLoc = SourceMgr.getPresumedLoc(NextLoc);
   1308         if (PLoc.isInvalid())
   1309           break;
   1310 
   1311         NextLoc = PLoc.getIncludeLoc();
   1312       }
   1313     }
   1314 
   1315     // Escape this filename.  Turn '\' -> '\\' '"' -> '\"'
   1316     SmallString<128> FN;
   1317     if (PLoc.isValid()) {
   1318       FN += PLoc.getFilename();
   1319       Lexer::Stringify(FN);
   1320       OS << '"' << FN.str() << '"';
   1321     }
   1322     Tok.setKind(tok::string_literal);
   1323   } else if (II == Ident__DATE__) {
   1324     if (!DATELoc.isValid())
   1325       ComputeDATE_TIME(DATELoc, TIMELoc, *this);
   1326     Tok.setKind(tok::string_literal);
   1327     Tok.setLength(strlen("\"Mmm dd yyyy\""));
   1328     Tok.setLocation(SourceMgr.createExpansionLoc(DATELoc, Tok.getLocation(),
   1329                                                  Tok.getLocation(),
   1330                                                  Tok.getLength()));
   1331     return;
   1332   } else if (II == Ident__TIME__) {
   1333     if (!TIMELoc.isValid())
   1334       ComputeDATE_TIME(DATELoc, TIMELoc, *this);
   1335     Tok.setKind(tok::string_literal);
   1336     Tok.setLength(strlen("\"hh:mm:ss\""));
   1337     Tok.setLocation(SourceMgr.createExpansionLoc(TIMELoc, Tok.getLocation(),
   1338                                                  Tok.getLocation(),
   1339                                                  Tok.getLength()));
   1340     return;
   1341   } else if (II == Ident__INCLUDE_LEVEL__) {
   1342     // Compute the presumed include depth of this token.  This can be affected
   1343     // by GNU line markers.
   1344     unsigned Depth = 0;
   1345 
   1346     PresumedLoc PLoc = SourceMgr.getPresumedLoc(Tok.getLocation());
   1347     if (PLoc.isValid()) {
   1348       PLoc = SourceMgr.getPresumedLoc(PLoc.getIncludeLoc());
   1349       for (; PLoc.isValid(); ++Depth)
   1350         PLoc = SourceMgr.getPresumedLoc(PLoc.getIncludeLoc());
   1351     }
   1352 
   1353     // __INCLUDE_LEVEL__ expands to a simple numeric value.
   1354     OS << Depth;
   1355     Tok.setKind(tok::numeric_constant);
   1356   } else if (II == Ident__TIMESTAMP__) {
   1357     // MSVC, ICC, GCC, VisualAge C++ extension.  The generated string should be
   1358     // of the form "Ddd Mmm dd hh::mm::ss yyyy", which is returned by asctime.
   1359 
   1360     // Get the file that we are lexing out of.  If we're currently lexing from
   1361     // a macro, dig into the include stack.
   1362     const FileEntry *CurFile = 0;
   1363     PreprocessorLexer *TheLexer = getCurrentFileLexer();
   1364 
   1365     if (TheLexer)
   1366       CurFile = SourceMgr.getFileEntryForID(TheLexer->getFileID());
   1367 
   1368     const char *Result;
   1369     if (CurFile) {
   1370       time_t TT = CurFile->getModificationTime();
   1371       struct tm *TM = localtime(&TT);
   1372       Result = asctime(TM);
   1373     } else {
   1374       Result = "??? ??? ?? ??:??:?? ????\n";
   1375     }
   1376     // Surround the string with " and strip the trailing newline.
   1377     OS << '"' << StringRef(Result, strlen(Result)-1) << '"';
   1378     Tok.setKind(tok::string_literal);
   1379   } else if (II == Ident__COUNTER__) {
   1380     // __COUNTER__ expands to a simple numeric value.
   1381     OS << CounterValue++;
   1382     Tok.setKind(tok::numeric_constant);
   1383   } else if (II == Ident__has_feature   ||
   1384              II == Ident__has_extension ||
   1385              II == Ident__has_builtin   ||
   1386              II == Ident__has_attribute) {
   1387     // The argument to these builtins should be a parenthesized identifier.
   1388     SourceLocation StartLoc = Tok.getLocation();
   1389 
   1390     bool IsValid = false;
   1391     IdentifierInfo *FeatureII = 0;
   1392 
   1393     // Read the '('.
   1394     LexUnexpandedToken(Tok);
   1395     if (Tok.is(tok::l_paren)) {
   1396       // Read the identifier
   1397       LexUnexpandedToken(Tok);
   1398       if ((FeatureII = Tok.getIdentifierInfo())) {
   1399         // Read the ')'.
   1400         LexUnexpandedToken(Tok);
   1401         if (Tok.is(tok::r_paren))
   1402           IsValid = true;
   1403       }
   1404     }
   1405 
   1406     bool Value = false;
   1407     if (!IsValid)
   1408       Diag(StartLoc, diag::err_feature_check_malformed);
   1409     else if (II == Ident__has_builtin) {
   1410       // Check for a builtin is trivial.
   1411       Value = FeatureII->getBuiltinID() != 0;
   1412     } else if (II == Ident__has_attribute)
   1413       Value = HasAttribute(FeatureII);
   1414     else if (II == Ident__has_extension)
   1415       Value = HasExtension(*this, FeatureII);
   1416     else {
   1417       assert(II == Ident__has_feature && "Must be feature check");
   1418       Value = HasFeature(*this, FeatureII);
   1419     }
   1420 
   1421     OS << (int)Value;
   1422     if (IsValid)
   1423       Tok.setKind(tok::numeric_constant);
   1424   } else if (II == Ident__has_include ||
   1425              II == Ident__has_include_next) {
   1426     // The argument to these two builtins should be a parenthesized
   1427     // file name string literal using angle brackets (<>) or
   1428     // double-quotes ("").
   1429     bool Value;
   1430     if (II == Ident__has_include)
   1431       Value = EvaluateHasInclude(Tok, II, *this);
   1432     else
   1433       Value = EvaluateHasIncludeNext(Tok, II, *this);
   1434     OS << (int)Value;
   1435     if (Tok.is(tok::r_paren))
   1436       Tok.setKind(tok::numeric_constant);
   1437   } else if (II == Ident__has_warning) {
   1438     // The argument should be a parenthesized string literal.
   1439     // The argument to these builtins should be a parenthesized identifier.
   1440     SourceLocation StartLoc = Tok.getLocation();
   1441     bool IsValid = false;
   1442     bool Value = false;
   1443     // Read the '('.
   1444     LexUnexpandedToken(Tok);
   1445     do {
   1446       if (Tok.isNot(tok::l_paren)) {
   1447         Diag(StartLoc, diag::err_warning_check_malformed);
   1448         break;
   1449       }
   1450 
   1451       LexUnexpandedToken(Tok);
   1452       std::string WarningName;
   1453       SourceLocation StrStartLoc = Tok.getLocation();
   1454       if (!FinishLexStringLiteral(Tok, WarningName, "'__has_warning'",
   1455                                   /*MacroExpansion=*/false)) {
   1456         // Eat tokens until ')'.
   1457         while (Tok.isNot(tok::r_paren) && Tok.isNot(tok::eod) &&
   1458                Tok.isNot(tok::eof))
   1459           LexUnexpandedToken(Tok);
   1460         break;
   1461       }
   1462 
   1463       // Is the end a ')'?
   1464       if (!(IsValid = Tok.is(tok::r_paren))) {
   1465         Diag(StartLoc, diag::err_warning_check_malformed);
   1466         break;
   1467       }
   1468 
   1469       if (WarningName.size() < 3 || WarningName[0] != '-' ||
   1470           WarningName[1] != 'W') {
   1471         Diag(StrStartLoc, diag::warn_has_warning_invalid_option);
   1472         break;
   1473       }
   1474 
   1475       // Finally, check if the warning flags maps to a diagnostic group.
   1476       // We construct a SmallVector here to talk to getDiagnosticIDs().
   1477       // Although we don't use the result, this isn't a hot path, and not
   1478       // worth special casing.
   1479       SmallVector<diag::kind, 10> Diags;
   1480       Value = !getDiagnostics().getDiagnosticIDs()->
   1481         getDiagnosticsInGroup(WarningName.substr(2), Diags);
   1482     } while (false);
   1483 
   1484     OS << (int)Value;
   1485     if (IsValid)
   1486       Tok.setKind(tok::numeric_constant);
   1487   } else if (II == Ident__building_module) {
   1488     // The argument to this builtin should be an identifier. The
   1489     // builtin evaluates to 1 when that identifier names the module we are
   1490     // currently building.
   1491     OS << (int)EvaluateBuildingModule(Tok, II, *this);
   1492     Tok.setKind(tok::numeric_constant);
   1493   } else if (II == Ident__MODULE__) {
   1494     // The current module as an identifier.
   1495     OS << getLangOpts().CurrentModule;
   1496     IdentifierInfo *ModuleII = getIdentifierInfo(getLangOpts().CurrentModule);
   1497     Tok.setIdentifierInfo(ModuleII);
   1498     Tok.setKind(ModuleII->getTokenID());
   1499   } else {
   1500     llvm_unreachable("Unknown identifier!");
   1501   }
   1502   CreateString(OS.str(), Tok, Tok.getLocation(), Tok.getLocation());
   1503 }
   1504 
   1505 void Preprocessor::markMacroAsUsed(MacroInfo *MI) {
   1506   // If the 'used' status changed, and the macro requires 'unused' warning,
   1507   // remove its SourceLocation from the warn-for-unused-macro locations.
   1508   if (MI->isWarnIfUnused() && !MI->isUsed())
   1509     WarnUnusedMacroLocs.erase(MI->getDefinitionLoc());
   1510   MI->setIsUsed(true);
   1511 }
   1512