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      1 //===--- PPDirectives.cpp - Directive Handling for Preprocessor -----------===//
      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 # directive processing for the Preprocessor.
     11 //
     12 //===----------------------------------------------------------------------===//
     13 
     14 #include "clang/Lex/Preprocessor.h"
     15 #include "clang/Lex/LiteralSupport.h"
     16 #include "clang/Lex/HeaderSearch.h"
     17 #include "clang/Lex/MacroInfo.h"
     18 #include "clang/Lex/LexDiagnostic.h"
     19 #include "clang/Lex/CodeCompletionHandler.h"
     20 #include "clang/Lex/Pragma.h"
     21 #include "clang/Basic/FileManager.h"
     22 #include "clang/Basic/SourceManager.h"
     23 #include "llvm/ADT/APInt.h"
     24 using namespace clang;
     25 
     26 //===----------------------------------------------------------------------===//
     27 // Utility Methods for Preprocessor Directive Handling.
     28 //===----------------------------------------------------------------------===//
     29 
     30 MacroInfo *Preprocessor::AllocateMacroInfo() {
     31   MacroInfoChain *MIChain;
     32 
     33   if (MICache) {
     34     MIChain = MICache;
     35     MICache = MICache->Next;
     36   }
     37   else {
     38     MIChain = BP.Allocate<MacroInfoChain>();
     39   }
     40 
     41   MIChain->Next = MIChainHead;
     42   MIChain->Prev = 0;
     43   if (MIChainHead)
     44     MIChainHead->Prev = MIChain;
     45   MIChainHead = MIChain;
     46 
     47   return &(MIChain->MI);
     48 }
     49 
     50 MacroInfo *Preprocessor::AllocateMacroInfo(SourceLocation L) {
     51   MacroInfo *MI = AllocateMacroInfo();
     52   new (MI) MacroInfo(L);
     53   return MI;
     54 }
     55 
     56 MacroInfo *Preprocessor::CloneMacroInfo(const MacroInfo &MacroToClone) {
     57   MacroInfo *MI = AllocateMacroInfo();
     58   new (MI) MacroInfo(MacroToClone, BP);
     59   return MI;
     60 }
     61 
     62 /// ReleaseMacroInfo - Release the specified MacroInfo.  This memory will
     63 ///  be reused for allocating new MacroInfo objects.
     64 void Preprocessor::ReleaseMacroInfo(MacroInfo *MI) {
     65   MacroInfoChain *MIChain = (MacroInfoChain*) MI;
     66   if (MacroInfoChain *Prev = MIChain->Prev) {
     67     MacroInfoChain *Next = MIChain->Next;
     68     Prev->Next = Next;
     69     if (Next)
     70       Next->Prev = Prev;
     71   }
     72   else {
     73     assert(MIChainHead == MIChain);
     74     MIChainHead = MIChain->Next;
     75     MIChainHead->Prev = 0;
     76   }
     77   MIChain->Next = MICache;
     78   MICache = MIChain;
     79 
     80   MI->Destroy();
     81 }
     82 
     83 /// DiscardUntilEndOfDirective - Read and discard all tokens remaining on the
     84 /// current line until the tok::eod token is found.
     85 void Preprocessor::DiscardUntilEndOfDirective() {
     86   Token Tmp;
     87   do {
     88     LexUnexpandedToken(Tmp);
     89     assert(Tmp.isNot(tok::eof) && "EOF seen while discarding directive tokens");
     90   } while (Tmp.isNot(tok::eod));
     91 }
     92 
     93 /// ReadMacroName - Lex and validate a macro name, which occurs after a
     94 /// #define or #undef.  This sets the token kind to eod and discards the rest
     95 /// of the macro line if the macro name is invalid.  isDefineUndef is 1 if
     96 /// this is due to a a #define, 2 if #undef directive, 0 if it is something
     97 /// else (e.g. #ifdef).
     98 void Preprocessor::ReadMacroName(Token &MacroNameTok, char isDefineUndef) {
     99   // Read the token, don't allow macro expansion on it.
    100   LexUnexpandedToken(MacroNameTok);
    101 
    102   if (MacroNameTok.is(tok::code_completion)) {
    103     if (CodeComplete)
    104       CodeComplete->CodeCompleteMacroName(isDefineUndef == 1);
    105     LexUnexpandedToken(MacroNameTok);
    106     return;
    107   }
    108 
    109   // Missing macro name?
    110   if (MacroNameTok.is(tok::eod)) {
    111     Diag(MacroNameTok, diag::err_pp_missing_macro_name);
    112     return;
    113   }
    114 
    115   IdentifierInfo *II = MacroNameTok.getIdentifierInfo();
    116   if (II == 0) {
    117     bool Invalid = false;
    118     std::string Spelling = getSpelling(MacroNameTok, &Invalid);
    119     if (Invalid)
    120       return;
    121 
    122     const IdentifierInfo &Info = Identifiers.get(Spelling);
    123     if (Info.isCPlusPlusOperatorKeyword())
    124       // C++ 2.5p2: Alternative tokens behave the same as its primary token
    125       // except for their spellings.
    126       Diag(MacroNameTok, diag::err_pp_operator_used_as_macro_name) << Spelling;
    127     else
    128       Diag(MacroNameTok, diag::err_pp_macro_not_identifier);
    129     // Fall through on error.
    130   } else if (isDefineUndef && II->getPPKeywordID() == tok::pp_defined) {
    131     // Error if defining "defined": C99 6.10.8.4.
    132     Diag(MacroNameTok, diag::err_defined_macro_name);
    133   } else if (isDefineUndef && II->hasMacroDefinition() &&
    134              getMacroInfo(II)->isBuiltinMacro()) {
    135     // Error if defining "__LINE__" and other builtins: C99 6.10.8.4.
    136     if (isDefineUndef == 1)
    137       Diag(MacroNameTok, diag::pp_redef_builtin_macro);
    138     else
    139       Diag(MacroNameTok, diag::pp_undef_builtin_macro);
    140   } else {
    141     // Okay, we got a good identifier node.  Return it.
    142     return;
    143   }
    144 
    145   // Invalid macro name, read and discard the rest of the line.  Then set the
    146   // token kind to tok::eod.
    147   MacroNameTok.setKind(tok::eod);
    148   return DiscardUntilEndOfDirective();
    149 }
    150 
    151 /// CheckEndOfDirective - Ensure that the next token is a tok::eod token.  If
    152 /// not, emit a diagnostic and consume up until the eod.  If EnableMacros is
    153 /// true, then we consider macros that expand to zero tokens as being ok.
    154 void Preprocessor::CheckEndOfDirective(const char *DirType, bool EnableMacros) {
    155   Token Tmp;
    156   // Lex unexpanded tokens for most directives: macros might expand to zero
    157   // tokens, causing us to miss diagnosing invalid lines.  Some directives (like
    158   // #line) allow empty macros.
    159   if (EnableMacros)
    160     Lex(Tmp);
    161   else
    162     LexUnexpandedToken(Tmp);
    163 
    164   // There should be no tokens after the directive, but we allow them as an
    165   // extension.
    166   while (Tmp.is(tok::comment))  // Skip comments in -C mode.
    167     LexUnexpandedToken(Tmp);
    168 
    169   if (Tmp.isNot(tok::eod)) {
    170     // Add a fixit in GNU/C99/C++ mode.  Don't offer a fixit for strict-C89,
    171     // or if this is a macro-style preprocessing directive, because it is more
    172     // trouble than it is worth to insert /**/ and check that there is no /**/
    173     // in the range also.
    174     FixItHint Hint;
    175     if ((Features.GNUMode || Features.C99 || Features.CPlusPlus) &&
    176         !CurTokenLexer)
    177       Hint = FixItHint::CreateInsertion(Tmp.getLocation(),"//");
    178     Diag(Tmp, diag::ext_pp_extra_tokens_at_eol) << DirType << Hint;
    179     DiscardUntilEndOfDirective();
    180   }
    181 }
    182 
    183 
    184 
    185 /// SkipExcludedConditionalBlock - We just read a #if or related directive and
    186 /// decided that the subsequent tokens are in the #if'd out portion of the
    187 /// file.  Lex the rest of the file, until we see an #endif.  If
    188 /// FoundNonSkipPortion is true, then we have already emitted code for part of
    189 /// this #if directive, so #else/#elif blocks should never be entered. If ElseOk
    190 /// is true, then #else directives are ok, if not, then we have already seen one
    191 /// so a #else directive is a duplicate.  When this returns, the caller can lex
    192 /// the first valid token.
    193 void Preprocessor::SkipExcludedConditionalBlock(SourceLocation IfTokenLoc,
    194                                                 bool FoundNonSkipPortion,
    195                                                 bool FoundElse) {
    196   ++NumSkipped;
    197   assert(CurTokenLexer == 0 && CurPPLexer && "Lexing a macro, not a file?");
    198 
    199   CurPPLexer->pushConditionalLevel(IfTokenLoc, /*isSkipping*/false,
    200                                  FoundNonSkipPortion, FoundElse);
    201 
    202   if (CurPTHLexer) {
    203     PTHSkipExcludedConditionalBlock();
    204     return;
    205   }
    206 
    207   // Enter raw mode to disable identifier lookup (and thus macro expansion),
    208   // disabling warnings, etc.
    209   CurPPLexer->LexingRawMode = true;
    210   Token Tok;
    211   while (1) {
    212     CurLexer->Lex(Tok);
    213 
    214     if (Tok.is(tok::code_completion)) {
    215       if (CodeComplete)
    216         CodeComplete->CodeCompleteInConditionalExclusion();
    217       continue;
    218     }
    219 
    220     // If this is the end of the buffer, we have an error.
    221     if (Tok.is(tok::eof)) {
    222       // Emit errors for each unterminated conditional on the stack, including
    223       // the current one.
    224       while (!CurPPLexer->ConditionalStack.empty()) {
    225         if (!isCodeCompletionFile(Tok.getLocation()))
    226           Diag(CurPPLexer->ConditionalStack.back().IfLoc,
    227                diag::err_pp_unterminated_conditional);
    228         CurPPLexer->ConditionalStack.pop_back();
    229       }
    230 
    231       // Just return and let the caller lex after this #include.
    232       break;
    233     }
    234 
    235     // If this token is not a preprocessor directive, just skip it.
    236     if (Tok.isNot(tok::hash) || !Tok.isAtStartOfLine())
    237       continue;
    238 
    239     // We just parsed a # character at the start of a line, so we're in
    240     // directive mode.  Tell the lexer this so any newlines we see will be
    241     // converted into an EOD token (this terminates the macro).
    242     CurPPLexer->ParsingPreprocessorDirective = true;
    243     if (CurLexer) CurLexer->SetCommentRetentionState(false);
    244 
    245 
    246     // Read the next token, the directive flavor.
    247     LexUnexpandedToken(Tok);
    248 
    249     // If this isn't an identifier directive (e.g. is "# 1\n" or "#\n", or
    250     // something bogus), skip it.
    251     if (Tok.isNot(tok::raw_identifier)) {
    252       CurPPLexer->ParsingPreprocessorDirective = false;
    253       // Restore comment saving mode.
    254       if (CurLexer) CurLexer->SetCommentRetentionState(KeepComments);
    255       continue;
    256     }
    257 
    258     // If the first letter isn't i or e, it isn't intesting to us.  We know that
    259     // this is safe in the face of spelling differences, because there is no way
    260     // to spell an i/e in a strange way that is another letter.  Skipping this
    261     // allows us to avoid looking up the identifier info for #define/#undef and
    262     // other common directives.
    263     const char *RawCharData = Tok.getRawIdentifierData();
    264 
    265     char FirstChar = RawCharData[0];
    266     if (FirstChar >= 'a' && FirstChar <= 'z' &&
    267         FirstChar != 'i' && FirstChar != 'e') {
    268       CurPPLexer->ParsingPreprocessorDirective = false;
    269       // Restore comment saving mode.
    270       if (CurLexer) CurLexer->SetCommentRetentionState(KeepComments);
    271       continue;
    272     }
    273 
    274     // Get the identifier name without trigraphs or embedded newlines.  Note
    275     // that we can't use Tok.getIdentifierInfo() because its lookup is disabled
    276     // when skipping.
    277     char DirectiveBuf[20];
    278     llvm::StringRef Directive;
    279     if (!Tok.needsCleaning() && Tok.getLength() < 20) {
    280       Directive = llvm::StringRef(RawCharData, Tok.getLength());
    281     } else {
    282       std::string DirectiveStr = getSpelling(Tok);
    283       unsigned IdLen = DirectiveStr.size();
    284       if (IdLen >= 20) {
    285         CurPPLexer->ParsingPreprocessorDirective = false;
    286         // Restore comment saving mode.
    287         if (CurLexer) CurLexer->SetCommentRetentionState(KeepComments);
    288         continue;
    289       }
    290       memcpy(DirectiveBuf, &DirectiveStr[0], IdLen);
    291       Directive = llvm::StringRef(DirectiveBuf, IdLen);
    292     }
    293 
    294     if (Directive.startswith("if")) {
    295       llvm::StringRef Sub = Directive.substr(2);
    296       if (Sub.empty() ||   // "if"
    297           Sub == "def" ||   // "ifdef"
    298           Sub == "ndef") {  // "ifndef"
    299         // We know the entire #if/#ifdef/#ifndef block will be skipped, don't
    300         // bother parsing the condition.
    301         DiscardUntilEndOfDirective();
    302         CurPPLexer->pushConditionalLevel(Tok.getLocation(), /*wasskipping*/true,
    303                                        /*foundnonskip*/false,
    304                                        /*foundelse*/false);
    305 
    306         if (Callbacks)
    307           Callbacks->Endif();
    308       }
    309     } else if (Directive[0] == 'e') {
    310       llvm::StringRef Sub = Directive.substr(1);
    311       if (Sub == "ndif") {  // "endif"
    312         CheckEndOfDirective("endif");
    313         PPConditionalInfo CondInfo;
    314         CondInfo.WasSkipping = true; // Silence bogus warning.
    315         bool InCond = CurPPLexer->popConditionalLevel(CondInfo);
    316         (void)InCond;  // Silence warning in no-asserts mode.
    317         assert(!InCond && "Can't be skipping if not in a conditional!");
    318 
    319         // If we popped the outermost skipping block, we're done skipping!
    320         if (!CondInfo.WasSkipping)
    321           break;
    322       } else if (Sub == "lse") { // "else".
    323         // #else directive in a skipping conditional.  If not in some other
    324         // skipping conditional, and if #else hasn't already been seen, enter it
    325         // as a non-skipping conditional.
    326         PPConditionalInfo &CondInfo = CurPPLexer->peekConditionalLevel();
    327 
    328         // If this is a #else with a #else before it, report the error.
    329         if (CondInfo.FoundElse) Diag(Tok, diag::pp_err_else_after_else);
    330 
    331         // Note that we've seen a #else in this conditional.
    332         CondInfo.FoundElse = true;
    333 
    334         if (Callbacks)
    335           Callbacks->Else();
    336 
    337         // If the conditional is at the top level, and the #if block wasn't
    338         // entered, enter the #else block now.
    339         if (!CondInfo.WasSkipping && !CondInfo.FoundNonSkip) {
    340           CondInfo.FoundNonSkip = true;
    341           CheckEndOfDirective("else");
    342           break;
    343         } else {
    344           DiscardUntilEndOfDirective();  // C99 6.10p4.
    345         }
    346       } else if (Sub == "lif") {  // "elif".
    347         PPConditionalInfo &CondInfo = CurPPLexer->peekConditionalLevel();
    348 
    349         bool ShouldEnter;
    350         const SourceLocation ConditionalBegin = CurPPLexer->getSourceLocation();
    351         // If this is in a skipping block or if we're already handled this #if
    352         // block, don't bother parsing the condition.
    353         if (CondInfo.WasSkipping || CondInfo.FoundNonSkip) {
    354           DiscardUntilEndOfDirective();
    355           ShouldEnter = false;
    356         } else {
    357           // Restore the value of LexingRawMode so that identifiers are
    358           // looked up, etc, inside the #elif expression.
    359           assert(CurPPLexer->LexingRawMode && "We have to be skipping here!");
    360           CurPPLexer->LexingRawMode = false;
    361           IdentifierInfo *IfNDefMacro = 0;
    362           ShouldEnter = EvaluateDirectiveExpression(IfNDefMacro);
    363           CurPPLexer->LexingRawMode = true;
    364         }
    365         const SourceLocation ConditionalEnd = CurPPLexer->getSourceLocation();
    366 
    367         // If this is a #elif with a #else before it, report the error.
    368         if (CondInfo.FoundElse) Diag(Tok, diag::pp_err_elif_after_else);
    369 
    370         if (Callbacks)
    371           Callbacks->Elif(SourceRange(ConditionalBegin, ConditionalEnd));
    372 
    373         // If this condition is true, enter it!
    374         if (ShouldEnter) {
    375           CondInfo.FoundNonSkip = true;
    376           break;
    377         }
    378       }
    379     }
    380 
    381     CurPPLexer->ParsingPreprocessorDirective = false;
    382     // Restore comment saving mode.
    383     if (CurLexer) CurLexer->SetCommentRetentionState(KeepComments);
    384   }
    385 
    386   // Finally, if we are out of the conditional (saw an #endif or ran off the end
    387   // of the file, just stop skipping and return to lexing whatever came after
    388   // the #if block.
    389   CurPPLexer->LexingRawMode = false;
    390 }
    391 
    392 void Preprocessor::PTHSkipExcludedConditionalBlock() {
    393 
    394   while (1) {
    395     assert(CurPTHLexer);
    396     assert(CurPTHLexer->LexingRawMode == false);
    397 
    398     // Skip to the next '#else', '#elif', or #endif.
    399     if (CurPTHLexer->SkipBlock()) {
    400       // We have reached an #endif.  Both the '#' and 'endif' tokens
    401       // have been consumed by the PTHLexer.  Just pop off the condition level.
    402       PPConditionalInfo CondInfo;
    403       bool InCond = CurPTHLexer->popConditionalLevel(CondInfo);
    404       (void)InCond;  // Silence warning in no-asserts mode.
    405       assert(!InCond && "Can't be skipping if not in a conditional!");
    406       break;
    407     }
    408 
    409     // We have reached a '#else' or '#elif'.  Lex the next token to get
    410     // the directive flavor.
    411     Token Tok;
    412     LexUnexpandedToken(Tok);
    413 
    414     // We can actually look up the IdentifierInfo here since we aren't in
    415     // raw mode.
    416     tok::PPKeywordKind K = Tok.getIdentifierInfo()->getPPKeywordID();
    417 
    418     if (K == tok::pp_else) {
    419       // #else: Enter the else condition.  We aren't in a nested condition
    420       //  since we skip those. We're always in the one matching the last
    421       //  blocked we skipped.
    422       PPConditionalInfo &CondInfo = CurPTHLexer->peekConditionalLevel();
    423       // Note that we've seen a #else in this conditional.
    424       CondInfo.FoundElse = true;
    425 
    426       // If the #if block wasn't entered then enter the #else block now.
    427       if (!CondInfo.FoundNonSkip) {
    428         CondInfo.FoundNonSkip = true;
    429 
    430         // Scan until the eod token.
    431         CurPTHLexer->ParsingPreprocessorDirective = true;
    432         DiscardUntilEndOfDirective();
    433         CurPTHLexer->ParsingPreprocessorDirective = false;
    434 
    435         break;
    436       }
    437 
    438       // Otherwise skip this block.
    439       continue;
    440     }
    441 
    442     assert(K == tok::pp_elif);
    443     PPConditionalInfo &CondInfo = CurPTHLexer->peekConditionalLevel();
    444 
    445     // If this is a #elif with a #else before it, report the error.
    446     if (CondInfo.FoundElse)
    447       Diag(Tok, diag::pp_err_elif_after_else);
    448 
    449     // If this is in a skipping block or if we're already handled this #if
    450     // block, don't bother parsing the condition.  We just skip this block.
    451     if (CondInfo.FoundNonSkip)
    452       continue;
    453 
    454     // Evaluate the condition of the #elif.
    455     IdentifierInfo *IfNDefMacro = 0;
    456     CurPTHLexer->ParsingPreprocessorDirective = true;
    457     bool ShouldEnter = EvaluateDirectiveExpression(IfNDefMacro);
    458     CurPTHLexer->ParsingPreprocessorDirective = false;
    459 
    460     // If this condition is true, enter it!
    461     if (ShouldEnter) {
    462       CondInfo.FoundNonSkip = true;
    463       break;
    464     }
    465 
    466     // Otherwise, skip this block and go to the next one.
    467     continue;
    468   }
    469 }
    470 
    471 /// LookupFile - Given a "foo" or <foo> reference, look up the indicated file,
    472 /// return null on failure.  isAngled indicates whether the file reference is
    473 /// for system #include's or not (i.e. using <> instead of "").
    474 const FileEntry *Preprocessor::LookupFile(
    475     llvm::StringRef Filename,
    476     bool isAngled,
    477     const DirectoryLookup *FromDir,
    478     const DirectoryLookup *&CurDir,
    479     llvm::SmallVectorImpl<char> *SearchPath,
    480     llvm::SmallVectorImpl<char> *RelativePath) {
    481   // If the header lookup mechanism may be relative to the current file, pass in
    482   // info about where the current file is.
    483   const FileEntry *CurFileEnt = 0;
    484   if (!FromDir) {
    485     FileID FID = getCurrentFileLexer()->getFileID();
    486     CurFileEnt = SourceMgr.getFileEntryForID(FID);
    487 
    488     // If there is no file entry associated with this file, it must be the
    489     // predefines buffer.  Any other file is not lexed with a normal lexer, so
    490     // it won't be scanned for preprocessor directives.   If we have the
    491     // predefines buffer, resolve #include references (which come from the
    492     // -include command line argument) as if they came from the main file, this
    493     // affects file lookup etc.
    494     if (CurFileEnt == 0) {
    495       FID = SourceMgr.getMainFileID();
    496       CurFileEnt = SourceMgr.getFileEntryForID(FID);
    497     }
    498   }
    499 
    500   // Do a standard file entry lookup.
    501   CurDir = CurDirLookup;
    502   const FileEntry *FE = HeaderInfo.LookupFile(
    503       Filename, isAngled, FromDir, CurDir, CurFileEnt,
    504       SearchPath, RelativePath);
    505   if (FE) return FE;
    506 
    507   // Otherwise, see if this is a subframework header.  If so, this is relative
    508   // to one of the headers on the #include stack.  Walk the list of the current
    509   // headers on the #include stack and pass them to HeaderInfo.
    510   if (IsFileLexer()) {
    511     if ((CurFileEnt = SourceMgr.getFileEntryForID(CurPPLexer->getFileID())))
    512       if ((FE = HeaderInfo.LookupSubframeworkHeader(Filename, CurFileEnt,
    513                                                     SearchPath, RelativePath)))
    514         return FE;
    515   }
    516 
    517   for (unsigned i = 0, e = IncludeMacroStack.size(); i != e; ++i) {
    518     IncludeStackInfo &ISEntry = IncludeMacroStack[e-i-1];
    519     if (IsFileLexer(ISEntry)) {
    520       if ((CurFileEnt =
    521            SourceMgr.getFileEntryForID(ISEntry.ThePPLexer->getFileID())))
    522         if ((FE = HeaderInfo.LookupSubframeworkHeader(
    523                 Filename, CurFileEnt, SearchPath, RelativePath)))
    524           return FE;
    525     }
    526   }
    527 
    528   // Otherwise, we really couldn't find the file.
    529   return 0;
    530 }
    531 
    532 
    533 //===----------------------------------------------------------------------===//
    534 // Preprocessor Directive Handling.
    535 //===----------------------------------------------------------------------===//
    536 
    537 /// HandleDirective - This callback is invoked when the lexer sees a # token
    538 /// at the start of a line.  This consumes the directive, modifies the
    539 /// lexer/preprocessor state, and advances the lexer(s) so that the next token
    540 /// read is the correct one.
    541 void Preprocessor::HandleDirective(Token &Result) {
    542   // FIXME: Traditional: # with whitespace before it not recognized by K&R?
    543 
    544   // We just parsed a # character at the start of a line, so we're in directive
    545   // mode.  Tell the lexer this so any newlines we see will be converted into an
    546   // EOD token (which terminates the directive).
    547   CurPPLexer->ParsingPreprocessorDirective = true;
    548 
    549   ++NumDirectives;
    550 
    551   // We are about to read a token.  For the multiple-include optimization FA to
    552   // work, we have to remember if we had read any tokens *before* this
    553   // pp-directive.
    554   bool ReadAnyTokensBeforeDirective =CurPPLexer->MIOpt.getHasReadAnyTokensVal();
    555 
    556   // Save the '#' token in case we need to return it later.
    557   Token SavedHash = Result;
    558 
    559   // Read the next token, the directive flavor.  This isn't expanded due to
    560   // C99 6.10.3p8.
    561   LexUnexpandedToken(Result);
    562 
    563   // C99 6.10.3p11: Is this preprocessor directive in macro invocation?  e.g.:
    564   //   #define A(x) #x
    565   //   A(abc
    566   //     #warning blah
    567   //   def)
    568   // If so, the user is relying on non-portable behavior, emit a diagnostic.
    569   if (InMacroArgs)
    570     Diag(Result, diag::ext_embedded_directive);
    571 
    572 TryAgain:
    573   switch (Result.getKind()) {
    574   case tok::eod:
    575     return;   // null directive.
    576   case tok::comment:
    577     // Handle stuff like "# /*foo*/ define X" in -E -C mode.
    578     LexUnexpandedToken(Result);
    579     goto TryAgain;
    580   case tok::code_completion:
    581     if (CodeComplete)
    582       CodeComplete->CodeCompleteDirective(
    583                                     CurPPLexer->getConditionalStackDepth() > 0);
    584     return;
    585   case tok::numeric_constant:  // # 7  GNU line marker directive.
    586     if (getLangOptions().AsmPreprocessor)
    587       break;  // # 4 is not a preprocessor directive in .S files.
    588     return HandleDigitDirective(Result);
    589   default:
    590     IdentifierInfo *II = Result.getIdentifierInfo();
    591     if (II == 0) break;  // Not an identifier.
    592 
    593     // Ask what the preprocessor keyword ID is.
    594     switch (II->getPPKeywordID()) {
    595     default: break;
    596     // C99 6.10.1 - Conditional Inclusion.
    597     case tok::pp_if:
    598       return HandleIfDirective(Result, ReadAnyTokensBeforeDirective);
    599     case tok::pp_ifdef:
    600       return HandleIfdefDirective(Result, false, true/*not valid for miopt*/);
    601     case tok::pp_ifndef:
    602       return HandleIfdefDirective(Result, true, ReadAnyTokensBeforeDirective);
    603     case tok::pp_elif:
    604       return HandleElifDirective(Result);
    605     case tok::pp_else:
    606       return HandleElseDirective(Result);
    607     case tok::pp_endif:
    608       return HandleEndifDirective(Result);
    609 
    610     // C99 6.10.2 - Source File Inclusion.
    611     case tok::pp_include:
    612       // Handle #include.
    613       return HandleIncludeDirective(SavedHash.getLocation(), Result);
    614     case tok::pp___include_macros:
    615       // Handle -imacros.
    616       return HandleIncludeMacrosDirective(SavedHash.getLocation(), Result);
    617 
    618     // C99 6.10.3 - Macro Replacement.
    619     case tok::pp_define:
    620       return HandleDefineDirective(Result);
    621     case tok::pp_undef:
    622       return HandleUndefDirective(Result);
    623 
    624     // C99 6.10.4 - Line Control.
    625     case tok::pp_line:
    626       return HandleLineDirective(Result);
    627 
    628     // C99 6.10.5 - Error Directive.
    629     case tok::pp_error:
    630       return HandleUserDiagnosticDirective(Result, false);
    631 
    632     // C99 6.10.6 - Pragma Directive.
    633     case tok::pp_pragma:
    634       return HandlePragmaDirective(PIK_HashPragma);
    635 
    636     // GNU Extensions.
    637     case tok::pp_import:
    638       return HandleImportDirective(SavedHash.getLocation(), Result);
    639     case tok::pp_include_next:
    640       return HandleIncludeNextDirective(SavedHash.getLocation(), Result);
    641 
    642     case tok::pp_warning:
    643       Diag(Result, diag::ext_pp_warning_directive);
    644       return HandleUserDiagnosticDirective(Result, true);
    645     case tok::pp_ident:
    646       return HandleIdentSCCSDirective(Result);
    647     case tok::pp_sccs:
    648       return HandleIdentSCCSDirective(Result);
    649     case tok::pp_assert:
    650       //isExtension = true;  // FIXME: implement #assert
    651       break;
    652     case tok::pp_unassert:
    653       //isExtension = true;  // FIXME: implement #unassert
    654       break;
    655     }
    656     break;
    657   }
    658 
    659   // If this is a .S file, treat unknown # directives as non-preprocessor
    660   // directives.  This is important because # may be a comment or introduce
    661   // various pseudo-ops.  Just return the # token and push back the following
    662   // token to be lexed next time.
    663   if (getLangOptions().AsmPreprocessor) {
    664     Token *Toks = new Token[2];
    665     // Return the # and the token after it.
    666     Toks[0] = SavedHash;
    667     Toks[1] = Result;
    668 
    669     // If the second token is a hashhash token, then we need to translate it to
    670     // unknown so the token lexer doesn't try to perform token pasting.
    671     if (Result.is(tok::hashhash))
    672       Toks[1].setKind(tok::unknown);
    673 
    674     // Enter this token stream so that we re-lex the tokens.  Make sure to
    675     // enable macro expansion, in case the token after the # is an identifier
    676     // that is expanded.
    677     EnterTokenStream(Toks, 2, false, true);
    678     return;
    679   }
    680 
    681   // If we reached here, the preprocessing token is not valid!
    682   Diag(Result, diag::err_pp_invalid_directive);
    683 
    684   // Read the rest of the PP line.
    685   DiscardUntilEndOfDirective();
    686 
    687   // Okay, we're done parsing the directive.
    688 }
    689 
    690 /// GetLineValue - Convert a numeric token into an unsigned value, emitting
    691 /// Diagnostic DiagID if it is invalid, and returning the value in Val.
    692 static bool GetLineValue(Token &DigitTok, unsigned &Val,
    693                          unsigned DiagID, Preprocessor &PP) {
    694   if (DigitTok.isNot(tok::numeric_constant)) {
    695     PP.Diag(DigitTok, DiagID);
    696 
    697     if (DigitTok.isNot(tok::eod))
    698       PP.DiscardUntilEndOfDirective();
    699     return true;
    700   }
    701 
    702   llvm::SmallString<64> IntegerBuffer;
    703   IntegerBuffer.resize(DigitTok.getLength());
    704   const char *DigitTokBegin = &IntegerBuffer[0];
    705   bool Invalid = false;
    706   unsigned ActualLength = PP.getSpelling(DigitTok, DigitTokBegin, &Invalid);
    707   if (Invalid)
    708     return true;
    709 
    710   // Verify that we have a simple digit-sequence, and compute the value.  This
    711   // is always a simple digit string computed in decimal, so we do this manually
    712   // here.
    713   Val = 0;
    714   for (unsigned i = 0; i != ActualLength; ++i) {
    715     if (!isdigit(DigitTokBegin[i])) {
    716       PP.Diag(PP.AdvanceToTokenCharacter(DigitTok.getLocation(), i),
    717               diag::err_pp_line_digit_sequence);
    718       PP.DiscardUntilEndOfDirective();
    719       return true;
    720     }
    721 
    722     unsigned NextVal = Val*10+(DigitTokBegin[i]-'0');
    723     if (NextVal < Val) { // overflow.
    724       PP.Diag(DigitTok, DiagID);
    725       PP.DiscardUntilEndOfDirective();
    726       return true;
    727     }
    728     Val = NextVal;
    729   }
    730 
    731   // Reject 0, this is needed both by #line numbers and flags.
    732   if (Val == 0) {
    733     PP.Diag(DigitTok, DiagID);
    734     PP.DiscardUntilEndOfDirective();
    735     return true;
    736   }
    737 
    738   if (DigitTokBegin[0] == '0')
    739     PP.Diag(DigitTok.getLocation(), diag::warn_pp_line_decimal);
    740 
    741   return false;
    742 }
    743 
    744 /// HandleLineDirective - Handle #line directive: C99 6.10.4.  The two
    745 /// acceptable forms are:
    746 ///   # line digit-sequence
    747 ///   # line digit-sequence "s-char-sequence"
    748 void Preprocessor::HandleLineDirective(Token &Tok) {
    749   // Read the line # and string argument.  Per C99 6.10.4p5, these tokens are
    750   // expanded.
    751   Token DigitTok;
    752   Lex(DigitTok);
    753 
    754   // Validate the number and convert it to an unsigned.
    755   unsigned LineNo;
    756   if (GetLineValue(DigitTok, LineNo, diag::err_pp_line_requires_integer,*this))
    757     return;
    758 
    759   // Enforce C99 6.10.4p3: "The digit sequence shall not specify ... a
    760   // number greater than 2147483647".  C90 requires that the line # be <= 32767.
    761   unsigned LineLimit = Features.C99 ? 2147483648U : 32768U;
    762   if (LineNo >= LineLimit)
    763     Diag(DigitTok, diag::ext_pp_line_too_big) << LineLimit;
    764 
    765   int FilenameID = -1;
    766   Token StrTok;
    767   Lex(StrTok);
    768 
    769   // If the StrTok is "eod", then it wasn't present.  Otherwise, it must be a
    770   // string followed by eod.
    771   if (StrTok.is(tok::eod))
    772     ; // ok
    773   else if (StrTok.isNot(tok::string_literal)) {
    774     Diag(StrTok, diag::err_pp_line_invalid_filename);
    775     DiscardUntilEndOfDirective();
    776     return;
    777   } else {
    778     // Parse and validate the string, converting it into a unique ID.
    779     StringLiteralParser Literal(&StrTok, 1, *this);
    780     assert(!Literal.AnyWide && "Didn't allow wide strings in");
    781     if (Literal.hadError)
    782       return DiscardUntilEndOfDirective();
    783     if (Literal.Pascal) {
    784       Diag(StrTok, diag::err_pp_linemarker_invalid_filename);
    785       return DiscardUntilEndOfDirective();
    786     }
    787     FilenameID = SourceMgr.getLineTableFilenameID(Literal.GetString());
    788 
    789     // Verify that there is nothing after the string, other than EOD.  Because
    790     // of C99 6.10.4p5, macros that expand to empty tokens are ok.
    791     CheckEndOfDirective("line", true);
    792   }
    793 
    794   SourceMgr.AddLineNote(DigitTok.getLocation(), LineNo, FilenameID);
    795 
    796   if (Callbacks)
    797     Callbacks->FileChanged(CurPPLexer->getSourceLocation(),
    798                            PPCallbacks::RenameFile,
    799                            SrcMgr::C_User);
    800 }
    801 
    802 /// ReadLineMarkerFlags - Parse and validate any flags at the end of a GNU line
    803 /// marker directive.
    804 static bool ReadLineMarkerFlags(bool &IsFileEntry, bool &IsFileExit,
    805                                 bool &IsSystemHeader, bool &IsExternCHeader,
    806                                 Preprocessor &PP) {
    807   unsigned FlagVal;
    808   Token FlagTok;
    809   PP.Lex(FlagTok);
    810   if (FlagTok.is(tok::eod)) return false;
    811   if (GetLineValue(FlagTok, FlagVal, diag::err_pp_linemarker_invalid_flag, PP))
    812     return true;
    813 
    814   if (FlagVal == 1) {
    815     IsFileEntry = true;
    816 
    817     PP.Lex(FlagTok);
    818     if (FlagTok.is(tok::eod)) return false;
    819     if (GetLineValue(FlagTok, FlagVal, diag::err_pp_linemarker_invalid_flag,PP))
    820       return true;
    821   } else if (FlagVal == 2) {
    822     IsFileExit = true;
    823 
    824     SourceManager &SM = PP.getSourceManager();
    825     // If we are leaving the current presumed file, check to make sure the
    826     // presumed include stack isn't empty!
    827     FileID CurFileID =
    828       SM.getDecomposedInstantiationLoc(FlagTok.getLocation()).first;
    829     PresumedLoc PLoc = SM.getPresumedLoc(FlagTok.getLocation());
    830     if (PLoc.isInvalid())
    831       return true;
    832 
    833     // If there is no include loc (main file) or if the include loc is in a
    834     // different physical file, then we aren't in a "1" line marker flag region.
    835     SourceLocation IncLoc = PLoc.getIncludeLoc();
    836     if (IncLoc.isInvalid() ||
    837         SM.getDecomposedInstantiationLoc(IncLoc).first != CurFileID) {
    838       PP.Diag(FlagTok, diag::err_pp_linemarker_invalid_pop);
    839       PP.DiscardUntilEndOfDirective();
    840       return true;
    841     }
    842 
    843     PP.Lex(FlagTok);
    844     if (FlagTok.is(tok::eod)) return false;
    845     if (GetLineValue(FlagTok, FlagVal, diag::err_pp_linemarker_invalid_flag,PP))
    846       return true;
    847   }
    848 
    849   // We must have 3 if there are still flags.
    850   if (FlagVal != 3) {
    851     PP.Diag(FlagTok, diag::err_pp_linemarker_invalid_flag);
    852     PP.DiscardUntilEndOfDirective();
    853     return true;
    854   }
    855 
    856   IsSystemHeader = true;
    857 
    858   PP.Lex(FlagTok);
    859   if (FlagTok.is(tok::eod)) return false;
    860   if (GetLineValue(FlagTok, FlagVal, diag::err_pp_linemarker_invalid_flag, PP))
    861     return true;
    862 
    863   // We must have 4 if there is yet another flag.
    864   if (FlagVal != 4) {
    865     PP.Diag(FlagTok, diag::err_pp_linemarker_invalid_flag);
    866     PP.DiscardUntilEndOfDirective();
    867     return true;
    868   }
    869 
    870   IsExternCHeader = true;
    871 
    872   PP.Lex(FlagTok);
    873   if (FlagTok.is(tok::eod)) return false;
    874 
    875   // There are no more valid flags here.
    876   PP.Diag(FlagTok, diag::err_pp_linemarker_invalid_flag);
    877   PP.DiscardUntilEndOfDirective();
    878   return true;
    879 }
    880 
    881 /// HandleDigitDirective - Handle a GNU line marker directive, whose syntax is
    882 /// one of the following forms:
    883 ///
    884 ///     # 42
    885 ///     # 42 "file" ('1' | '2')?
    886 ///     # 42 "file" ('1' | '2')? '3' '4'?
    887 ///
    888 void Preprocessor::HandleDigitDirective(Token &DigitTok) {
    889   // Validate the number and convert it to an unsigned.  GNU does not have a
    890   // line # limit other than it fit in 32-bits.
    891   unsigned LineNo;
    892   if (GetLineValue(DigitTok, LineNo, diag::err_pp_linemarker_requires_integer,
    893                    *this))
    894     return;
    895 
    896   Token StrTok;
    897   Lex(StrTok);
    898 
    899   bool IsFileEntry = false, IsFileExit = false;
    900   bool IsSystemHeader = false, IsExternCHeader = false;
    901   int FilenameID = -1;
    902 
    903   // If the StrTok is "eod", then it wasn't present.  Otherwise, it must be a
    904   // string followed by eod.
    905   if (StrTok.is(tok::eod))
    906     ; // ok
    907   else if (StrTok.isNot(tok::string_literal)) {
    908     Diag(StrTok, diag::err_pp_linemarker_invalid_filename);
    909     return DiscardUntilEndOfDirective();
    910   } else {
    911     // Parse and validate the string, converting it into a unique ID.
    912     StringLiteralParser Literal(&StrTok, 1, *this);
    913     assert(!Literal.AnyWide && "Didn't allow wide strings in");
    914     if (Literal.hadError)
    915       return DiscardUntilEndOfDirective();
    916     if (Literal.Pascal) {
    917       Diag(StrTok, diag::err_pp_linemarker_invalid_filename);
    918       return DiscardUntilEndOfDirective();
    919     }
    920     FilenameID = SourceMgr.getLineTableFilenameID(Literal.GetString());
    921 
    922     // If a filename was present, read any flags that are present.
    923     if (ReadLineMarkerFlags(IsFileEntry, IsFileExit,
    924                             IsSystemHeader, IsExternCHeader, *this))
    925       return;
    926   }
    927 
    928   // Create a line note with this information.
    929   SourceMgr.AddLineNote(DigitTok.getLocation(), LineNo, FilenameID,
    930                         IsFileEntry, IsFileExit,
    931                         IsSystemHeader, IsExternCHeader);
    932 
    933   // If the preprocessor has callbacks installed, notify them of the #line
    934   // change.  This is used so that the line marker comes out in -E mode for
    935   // example.
    936   if (Callbacks) {
    937     PPCallbacks::FileChangeReason Reason = PPCallbacks::RenameFile;
    938     if (IsFileEntry)
    939       Reason = PPCallbacks::EnterFile;
    940     else if (IsFileExit)
    941       Reason = PPCallbacks::ExitFile;
    942     SrcMgr::CharacteristicKind FileKind = SrcMgr::C_User;
    943     if (IsExternCHeader)
    944       FileKind = SrcMgr::C_ExternCSystem;
    945     else if (IsSystemHeader)
    946       FileKind = SrcMgr::C_System;
    947 
    948     Callbacks->FileChanged(CurPPLexer->getSourceLocation(), Reason, FileKind);
    949   }
    950 }
    951 
    952 
    953 /// HandleUserDiagnosticDirective - Handle a #warning or #error directive.
    954 ///
    955 void Preprocessor::HandleUserDiagnosticDirective(Token &Tok,
    956                                                  bool isWarning) {
    957   // PTH doesn't emit #warning or #error directives.
    958   if (CurPTHLexer)
    959     return CurPTHLexer->DiscardToEndOfLine();
    960 
    961   // Read the rest of the line raw.  We do this because we don't want macros
    962   // to be expanded and we don't require that the tokens be valid preprocessing
    963   // tokens.  For example, this is allowed: "#warning `   'foo".  GCC does
    964   // collapse multiple consequtive white space between tokens, but this isn't
    965   // specified by the standard.
    966   std::string Message = CurLexer->ReadToEndOfLine();
    967   if (isWarning)
    968     Diag(Tok, diag::pp_hash_warning) << Message;
    969   else
    970     Diag(Tok, diag::err_pp_hash_error) << Message;
    971 }
    972 
    973 /// HandleIdentSCCSDirective - Handle a #ident/#sccs directive.
    974 ///
    975 void Preprocessor::HandleIdentSCCSDirective(Token &Tok) {
    976   // Yes, this directive is an extension.
    977   Diag(Tok, diag::ext_pp_ident_directive);
    978 
    979   // Read the string argument.
    980   Token StrTok;
    981   Lex(StrTok);
    982 
    983   // If the token kind isn't a string, it's a malformed directive.
    984   if (StrTok.isNot(tok::string_literal) &&
    985       StrTok.isNot(tok::wide_string_literal)) {
    986     Diag(StrTok, diag::err_pp_malformed_ident);
    987     if (StrTok.isNot(tok::eod))
    988       DiscardUntilEndOfDirective();
    989     return;
    990   }
    991 
    992   // Verify that there is nothing after the string, other than EOD.
    993   CheckEndOfDirective("ident");
    994 
    995   if (Callbacks) {
    996     bool Invalid = false;
    997     std::string Str = getSpelling(StrTok, &Invalid);
    998     if (!Invalid)
    999       Callbacks->Ident(Tok.getLocation(), Str);
   1000   }
   1001 }
   1002 
   1003 //===----------------------------------------------------------------------===//
   1004 // Preprocessor Include Directive Handling.
   1005 //===----------------------------------------------------------------------===//
   1006 
   1007 /// GetIncludeFilenameSpelling - Turn the specified lexer token into a fully
   1008 /// checked and spelled filename, e.g. as an operand of #include. This returns
   1009 /// true if the input filename was in <>'s or false if it were in ""'s.  The
   1010 /// caller is expected to provide a buffer that is large enough to hold the
   1011 /// spelling of the filename, but is also expected to handle the case when
   1012 /// this method decides to use a different buffer.
   1013 bool Preprocessor::GetIncludeFilenameSpelling(SourceLocation Loc,
   1014                                               llvm::StringRef &Buffer) {
   1015   // Get the text form of the filename.
   1016   assert(!Buffer.empty() && "Can't have tokens with empty spellings!");
   1017 
   1018   // Make sure the filename is <x> or "x".
   1019   bool isAngled;
   1020   if (Buffer[0] == '<') {
   1021     if (Buffer.back() != '>') {
   1022       Diag(Loc, diag::err_pp_expects_filename);
   1023       Buffer = llvm::StringRef();
   1024       return true;
   1025     }
   1026     isAngled = true;
   1027   } else if (Buffer[0] == '"') {
   1028     if (Buffer.back() != '"') {
   1029       Diag(Loc, diag::err_pp_expects_filename);
   1030       Buffer = llvm::StringRef();
   1031       return true;
   1032     }
   1033     isAngled = false;
   1034   } else {
   1035     Diag(Loc, diag::err_pp_expects_filename);
   1036     Buffer = llvm::StringRef();
   1037     return true;
   1038   }
   1039 
   1040   // Diagnose #include "" as invalid.
   1041   if (Buffer.size() <= 2) {
   1042     Diag(Loc, diag::err_pp_empty_filename);
   1043     Buffer = llvm::StringRef();
   1044     return true;
   1045   }
   1046 
   1047   // Skip the brackets.
   1048   Buffer = Buffer.substr(1, Buffer.size()-2);
   1049   return isAngled;
   1050 }
   1051 
   1052 /// ConcatenateIncludeName - Handle cases where the #include name is expanded
   1053 /// from a macro as multiple tokens, which need to be glued together.  This
   1054 /// occurs for code like:
   1055 ///    #define FOO <a/b.h>
   1056 ///    #include FOO
   1057 /// because in this case, "<a/b.h>" is returned as 7 tokens, not one.
   1058 ///
   1059 /// This code concatenates and consumes tokens up to the '>' token.  It returns
   1060 /// false if the > was found, otherwise it returns true if it finds and consumes
   1061 /// the EOD marker.
   1062 bool Preprocessor::ConcatenateIncludeName(
   1063                                         llvm::SmallString<128> &FilenameBuffer,
   1064                                           SourceLocation &End) {
   1065   Token CurTok;
   1066 
   1067   Lex(CurTok);
   1068   while (CurTok.isNot(tok::eod)) {
   1069     End = CurTok.getLocation();
   1070 
   1071     // FIXME: Provide code completion for #includes.
   1072     if (CurTok.is(tok::code_completion)) {
   1073       Lex(CurTok);
   1074       continue;
   1075     }
   1076 
   1077     // Append the spelling of this token to the buffer. If there was a space
   1078     // before it, add it now.
   1079     if (CurTok.hasLeadingSpace())
   1080       FilenameBuffer.push_back(' ');
   1081 
   1082     // Get the spelling of the token, directly into FilenameBuffer if possible.
   1083     unsigned PreAppendSize = FilenameBuffer.size();
   1084     FilenameBuffer.resize(PreAppendSize+CurTok.getLength());
   1085 
   1086     const char *BufPtr = &FilenameBuffer[PreAppendSize];
   1087     unsigned ActualLen = getSpelling(CurTok, BufPtr);
   1088 
   1089     // If the token was spelled somewhere else, copy it into FilenameBuffer.
   1090     if (BufPtr != &FilenameBuffer[PreAppendSize])
   1091       memcpy(&FilenameBuffer[PreAppendSize], BufPtr, ActualLen);
   1092 
   1093     // Resize FilenameBuffer to the correct size.
   1094     if (CurTok.getLength() != ActualLen)
   1095       FilenameBuffer.resize(PreAppendSize+ActualLen);
   1096 
   1097     // If we found the '>' marker, return success.
   1098     if (CurTok.is(tok::greater))
   1099       return false;
   1100 
   1101     Lex(CurTok);
   1102   }
   1103 
   1104   // If we hit the eod marker, emit an error and return true so that the caller
   1105   // knows the EOD has been read.
   1106   Diag(CurTok.getLocation(), diag::err_pp_expects_filename);
   1107   return true;
   1108 }
   1109 
   1110 /// HandleIncludeDirective - The "#include" tokens have just been read, read the
   1111 /// file to be included from the lexer, then include it!  This is a common
   1112 /// routine with functionality shared between #include, #include_next and
   1113 /// #import.  LookupFrom is set when this is a #include_next directive, it
   1114 /// specifies the file to start searching from.
   1115 void Preprocessor::HandleIncludeDirective(SourceLocation HashLoc,
   1116                                           Token &IncludeTok,
   1117                                           const DirectoryLookup *LookupFrom,
   1118                                           bool isImport) {
   1119 
   1120   Token FilenameTok;
   1121   CurPPLexer->LexIncludeFilename(FilenameTok);
   1122 
   1123   // Reserve a buffer to get the spelling.
   1124   llvm::SmallString<128> FilenameBuffer;
   1125   llvm::StringRef Filename;
   1126   SourceLocation End;
   1127 
   1128   switch (FilenameTok.getKind()) {
   1129   case tok::eod:
   1130     // If the token kind is EOD, the error has already been diagnosed.
   1131     return;
   1132 
   1133   case tok::angle_string_literal:
   1134   case tok::string_literal:
   1135     Filename = getSpelling(FilenameTok, FilenameBuffer);
   1136     End = FilenameTok.getLocation();
   1137     break;
   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 (ConcatenateIncludeName(FilenameBuffer, End))
   1144       return;   // Found <eod> but no ">"?  Diagnostic already emitted.
   1145     Filename = FilenameBuffer.str();
   1146     break;
   1147   default:
   1148     Diag(FilenameTok.getLocation(), diag::err_pp_expects_filename);
   1149     DiscardUntilEndOfDirective();
   1150     return;
   1151   }
   1152 
   1153   bool isAngled =
   1154     GetIncludeFilenameSpelling(FilenameTok.getLocation(), Filename);
   1155   // If GetIncludeFilenameSpelling set the start ptr to null, there was an
   1156   // error.
   1157   if (Filename.empty()) {
   1158     DiscardUntilEndOfDirective();
   1159     return;
   1160   }
   1161 
   1162   // Verify that there is nothing after the filename, other than EOD.  Note that
   1163   // we allow macros that expand to nothing after the filename, because this
   1164   // falls into the category of "#include pp-tokens new-line" specified in
   1165   // C99 6.10.2p4.
   1166   CheckEndOfDirective(IncludeTok.getIdentifierInfo()->getNameStart(), true);
   1167 
   1168   // Check that we don't have infinite #include recursion.
   1169   if (IncludeMacroStack.size() == MaxAllowedIncludeStackDepth-1) {
   1170     Diag(FilenameTok, diag::err_pp_include_too_deep);
   1171     return;
   1172   }
   1173 
   1174   // Search include directories.
   1175   const DirectoryLookup *CurDir;
   1176   llvm::SmallString<1024> SearchPath;
   1177   llvm::SmallString<1024> RelativePath;
   1178   // We get the raw path only if we have 'Callbacks' to which we later pass
   1179   // the path.
   1180   const FileEntry *File = LookupFile(
   1181       Filename, isAngled, LookupFrom, CurDir,
   1182       Callbacks ? &SearchPath : NULL, Callbacks ? &RelativePath : NULL);
   1183 
   1184   // Notify the callback object that we've seen an inclusion directive.
   1185   if (Callbacks)
   1186     Callbacks->InclusionDirective(HashLoc, IncludeTok, Filename, isAngled, File,
   1187                                   End, SearchPath, RelativePath);
   1188 
   1189   if (File == 0) {
   1190     Diag(FilenameTok, diag::warn_pp_file_not_found) << Filename;
   1191     return;
   1192   }
   1193 
   1194   // The #included file will be considered to be a system header if either it is
   1195   // in a system include directory, or if the #includer is a system include
   1196   // header.
   1197   SrcMgr::CharacteristicKind FileCharacter =
   1198     std::max(HeaderInfo.getFileDirFlavor(File),
   1199              SourceMgr.getFileCharacteristic(FilenameTok.getLocation()));
   1200 
   1201   // Ask HeaderInfo if we should enter this #include file.  If not, #including
   1202   // this file will have no effect.
   1203   if (!HeaderInfo.ShouldEnterIncludeFile(File, isImport)) {
   1204     if (Callbacks)
   1205       Callbacks->FileSkipped(*File, FilenameTok, FileCharacter);
   1206     return;
   1207   }
   1208 
   1209   // Look up the file, create a File ID for it.
   1210   FileID FID = SourceMgr.createFileID(File, FilenameTok.getLocation(),
   1211                                       FileCharacter);
   1212   assert(!FID.isInvalid() && "Expected valid file ID");
   1213 
   1214   // Finally, if all is good, enter the new file!
   1215   EnterSourceFile(FID, CurDir, FilenameTok.getLocation());
   1216 }
   1217 
   1218 /// HandleIncludeNextDirective - Implements #include_next.
   1219 ///
   1220 void Preprocessor::HandleIncludeNextDirective(SourceLocation HashLoc,
   1221                                               Token &IncludeNextTok) {
   1222   Diag(IncludeNextTok, diag::ext_pp_include_next_directive);
   1223 
   1224   // #include_next is like #include, except that we start searching after
   1225   // the current found directory.  If we can't do this, issue a
   1226   // diagnostic.
   1227   const DirectoryLookup *Lookup = CurDirLookup;
   1228   if (isInPrimaryFile()) {
   1229     Lookup = 0;
   1230     Diag(IncludeNextTok, diag::pp_include_next_in_primary);
   1231   } else if (Lookup == 0) {
   1232     Diag(IncludeNextTok, diag::pp_include_next_absolute_path);
   1233   } else {
   1234     // Start looking up in the next directory.
   1235     ++Lookup;
   1236   }
   1237 
   1238   return HandleIncludeDirective(HashLoc, IncludeNextTok, Lookup);
   1239 }
   1240 
   1241 /// HandleImportDirective - Implements #import.
   1242 ///
   1243 void Preprocessor::HandleImportDirective(SourceLocation HashLoc,
   1244                                          Token &ImportTok) {
   1245   if (!Features.ObjC1)  // #import is standard for ObjC.
   1246     Diag(ImportTok, diag::ext_pp_import_directive);
   1247 
   1248   return HandleIncludeDirective(HashLoc, ImportTok, 0, true);
   1249 }
   1250 
   1251 /// HandleIncludeMacrosDirective - The -imacros command line option turns into a
   1252 /// pseudo directive in the predefines buffer.  This handles it by sucking all
   1253 /// tokens through the preprocessor and discarding them (only keeping the side
   1254 /// effects on the preprocessor).
   1255 void Preprocessor::HandleIncludeMacrosDirective(SourceLocation HashLoc,
   1256                                                 Token &IncludeMacrosTok) {
   1257   // This directive should only occur in the predefines buffer.  If not, emit an
   1258   // error and reject it.
   1259   SourceLocation Loc = IncludeMacrosTok.getLocation();
   1260   if (strcmp(SourceMgr.getBufferName(Loc), "<built-in>") != 0) {
   1261     Diag(IncludeMacrosTok.getLocation(),
   1262          diag::pp_include_macros_out_of_predefines);
   1263     DiscardUntilEndOfDirective();
   1264     return;
   1265   }
   1266 
   1267   // Treat this as a normal #include for checking purposes.  If this is
   1268   // successful, it will push a new lexer onto the include stack.
   1269   HandleIncludeDirective(HashLoc, IncludeMacrosTok, 0, false);
   1270 
   1271   Token TmpTok;
   1272   do {
   1273     Lex(TmpTok);
   1274     assert(TmpTok.isNot(tok::eof) && "Didn't find end of -imacros!");
   1275   } while (TmpTok.isNot(tok::hashhash));
   1276 }
   1277 
   1278 //===----------------------------------------------------------------------===//
   1279 // Preprocessor Macro Directive Handling.
   1280 //===----------------------------------------------------------------------===//
   1281 
   1282 /// ReadMacroDefinitionArgList - The ( starting an argument list of a macro
   1283 /// definition has just been read.  Lex the rest of the arguments and the
   1284 /// closing ), updating MI with what we learn.  Return true if an error occurs
   1285 /// parsing the arg list.
   1286 bool Preprocessor::ReadMacroDefinitionArgList(MacroInfo *MI) {
   1287   llvm::SmallVector<IdentifierInfo*, 32> Arguments;
   1288 
   1289   Token Tok;
   1290   while (1) {
   1291     LexUnexpandedToken(Tok);
   1292     switch (Tok.getKind()) {
   1293     case tok::r_paren:
   1294       // Found the end of the argument list.
   1295       if (Arguments.empty())  // #define FOO()
   1296         return false;
   1297       // Otherwise we have #define FOO(A,)
   1298       Diag(Tok, diag::err_pp_expected_ident_in_arg_list);
   1299       return true;
   1300     case tok::ellipsis:  // #define X(... -> C99 varargs
   1301       // Warn if use of C99 feature in non-C99 mode.
   1302       if (!Features.C99) Diag(Tok, diag::ext_variadic_macro);
   1303 
   1304       // Lex the token after the identifier.
   1305       LexUnexpandedToken(Tok);
   1306       if (Tok.isNot(tok::r_paren)) {
   1307         Diag(Tok, diag::err_pp_missing_rparen_in_macro_def);
   1308         return true;
   1309       }
   1310       // Add the __VA_ARGS__ identifier as an argument.
   1311       Arguments.push_back(Ident__VA_ARGS__);
   1312       MI->setIsC99Varargs();
   1313       MI->setArgumentList(&Arguments[0], Arguments.size(), BP);
   1314       return false;
   1315     case tok::eod:  // #define X(
   1316       Diag(Tok, diag::err_pp_missing_rparen_in_macro_def);
   1317       return true;
   1318     default:
   1319       // Handle keywords and identifiers here to accept things like
   1320       // #define Foo(for) for.
   1321       IdentifierInfo *II = Tok.getIdentifierInfo();
   1322       if (II == 0) {
   1323         // #define X(1
   1324         Diag(Tok, diag::err_pp_invalid_tok_in_arg_list);
   1325         return true;
   1326       }
   1327 
   1328       // If this is already used as an argument, it is used multiple times (e.g.
   1329       // #define X(A,A.
   1330       if (std::find(Arguments.begin(), Arguments.end(), II) !=
   1331           Arguments.end()) {  // C99 6.10.3p6
   1332         Diag(Tok, diag::err_pp_duplicate_name_in_arg_list) << II;
   1333         return true;
   1334       }
   1335 
   1336       // Add the argument to the macro info.
   1337       Arguments.push_back(II);
   1338 
   1339       // Lex the token after the identifier.
   1340       LexUnexpandedToken(Tok);
   1341 
   1342       switch (Tok.getKind()) {
   1343       default:          // #define X(A B
   1344         Diag(Tok, diag::err_pp_expected_comma_in_arg_list);
   1345         return true;
   1346       case tok::r_paren: // #define X(A)
   1347         MI->setArgumentList(&Arguments[0], Arguments.size(), BP);
   1348         return false;
   1349       case tok::comma:  // #define X(A,
   1350         break;
   1351       case tok::ellipsis:  // #define X(A... -> GCC extension
   1352         // Diagnose extension.
   1353         Diag(Tok, diag::ext_named_variadic_macro);
   1354 
   1355         // Lex the token after the identifier.
   1356         LexUnexpandedToken(Tok);
   1357         if (Tok.isNot(tok::r_paren)) {
   1358           Diag(Tok, diag::err_pp_missing_rparen_in_macro_def);
   1359           return true;
   1360         }
   1361 
   1362         MI->setIsGNUVarargs();
   1363         MI->setArgumentList(&Arguments[0], Arguments.size(), BP);
   1364         return false;
   1365       }
   1366     }
   1367   }
   1368 }
   1369 
   1370 /// HandleDefineDirective - Implements #define.  This consumes the entire macro
   1371 /// line then lets the caller lex the next real token.
   1372 void Preprocessor::HandleDefineDirective(Token &DefineTok) {
   1373   ++NumDefined;
   1374 
   1375   Token MacroNameTok;
   1376   ReadMacroName(MacroNameTok, 1);
   1377 
   1378   // Error reading macro name?  If so, diagnostic already issued.
   1379   if (MacroNameTok.is(tok::eod))
   1380     return;
   1381 
   1382   Token LastTok = MacroNameTok;
   1383 
   1384   // If we are supposed to keep comments in #defines, reenable comment saving
   1385   // mode.
   1386   if (CurLexer) CurLexer->SetCommentRetentionState(KeepMacroComments);
   1387 
   1388   // Create the new macro.
   1389   MacroInfo *MI = AllocateMacroInfo(MacroNameTok.getLocation());
   1390 
   1391   Token Tok;
   1392   LexUnexpandedToken(Tok);
   1393 
   1394   // If this is a function-like macro definition, parse the argument list,
   1395   // marking each of the identifiers as being used as macro arguments.  Also,
   1396   // check other constraints on the first token of the macro body.
   1397   if (Tok.is(tok::eod)) {
   1398     // If there is no body to this macro, we have no special handling here.
   1399   } else if (Tok.hasLeadingSpace()) {
   1400     // This is a normal token with leading space.  Clear the leading space
   1401     // marker on the first token to get proper expansion.
   1402     Tok.clearFlag(Token::LeadingSpace);
   1403   } else if (Tok.is(tok::l_paren)) {
   1404     // This is a function-like macro definition.  Read the argument list.
   1405     MI->setIsFunctionLike();
   1406     if (ReadMacroDefinitionArgList(MI)) {
   1407       // Forget about MI.
   1408       ReleaseMacroInfo(MI);
   1409       // Throw away the rest of the line.
   1410       if (CurPPLexer->ParsingPreprocessorDirective)
   1411         DiscardUntilEndOfDirective();
   1412       return;
   1413     }
   1414 
   1415     // If this is a definition of a variadic C99 function-like macro, not using
   1416     // the GNU named varargs extension, enabled __VA_ARGS__.
   1417 
   1418     // "Poison" __VA_ARGS__, which can only appear in the expansion of a macro.
   1419     // This gets unpoisoned where it is allowed.
   1420     assert(Ident__VA_ARGS__->isPoisoned() && "__VA_ARGS__ should be poisoned!");
   1421     if (MI->isC99Varargs())
   1422       Ident__VA_ARGS__->setIsPoisoned(false);
   1423 
   1424     // Read the first token after the arg list for down below.
   1425     LexUnexpandedToken(Tok);
   1426   } else if (Features.C99) {
   1427     // C99 requires whitespace between the macro definition and the body.  Emit
   1428     // a diagnostic for something like "#define X+".
   1429     Diag(Tok, diag::ext_c99_whitespace_required_after_macro_name);
   1430   } else {
   1431     // C90 6.8 TC1 says: "In the definition of an object-like macro, if the
   1432     // first character of a replacement list is not a character required by
   1433     // subclause 5.2.1, then there shall be white-space separation between the
   1434     // identifier and the replacement list.".  5.2.1 lists this set:
   1435     //   "A-Za-z0-9!"#%&'()*+,_./:;<=>?[\]^_{|}~" as well as whitespace, which
   1436     // is irrelevant here.
   1437     bool isInvalid = false;
   1438     if (Tok.is(tok::at)) // @ is not in the list above.
   1439       isInvalid = true;
   1440     else if (Tok.is(tok::unknown)) {
   1441       // If we have an unknown token, it is something strange like "`".  Since
   1442       // all of valid characters would have lexed into a single character
   1443       // token of some sort, we know this is not a valid case.
   1444       isInvalid = true;
   1445     }
   1446     if (isInvalid)
   1447       Diag(Tok, diag::ext_missing_whitespace_after_macro_name);
   1448     else
   1449       Diag(Tok, diag::warn_missing_whitespace_after_macro_name);
   1450   }
   1451 
   1452   if (!Tok.is(tok::eod))
   1453     LastTok = Tok;
   1454 
   1455   // Read the rest of the macro body.
   1456   if (MI->isObjectLike()) {
   1457     // Object-like macros are very simple, just read their body.
   1458     while (Tok.isNot(tok::eod)) {
   1459       LastTok = Tok;
   1460       MI->AddTokenToBody(Tok);
   1461       // Get the next token of the macro.
   1462       LexUnexpandedToken(Tok);
   1463     }
   1464 
   1465   } else {
   1466     // Otherwise, read the body of a function-like macro.  While we are at it,
   1467     // check C99 6.10.3.2p1: ensure that # operators are followed by macro
   1468     // parameters in function-like macro expansions.
   1469     while (Tok.isNot(tok::eod)) {
   1470       LastTok = Tok;
   1471 
   1472       if (Tok.isNot(tok::hash)) {
   1473         MI->AddTokenToBody(Tok);
   1474 
   1475         // Get the next token of the macro.
   1476         LexUnexpandedToken(Tok);
   1477         continue;
   1478       }
   1479 
   1480       // Get the next token of the macro.
   1481       LexUnexpandedToken(Tok);
   1482 
   1483       // Check for a valid macro arg identifier.
   1484       if (Tok.getIdentifierInfo() == 0 ||
   1485           MI->getArgumentNum(Tok.getIdentifierInfo()) == -1) {
   1486 
   1487         // If this is assembler-with-cpp mode, we accept random gibberish after
   1488         // the '#' because '#' is often a comment character.  However, change
   1489         // the kind of the token to tok::unknown so that the preprocessor isn't
   1490         // confused.
   1491         if (getLangOptions().AsmPreprocessor && Tok.isNot(tok::eod)) {
   1492           LastTok.setKind(tok::unknown);
   1493         } else {
   1494           Diag(Tok, diag::err_pp_stringize_not_parameter);
   1495           ReleaseMacroInfo(MI);
   1496 
   1497           // Disable __VA_ARGS__ again.
   1498           Ident__VA_ARGS__->setIsPoisoned(true);
   1499           return;
   1500         }
   1501       }
   1502 
   1503       // Things look ok, add the '#' and param name tokens to the macro.
   1504       MI->AddTokenToBody(LastTok);
   1505       MI->AddTokenToBody(Tok);
   1506       LastTok = Tok;
   1507 
   1508       // Get the next token of the macro.
   1509       LexUnexpandedToken(Tok);
   1510     }
   1511   }
   1512 
   1513 
   1514   // Disable __VA_ARGS__ again.
   1515   Ident__VA_ARGS__->setIsPoisoned(true);
   1516 
   1517   // Check that there is no paste (##) operator at the beginning or end of the
   1518   // replacement list.
   1519   unsigned NumTokens = MI->getNumTokens();
   1520   if (NumTokens != 0) {
   1521     if (MI->getReplacementToken(0).is(tok::hashhash)) {
   1522       Diag(MI->getReplacementToken(0), diag::err_paste_at_start);
   1523       ReleaseMacroInfo(MI);
   1524       return;
   1525     }
   1526     if (MI->getReplacementToken(NumTokens-1).is(tok::hashhash)) {
   1527       Diag(MI->getReplacementToken(NumTokens-1), diag::err_paste_at_end);
   1528       ReleaseMacroInfo(MI);
   1529       return;
   1530     }
   1531   }
   1532 
   1533   MI->setDefinitionEndLoc(LastTok.getLocation());
   1534 
   1535   // Finally, if this identifier already had a macro defined for it, verify that
   1536   // the macro bodies are identical and free the old definition.
   1537   if (MacroInfo *OtherMI = getMacroInfo(MacroNameTok.getIdentifierInfo())) {
   1538     // It is very common for system headers to have tons of macro redefinitions
   1539     // and for warnings to be disabled in system headers.  If this is the case,
   1540     // then don't bother calling MacroInfo::isIdenticalTo.
   1541     if (!getDiagnostics().getSuppressSystemWarnings() ||
   1542         !SourceMgr.isInSystemHeader(DefineTok.getLocation())) {
   1543       if (!OtherMI->isUsed() && OtherMI->isWarnIfUnused())
   1544         Diag(OtherMI->getDefinitionLoc(), diag::pp_macro_not_used);
   1545 
   1546       // Macros must be identical.  This means all tokens and whitespace
   1547       // separation must be the same.  C99 6.10.3.2.
   1548       if (!OtherMI->isAllowRedefinitionsWithoutWarning() &&
   1549           !MI->isIdenticalTo(*OtherMI, *this)) {
   1550         Diag(MI->getDefinitionLoc(), diag::ext_pp_macro_redef)
   1551           << MacroNameTok.getIdentifierInfo();
   1552         Diag(OtherMI->getDefinitionLoc(), diag::note_previous_definition);
   1553       }
   1554     }
   1555     if (OtherMI->isWarnIfUnused())
   1556       WarnUnusedMacroLocs.erase(OtherMI->getDefinitionLoc());
   1557     ReleaseMacroInfo(OtherMI);
   1558   }
   1559 
   1560   setMacroInfo(MacroNameTok.getIdentifierInfo(), MI);
   1561 
   1562   assert(!MI->isUsed());
   1563   // If we need warning for not using the macro, add its location in the
   1564   // warn-because-unused-macro set. If it gets used it will be removed from set.
   1565   if (isInPrimaryFile() && // don't warn for include'd macros.
   1566       Diags->getDiagnosticLevel(diag::pp_macro_not_used,
   1567                                MI->getDefinitionLoc()) != Diagnostic::Ignored) {
   1568     MI->setIsWarnIfUnused(true);
   1569     WarnUnusedMacroLocs.insert(MI->getDefinitionLoc());
   1570   }
   1571 
   1572   // If the callbacks want to know, tell them about the macro definition.
   1573   if (Callbacks)
   1574     Callbacks->MacroDefined(MacroNameTok, MI);
   1575 }
   1576 
   1577 /// HandleUndefDirective - Implements #undef.
   1578 ///
   1579 void Preprocessor::HandleUndefDirective(Token &UndefTok) {
   1580   ++NumUndefined;
   1581 
   1582   Token MacroNameTok;
   1583   ReadMacroName(MacroNameTok, 2);
   1584 
   1585   // Error reading macro name?  If so, diagnostic already issued.
   1586   if (MacroNameTok.is(tok::eod))
   1587     return;
   1588 
   1589   // Check to see if this is the last token on the #undef line.
   1590   CheckEndOfDirective("undef");
   1591 
   1592   // Okay, we finally have a valid identifier to undef.
   1593   MacroInfo *MI = getMacroInfo(MacroNameTok.getIdentifierInfo());
   1594 
   1595   // If the macro is not defined, this is a noop undef, just return.
   1596   if (MI == 0) return;
   1597 
   1598   if (!MI->isUsed() && MI->isWarnIfUnused())
   1599     Diag(MI->getDefinitionLoc(), diag::pp_macro_not_used);
   1600 
   1601   // If the callbacks want to know, tell them about the macro #undef.
   1602   if (Callbacks)
   1603     Callbacks->MacroUndefined(MacroNameTok, MI);
   1604 
   1605   if (MI->isWarnIfUnused())
   1606     WarnUnusedMacroLocs.erase(MI->getDefinitionLoc());
   1607 
   1608   // Free macro definition.
   1609   ReleaseMacroInfo(MI);
   1610   setMacroInfo(MacroNameTok.getIdentifierInfo(), 0);
   1611 }
   1612 
   1613 
   1614 //===----------------------------------------------------------------------===//
   1615 // Preprocessor Conditional Directive Handling.
   1616 //===----------------------------------------------------------------------===//
   1617 
   1618 /// HandleIfdefDirective - Implements the #ifdef/#ifndef directive.  isIfndef is
   1619 /// true when this is a #ifndef directive.  ReadAnyTokensBeforeDirective is true
   1620 /// if any tokens have been returned or pp-directives activated before this
   1621 /// #ifndef has been lexed.
   1622 ///
   1623 void Preprocessor::HandleIfdefDirective(Token &Result, bool isIfndef,
   1624                                         bool ReadAnyTokensBeforeDirective) {
   1625   ++NumIf;
   1626   Token DirectiveTok = Result;
   1627 
   1628   Token MacroNameTok;
   1629   ReadMacroName(MacroNameTok);
   1630 
   1631   // Error reading macro name?  If so, diagnostic already issued.
   1632   if (MacroNameTok.is(tok::eod)) {
   1633     // Skip code until we get to #endif.  This helps with recovery by not
   1634     // emitting an error when the #endif is reached.
   1635     SkipExcludedConditionalBlock(DirectiveTok.getLocation(),
   1636                                  /*Foundnonskip*/false, /*FoundElse*/false);
   1637     return;
   1638   }
   1639 
   1640   // Check to see if this is the last token on the #if[n]def line.
   1641   CheckEndOfDirective(isIfndef ? "ifndef" : "ifdef");
   1642 
   1643   IdentifierInfo *MII = MacroNameTok.getIdentifierInfo();
   1644   MacroInfo *MI = getMacroInfo(MII);
   1645 
   1646   if (CurPPLexer->getConditionalStackDepth() == 0) {
   1647     // If the start of a top-level #ifdef and if the macro is not defined,
   1648     // inform MIOpt that this might be the start of a proper include guard.
   1649     // Otherwise it is some other form of unknown conditional which we can't
   1650     // handle.
   1651     if (!ReadAnyTokensBeforeDirective && MI == 0) {
   1652       assert(isIfndef && "#ifdef shouldn't reach here");
   1653       CurPPLexer->MIOpt.EnterTopLevelIFNDEF(MII);
   1654     } else
   1655       CurPPLexer->MIOpt.EnterTopLevelConditional();
   1656   }
   1657 
   1658   // If there is a macro, process it.
   1659   if (MI)  // Mark it used.
   1660     markMacroAsUsed(MI);
   1661 
   1662   // Should we include the stuff contained by this directive?
   1663   if (!MI == isIfndef) {
   1664     // Yes, remember that we are inside a conditional, then lex the next token.
   1665     CurPPLexer->pushConditionalLevel(DirectiveTok.getLocation(),
   1666                                      /*wasskip*/false, /*foundnonskip*/true,
   1667                                      /*foundelse*/false);
   1668   } else {
   1669     // No, skip the contents of this block.
   1670     SkipExcludedConditionalBlock(DirectiveTok.getLocation(),
   1671                                  /*Foundnonskip*/false,
   1672                                  /*FoundElse*/false);
   1673   }
   1674 
   1675   if (Callbacks) {
   1676     if (isIfndef)
   1677       Callbacks->Ifndef(MacroNameTok);
   1678     else
   1679       Callbacks->Ifdef(MacroNameTok);
   1680   }
   1681 }
   1682 
   1683 /// HandleIfDirective - Implements the #if directive.
   1684 ///
   1685 void Preprocessor::HandleIfDirective(Token &IfToken,
   1686                                      bool ReadAnyTokensBeforeDirective) {
   1687   ++NumIf;
   1688 
   1689   // Parse and evaluate the conditional expression.
   1690   IdentifierInfo *IfNDefMacro = 0;
   1691   const SourceLocation ConditionalBegin = CurPPLexer->getSourceLocation();
   1692   const bool ConditionalTrue = EvaluateDirectiveExpression(IfNDefMacro);
   1693   const SourceLocation ConditionalEnd = CurPPLexer->getSourceLocation();
   1694 
   1695   // If this condition is equivalent to #ifndef X, and if this is the first
   1696   // directive seen, handle it for the multiple-include optimization.
   1697   if (CurPPLexer->getConditionalStackDepth() == 0) {
   1698     if (!ReadAnyTokensBeforeDirective && IfNDefMacro && ConditionalTrue)
   1699       CurPPLexer->MIOpt.EnterTopLevelIFNDEF(IfNDefMacro);
   1700     else
   1701       CurPPLexer->MIOpt.EnterTopLevelConditional();
   1702   }
   1703 
   1704   // Should we include the stuff contained by this directive?
   1705   if (ConditionalTrue) {
   1706     // Yes, remember that we are inside a conditional, then lex the next token.
   1707     CurPPLexer->pushConditionalLevel(IfToken.getLocation(), /*wasskip*/false,
   1708                                    /*foundnonskip*/true, /*foundelse*/false);
   1709   } else {
   1710     // No, skip the contents of this block.
   1711     SkipExcludedConditionalBlock(IfToken.getLocation(), /*Foundnonskip*/false,
   1712                                  /*FoundElse*/false);
   1713   }
   1714 
   1715   if (Callbacks)
   1716     Callbacks->If(SourceRange(ConditionalBegin, ConditionalEnd));
   1717 }
   1718 
   1719 /// HandleEndifDirective - Implements the #endif directive.
   1720 ///
   1721 void Preprocessor::HandleEndifDirective(Token &EndifToken) {
   1722   ++NumEndif;
   1723 
   1724   // Check that this is the whole directive.
   1725   CheckEndOfDirective("endif");
   1726 
   1727   PPConditionalInfo CondInfo;
   1728   if (CurPPLexer->popConditionalLevel(CondInfo)) {
   1729     // No conditionals on the stack: this is an #endif without an #if.
   1730     Diag(EndifToken, diag::err_pp_endif_without_if);
   1731     return;
   1732   }
   1733 
   1734   // If this the end of a top-level #endif, inform MIOpt.
   1735   if (CurPPLexer->getConditionalStackDepth() == 0)
   1736     CurPPLexer->MIOpt.ExitTopLevelConditional();
   1737 
   1738   assert(!CondInfo.WasSkipping && !CurPPLexer->LexingRawMode &&
   1739          "This code should only be reachable in the non-skipping case!");
   1740 
   1741   if (Callbacks)
   1742     Callbacks->Endif();
   1743 }
   1744 
   1745 /// HandleElseDirective - Implements the #else directive.
   1746 ///
   1747 void Preprocessor::HandleElseDirective(Token &Result) {
   1748   ++NumElse;
   1749 
   1750   // #else directive in a non-skipping conditional... start skipping.
   1751   CheckEndOfDirective("else");
   1752 
   1753   PPConditionalInfo CI;
   1754   if (CurPPLexer->popConditionalLevel(CI)) {
   1755     Diag(Result, diag::pp_err_else_without_if);
   1756     return;
   1757   }
   1758 
   1759   // If this is a top-level #else, inform the MIOpt.
   1760   if (CurPPLexer->getConditionalStackDepth() == 0)
   1761     CurPPLexer->MIOpt.EnterTopLevelConditional();
   1762 
   1763   // If this is a #else with a #else before it, report the error.
   1764   if (CI.FoundElse) Diag(Result, diag::pp_err_else_after_else);
   1765 
   1766   // Finally, skip the rest of the contents of this block.
   1767   SkipExcludedConditionalBlock(CI.IfLoc, /*Foundnonskip*/true,
   1768                                /*FoundElse*/true);
   1769 
   1770   if (Callbacks)
   1771     Callbacks->Else();
   1772 }
   1773 
   1774 /// HandleElifDirective - Implements the #elif directive.
   1775 ///
   1776 void Preprocessor::HandleElifDirective(Token &ElifToken) {
   1777   ++NumElse;
   1778 
   1779   // #elif directive in a non-skipping conditional... start skipping.
   1780   // We don't care what the condition is, because we will always skip it (since
   1781   // the block immediately before it was included).
   1782   const SourceLocation ConditionalBegin = CurPPLexer->getSourceLocation();
   1783   DiscardUntilEndOfDirective();
   1784   const SourceLocation ConditionalEnd = CurPPLexer->getSourceLocation();
   1785 
   1786   PPConditionalInfo CI;
   1787   if (CurPPLexer->popConditionalLevel(CI)) {
   1788     Diag(ElifToken, diag::pp_err_elif_without_if);
   1789     return;
   1790   }
   1791 
   1792   // If this is a top-level #elif, inform the MIOpt.
   1793   if (CurPPLexer->getConditionalStackDepth() == 0)
   1794     CurPPLexer->MIOpt.EnterTopLevelConditional();
   1795 
   1796   // If this is a #elif with a #else before it, report the error.
   1797   if (CI.FoundElse) Diag(ElifToken, diag::pp_err_elif_after_else);
   1798 
   1799   // Finally, skip the rest of the contents of this block.
   1800   SkipExcludedConditionalBlock(CI.IfLoc, /*Foundnonskip*/true,
   1801                                /*FoundElse*/CI.FoundElse);
   1802 
   1803   if (Callbacks)
   1804     Callbacks->Elif(SourceRange(ConditionalBegin, ConditionalEnd));
   1805 }
   1806