//===--- PPLexerChange.cpp - Handle changing lexers in the preprocessor ---===//

//

// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.

// See https://llvm.org/LICENSE.txt for license information.

// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

//

//===----------------------------------------------------------------------===//

//

// This file implements pieces of the Preprocessor interface that manage the

// current lexer stack.

//

//===----------------------------------------------------------------------===//

#include "clang/Lex/Preprocessor.h"

#include "clang/Lex/PreprocessorOptions.h"

#include "clang/Basic/FileManager.h"

#include "clang/Basic/SourceManager.h"

#include "clang/Lex/HeaderSearch.h"

#include "clang/Lex/LexDiagnostic.h"

#include "clang/Lex/MacroInfo.h"

#include "llvm/ADT/StringSwitch.h"

#include "llvm/Support/FileSystem.h"

#include "llvm/Support/MemoryBuffer.h"

#include "llvm/Support/Path.h"

using namespace clang;

//===----------------------------------------------------------------------===//

// Miscellaneous Methods.

//===----------------------------------------------------------------------===//

/// isInPrimaryFile - Return true if we're in the top-level file, not in a

/// \#include.  This looks through macro expansions and active _Pragma lexers.

bool Preprocessor::isInPrimaryFile() const {

  if (IsFileLexer())

    return IncludeMacroStack.empty();

  // If there are any stacked lexers, we're in a #include.

  assert(IsFileLexer(IncludeMacroStack[0]) &&

         "Top level include stack isn't our primary lexer?");

  return std::none_of(

      IncludeMacroStack.begin() + 1, IncludeMacroStack.end(),

      [&](const IncludeStackInfo &ISI) -> bool { return IsFileLexer(ISI); });

}

/// getCurrentLexer - Return the current file lexer being lexed from.  Note

/// that this ignores any potentially active macro expansions and _Pragma

/// expansions going on at the time.

PreprocessorLexer *Preprocessor::getCurrentFileLexer() const {

  if (IsFileLexer())

    return CurPPLexer;

  // Look for a stacked lexer.

  
for (const IncludeStackInfo &ISI : llvm::reverse(IncludeMacroStack))13
 {

    if (IsFileLexer(ISI))

      return ISI.ThePPLexer;

  }

  return nullptr;

}

//===----------------------------------------------------------------------===//

// Methods for Entering and Callbacks for leaving various contexts

//===----------------------------------------------------------------------===//

/// EnterSourceFile - Add a source file to the top of the include stack and

/// start lexing tokens from it instead of the current buffer.

bool Preprocessor::EnterSourceFile(FileID FID, const DirectoryLookup *CurDir,

                                   SourceLocation Loc) {

  assert(!CurTokenLexer && "Cannot #include a file inside a macro!");

  ++NumEnteredSourceFiles;

  if (MaxIncludeStackDepth < IncludeMacroStack.size())

    MaxIncludeStackDepth = IncludeMacroStack.size();

  // Get the MemoryBuffer for this FID, if it fails, we fail.

  bool Invalid = false;

  const llvm::MemoryBuffer *InputFile =

    getSourceManager().getBuffer(FID, Loc, &Invalid);

  if (Invalid) {

    SourceLocation FileStart = SourceMgr.getLocForStartOfFile(FID);

    Diag(Loc, diag::err_pp_error_opening_file)

        << std::string(SourceMgr.getBufferName(FileStart)) << "";

    return true;

  }

  if (isCodeCompletionEnabled() &&

      SourceMgr.getFileEntryForID(FID) == CodeCompletionFile) {

    CodeCompletionFileLoc = SourceMgr.getLocForStartOfFile(FID);

    CodeCompletionLoc =

        CodeCompletionFileLoc.getLocWithOffset(CodeCompletionOffset);

  }

  EnterSourceFileWithLexer(new Lexer(FID, InputFile, *this), CurDir);

  return false;

}

/// EnterSourceFileWithLexer - Add a source file to the top of the include stack

///  and start lexing tokens from it instead of the current buffer.

void Preprocessor::EnterSourceFileWithLexer(Lexer *TheLexer,

                                            const DirectoryLookup *CurDir) {

  // Add the current lexer to the include stack.

  if (CurPPLexer || 
CurTokenLexer694k
)

    PushIncludeMacroStack();

  CurLexer.reset(TheLexer);

  CurPPLexer = TheLexer;

  CurDirLookup = CurDir;

  CurLexerSubmodule = nullptr;

  if (CurLexerKind != CLK_LexAfterModuleImport)

    CurLexerKind = CLK_Lexer;

  // Notify the client, if desired, that we are in a new source file.

  if (Callbacks && 
!CurLexer->Is_PragmaLexer1.69M
) {

    SrcMgr::CharacteristicKind FileType =

       SourceMgr.getFileCharacteristic(CurLexer->getFileLoc());

    Callbacks->FileChanged(CurLexer->getFileLoc(),

                           PPCallbacks::EnterFile, FileType);

  }

}

/// EnterMacro - Add a Macro to the top of the include stack and start lexing

/// tokens from it instead of the current buffer.

void Preprocessor::EnterMacro(Token &Tok, SourceLocation ILEnd,

                              MacroInfo *Macro, MacroArgs *Args) {

  std::unique_ptr<TokenLexer> TokLexer;

  if (NumCachedTokenLexers == 0) {

    TokLexer = std::make_unique<TokenLexer>(Tok, ILEnd, Macro, Args, *this);

  } else {

    TokLexer = std::move(TokenLexerCache[--NumCachedTokenLexers]);

    TokLexer->Init(Tok, ILEnd, Macro, Args);

  }

  PushIncludeMacroStack();

  CurDirLookup = nullptr;

  CurTokenLexer = std::move(TokLexer);

  if (CurLexerKind != CLK_LexAfterModuleImport)

    CurLexerKind = CLK_TokenLexer;

}

/// EnterTokenStream - Add a "macro" context to the top of the include stack,

/// which will cause the lexer to start returning the specified tokens.

///

/// If DisableMacroExpansion is true, tokens lexed from the token stream will

/// not be subject to further macro expansion.  Otherwise, these tokens will

/// be re-macro-expanded when/if expansion is enabled.

///

/// If OwnsTokens is false, this method assumes that the specified stream of

/// tokens has a permanent owner somewhere, so they do not need to be copied.

/// If it is true, it assumes the array of tokens is allocated with new[] and

/// must be freed.

///

void Preprocessor::EnterTokenStream(const Token *Toks, unsigned NumToks,

                                    bool DisableMacroExpansion, bool OwnsTokens,

                                    bool IsReinject) {

  if (CurLexerKind == CLK_CachingLexer) {

    if (CachedLexPos < CachedTokens.size()) {

      assert(IsReinject && "new tokens in the middle of cached stream");

      // We're entering tokens into the middle of our cached token stream. We

      // can't represent that, so just insert the tokens into the buffer.

      CachedTokens.insert(CachedTokens.begin() + CachedLexPos,

                          Toks, Toks + NumToks);

      if (OwnsTokens)

        delete [] Toks;

      return;

    }

    // New tokens are at the end of the cached token sequnece; insert the

    // token stream underneath the caching lexer.

    ExitCachingLexMode();

    EnterTokenStream(Toks, NumToks, DisableMacroExpansion, OwnsTokens,

                     IsReinject);

    EnterCachingLexMode();

    return;

  }

  // Create a macro expander to expand from the specified token stream.

  std::unique_ptr<TokenLexer> TokLexer;

  if (NumCachedTokenLexers == 0) {

    TokLexer = std::make_unique<TokenLexer>(

        Toks, NumToks, DisableMacroExpansion, OwnsTokens, IsReinject, *this);

  } else {

    TokLexer = std::move(TokenLexerCache[--NumCachedTokenLexers]);

    TokLexer->Init(Toks, NumToks, DisableMacroExpansion, OwnsTokens,

                   IsReinject);

  }

  // Save our current state.

  PushIncludeMacroStack();

  CurDirLookup = nullptr;

  CurTokenLexer = std::move(TokLexer);

  if (CurLexerKind != CLK_LexAfterModuleImport)

    CurLexerKind = CLK_TokenLexer;

}

/// Compute the relative path that names the given file relative to

/// the given directory.

static void computeRelativePath(FileManager &FM, const DirectoryEntry *Dir,

                                const FileEntry *File,

                                SmallString<128> &Result) {

  Result.clear();

  StringRef FilePath = File->getDir()->getName();

  StringRef Path = FilePath;

  while (!Path.empty()) {

    if (auto CurDir = FM.getDirectory(Path)) {

      if (*CurDir == Dir) {

        Result = FilePath.substr(Path.size());

        llvm::sys::path::append(Result,

                                llvm::sys::path::filename(File->getName()));

        return;

      }

    }

    Path = llvm::sys::path::parent_path(Path);

  }

  Result = File->getName();

}

void Preprocessor::PropagateLineStartLeadingSpaceInfo(Token &Result) {

  if (CurTokenLexer) {

    CurTokenLexer->PropagateLineStartLeadingSpaceInfo(Result);

    return;

  }

  if (CurLexer) {

    CurLexer->PropagateLineStartLeadingSpaceInfo(Result);

    return;

  }

  // FIXME: Handle other kinds of lexers?  It generally shouldn't matter,

  // but it might if they're empty?

}

/// Determine the location to use as the end of the buffer for a lexer.

///

/// If the file ends with a newline, form the EOF token on the newline itself,

/// rather than "on the line following it", which doesn't exist.  This makes

/// diagnostics relating to the end of file include the last file that the user

/// actually typed, which is goodness.

const char *Preprocessor::getCurLexerEndPos() {

  const char *EndPos = CurLexer->BufferEnd;

  if (EndPos != CurLexer->BufferStart &&

      (EndPos[-1] == '\n' || 
EndPos[-1] == '\r'23.9k
)) {

    --EndPos;

    // Handle \n\r and \r\n:

    if (EndPos != CurLexer->BufferStart &&

        (EndPos[-1] == '\n' || 
EndPos[-1] == '\r'104k
) &&

        EndPos[-1] != EndPos[0])

      --EndPos;

  }

  return EndPos;

}

static void collectAllSubModulesWithUmbrellaHeader(

    const Module &Mod, SmallVectorImpl<const Module *> &SubMods) {

  if (Mod.getUmbrellaHeader())

    SubMods.push_back(&Mod);

  for (auto *M : Mod.submodules())

    collectAllSubModulesWithUmbrellaHeader(*M, SubMods);

}

void Preprocessor::diagnoseMissingHeaderInUmbrellaDir(const Module &Mod) {

  const Module::Header &UmbrellaHeader = Mod.getUmbrellaHeader();

  assert(UmbrellaHeader.Entry && "Module must use umbrella header");

  const FileID &File = SourceMgr.translateFile(UmbrellaHeader.Entry);

  SourceLocation ExpectedHeadersLoc = SourceMgr.getLocForEndOfFile(File);

  if (getDiagnostics().isIgnored(diag::warn_uncovered_module_header,

                                 ExpectedHeadersLoc))

    return;

  ModuleMap &ModMap = getHeaderSearchInfo().getModuleMap();

  const DirectoryEntry *Dir = Mod.getUmbrellaDir().Entry;

  llvm::vfs::FileSystem &FS = FileMgr.getVirtualFileSystem();

  std::error_code EC;

  for (llvm::vfs::recursive_directory_iterator Entry(FS, Dir->getName(), EC),

       End;

       Entry != End && 
!EC704
; 
Entry.increment(EC)704
) {

    using llvm::StringSwitch;

    // Check whether this entry has an extension typically associated with

    // headers.

    if (!StringSwitch<bool>(llvm::sys::path::extension(Entry->path()))

             .Cases(".h", ".H", ".hh", ".hpp", true)

             .Default(false))

      continue;

    if (auto Header = getFileManager().getFile(Entry->path()))

      if (!getSourceManager().hasFileInfo(*Header)) {

        if (!ModMap.isHeaderInUnavailableModule(*Header)) {

          // Find the relative path that would access this header.

          SmallString<128> RelativePath;

          computeRelativePath(FileMgr, Dir, *Header, RelativePath);

          Diag(ExpectedHeadersLoc, diag::warn_uncovered_module_header)

              << Mod.getFullModuleName() << RelativePath;

        }

      }

  }

}

/// HandleEndOfFile - This callback is invoked when the lexer hits the end of

/// the current file.  This either returns the EOF token or pops a level off

/// the include stack and keeps going.

bool Preprocessor::HandleEndOfFile(Token &Result, bool isEndOfMacro) {

  assert(!CurTokenLexer &&

         "Ending a file when currently in a macro!");

  // If we have an unclosed module region from a pragma at the end of a

  // module, complain and close it now.

  const bool LeavingSubmodule = CurLexer && 
CurLexerSubmodule1.69M
;

  if ((LeavingSubmodule || 
IncludeMacroStack.empty()79.0M
) &&

      !BuildingSubmoduleStack.empty() &&

      BuildingSubmoduleStack.back().IsPragma) {

    Diag(BuildingSubmoduleStack.back().ImportLoc,

         diag::err_pp_module_begin_without_module_end);

    Module *M = LeaveSubmodule(/*ForPragma*/true);

    Result.startToken();

    const char *EndPos = getCurLexerEndPos();

    CurLexer->BufferPtr = EndPos;

    CurLexer->FormTokenWithChars(Result, EndPos, tok::annot_module_end);

    Result.setAnnotationEndLoc(Result.getLocation());

    Result.setAnnotationValue(M);

    return true;

  }

  // See if this file had a controlling macro.

  if (CurPPLexer) {  // Not ending a macro, ignore it.

    if (const IdentifierInfo *ControllingMacro =

          CurPPLexer->MIOpt.GetControllingMacroAtEndOfFile()) {

      // Okay, this has a controlling macro, remember in HeaderFileInfo.

      if (const FileEntry *FE = CurPPLexer->getFileEntry()) {

        HeaderInfo.SetFileControllingMacro(FE, ControllingMacro);

        if (MacroInfo *MI =

              getMacroInfo(const_cast<IdentifierInfo*>(ControllingMacro)))

          MI->setUsedForHeaderGuard(true);

        if (const IdentifierInfo *DefinedMacro =

              CurPPLexer->MIOpt.GetDefinedMacro()) {

          if (!isMacroDefined(ControllingMacro) &&

              DefinedMacro != ControllingMacro &&

              HeaderInfo.FirstTimeLexingFile(FE)) {

            // If the edit distance between the two macros is more than 50%,

            // DefinedMacro may not be header guard, or can be header guard of

            // another header file. Therefore, it maybe defining something

            // completely different. This can be observed in the wild when

            // handling feature macros or header guards in different files.

            const StringRef ControllingMacroName = ControllingMacro->getName();

            const StringRef DefinedMacroName = DefinedMacro->getName();

            const size_t MaxHalfLength = std::max(ControllingMacroName.size(),

                                                  DefinedMacroName.size()) / 2;

            const unsigned ED = ControllingMacroName.edit_distance(

                DefinedMacroName, true, MaxHalfLength);

            if (ED <= MaxHalfLength) {

              // Emit a warning for a bad header guard.

              Diag(CurPPLexer->MIOpt.GetMacroLocation(),

                   diag::warn_header_guard)

                  << CurPPLexer->MIOpt.GetMacroLocation() << ControllingMacro;

              Diag(CurPPLexer->MIOpt.GetDefinedLocation(),

                   diag::note_header_guard)

                  << CurPPLexer->MIOpt.GetDefinedLocation() << DefinedMacro

                  << ControllingMacro

                  << FixItHint::CreateReplacement(

                         CurPPLexer->MIOpt.GetDefinedLocation(),

                         ControllingMacro->getName());

            }

          }

        }

      }

    }

  }

  // Complain about reaching a true EOF within arc_cf_code_audited.

  // We don't want to complain about reaching the end of a macro

  // instantiation or a _Pragma.

  if (PragmaARCCFCodeAuditedInfo.second.isValid() && 
!isEndOfMacro22.3M
 &&

      !(CurLexer && CurLexer->Is_PragmaLexer)) {

    Diag(PragmaARCCFCodeAuditedInfo.second,

         diag::err_pp_eof_in_arc_cf_code_audited);

    // Recover by leaving immediately.

    PragmaARCCFCodeAuditedInfo = {nullptr, SourceLocation()};

  }

  // Complain about reaching a true EOF within assume_nonnull.

  // We don't want to complain about reaching the end of a macro

  // instantiation or a _Pragma.

  if (PragmaAssumeNonNullLoc.isValid() &&

      !isEndOfMacro && 
!(1
CurLexer1
 && 
CurLexer->Is_PragmaLexer1
)) {

    Diag(PragmaAssumeNonNullLoc, diag::err_pp_eof_in_assume_nonnull);

    // Recover by leaving immediately.

    PragmaAssumeNonNullLoc = SourceLocation();

  }

  bool LeavingPCHThroughHeader = false;

  // If this is a #include'd file, pop it off the include stack and continue

  // lexing the #includer file.

  if (!IncludeMacroStack.empty()) {

    // If we lexed the code-completion file, act as if we reached EOF.

    if (isCodeCompletionEnabled() && 
CurPPLexer2.10k
 &&

        SourceMgr.getLocForStartOfFile(CurPPLexer->getFileID()) ==

            CodeCompletionFileLoc) {

      assert(CurLexer && "Got EOF but no current lexer set!");

      Result.startToken();

      CurLexer->FormTokenWithChars(Result, CurLexer->BufferEnd, tok::eof);

      CurLexer.reset();

      CurPPLexer = nullptr;

      recomputeCurLexerKind();

      return true;

    }

    if (!isEndOfMacro && 
CurPPLexer998k
 &&

        (SourceMgr.getIncludeLoc(CurPPLexer->getFileID()).isValid() ||

         // Predefines file doesn't have a valid include location.

         (PredefinesFileID.isValid() &&

          
CurPPLexer->getFileID() == PredefinesFileID80.6k
))) {

      // Notify SourceManager to record the number of FileIDs that were created

      // during lexing of the #include'd file.

      unsigned NumFIDs =

          SourceMgr.local_sloc_entry_size() -

          CurPPLexer->getInitialNumSLocEntries() + 1/*#include'd file*/;

      SourceMgr.setNumCreatedFIDsForFileID(CurPPLexer->getFileID(), NumFIDs);

    }

    bool ExitedFromPredefinesFile = false;

    FileID ExitedFID;

    if (!isEndOfMacro && 
CurPPLexer998k
) {

      ExitedFID = CurPPLexer->getFileID();

      assert(PredefinesFileID.isValid() &&

             "HandleEndOfFile is called before PredefinesFileId is set");

      ExitedFromPredefinesFile = (PredefinesFileID == ExitedFID);

    }

    if (LeavingSubmodule) {

      // We're done with this submodule.

      Module *M = LeaveSubmodule(/*ForPragma*/false);

      // Notify the parser that we've left the module.

      const char *EndPos = getCurLexerEndPos();

      Result.startToken();

      CurLexer->BufferPtr = EndPos;

      CurLexer->FormTokenWithChars(Result, EndPos, tok::annot_module_end);

      Result.setAnnotationEndLoc(Result.getLocation());

      Result.setAnnotationValue(M);

    }

    bool FoundPCHThroughHeader = false;

    if (CurPPLexer && 
creatingPCHWithThroughHeader()1.61M
 &&

        isPCHThroughHeader(

            SourceMgr.getFileEntryForID(CurPPLexer->getFileID())))

      FoundPCHThroughHeader = true;

    // We're done with the #included file.

    RemoveTopOfLexerStack();

    // Propagate info about start-of-line/leading white-space/etc.

    PropagateLineStartLeadingSpaceInfo(Result);

    // Notify the client, if desired, that we are in a new source file.

    if (Callbacks && 
!isEndOfMacro79.0M
 && 
CurPPLexer997k
) {

      SrcMgr::CharacteristicKind FileType =

        SourceMgr.getFileCharacteristic(CurPPLexer->getSourceLocation());

      Callbacks->FileChanged(CurPPLexer->getSourceLocation(),

                             PPCallbacks::ExitFile, FileType, ExitedFID);

    }

    // Restore conditional stack from the preamble right after exiting from the

    // predefines file.

    if (ExitedFromPredefinesFile)

      replayPreambleConditionalStack();

    if (!isEndOfMacro && 
CurPPLexer998k
 && 
FoundPCHThroughHeader998k
 &&

        (isInPrimaryFile() ||

         
CurPPLexer->getFileID() == getPredefinesFileID()7
)) {

      // Leaving the through header. Continue directly to end of main file

      // processing.

      LeavingPCHThroughHeader = true;

    } else {

      // Client should lex another token unless we generated an EOM.

      return LeavingSubmodule;

    }

  }

  // If this is the end of the main file, form an EOF token.

  assert(CurLexer && "Got EOF but no current lexer set!");

  const char *EndPos = getCurLexerEndPos();

  Result.startToken();

  CurLexer->BufferPtr = EndPos;

  CurLexer->FormTokenWithChars(Result, EndPos, tok::eof);

  if (isCodeCompletionEnabled()) {

    // Inserting the code-completion point increases the source buffer by 1,

    // but the main FileID was created before inserting the point.

    // Compensate by reducing the EOF location by 1, otherwise the location

    // will point to the next FileID.

    // FIXME: This is hacky, the code-completion point should probably be

    // inserted before the main FileID is created.

    if (CurLexer->getFileLoc() == CodeCompletionFileLoc)

      Result.setLocation(Result.getLocation().getLocWithOffset(-1));

  }

  if (creatingPCHWithThroughHeader() && 
!LeavingPCHThroughHeader13
) {

    // Reached the end of the compilation without finding the through header.

    Diag(CurLexer->getFileLoc(), diag::err_pp_through_header_not_seen)

        << PPOpts->PCHThroughHeader << 0;

  }

  if (!isIncrementalProcessingEnabled())

    // We're done with lexing.

    CurLexer.reset();

  if (!isIncrementalProcessingEnabled())

    CurPPLexer = nullptr;

  if (TUKind == TU_Complete) {

    // This is the end of the top-level file. 'WarnUnusedMacroLocs' has

    // collected all macro locations that we need to warn because they are not

    // used.

    for (WarnUnusedMacroLocsTy::iterator

           I=WarnUnusedMacroLocs.begin(), E=WarnUnusedMacroLocs.end();

           I!=E; 
++I8
)

      Diag(*I, diag::pp_macro_not_used);

  }

  // If we are building a module that has an umbrella header, make sure that

  // each of the headers within the directory, including all submodules, is

  // covered by the umbrella header was actually included by the umbrella

  // header.

  if (Module *Mod = getCurrentModule()) {

    llvm::SmallVector<const Module *, 4> AllMods;

    collectAllSubModulesWithUmbrellaHeader(*Mod, AllMods);

    for (auto *M : AllMods)

      diagnoseMissingHeaderInUmbrellaDir(*M);

  }

  return true;

}

/// HandleEndOfTokenLexer - This callback is invoked when the current TokenLexer

/// hits the end of its token stream.

bool Preprocessor::HandleEndOfTokenLexer(Token &Result) {

  assert(CurTokenLexer && !CurPPLexer &&

         "Ending a macro when currently in a #include file!");

  if (!MacroExpandingLexersStack.empty() &&

      MacroExpandingLexersStack.back().first == CurTokenLexer.get())

    removeCachedMacroExpandedTokensOfLastLexer();

  // Delete or cache the now-dead macro expander.

  if (NumCachedTokenLexers == TokenLexerCacheSize)

    CurTokenLexer.reset();

  else

    TokenLexerCache[NumCachedTokenLexers++] = std::move(CurTokenLexer);

  // Handle this like a #include file being popped off the stack.

  return HandleEndOfFile(Result, true);

}

/// RemoveTopOfLexerStack - Pop the current lexer/macro exp off the top of the

/// lexer stack.  This should only be used in situations where the current

/// state of the top-of-stack lexer is unknown.

void Preprocessor::RemoveTopOfLexerStack() {

  assert(!IncludeMacroStack.empty() && "Ran out of stack entries to load");

  if (CurTokenLexer) {

    // Delete or cache the now-dead macro expander.

    if (NumCachedTokenLexers == TokenLexerCacheSize)

      CurTokenLexer.reset();

    else

      TokenLexerCache[NumCachedTokenLexers++] = std::move(CurTokenLexer);

  }

  PopIncludeMacroStack();

}

/// HandleMicrosoftCommentPaste - When the macro expander pastes together a

/// comment (/##/) in microsoft mode, this method handles updating the current

/// state, returning the token on the next source line.

void Preprocessor::HandleMicrosoftCommentPaste(Token &Tok) {

  assert(CurTokenLexer && !CurPPLexer &&

         "Pasted comment can only be formed from macro");

  // We handle this by scanning for the closest real lexer, switching it to

  // raw mode and preprocessor mode.  This will cause it to return \n as an

  // explicit EOD token.

  PreprocessorLexer *FoundLexer = nullptr;

  bool LexerWasInPPMode = false;

  for (const IncludeStackInfo &ISI : llvm::reverse(IncludeMacroStack)) {

    if (ISI.ThePPLexer == nullptr) 
continue2
;  // Scan for a real lexer.

    // Once we find a real lexer, mark it as raw mode (disabling macro

    // expansions) and preprocessor mode (return EOD).  We know that the lexer

    // was *not* in raw mode before, because the macro that the comment came

    // from was expanded.  However, it could have already been in preprocessor

    // mode (#if COMMENT) in which case we have to return it to that mode and

    // return EOD.

    FoundLexer = ISI.ThePPLexer;

    FoundLexer->LexingRawMode = true;

    LexerWasInPPMode = FoundLexer->ParsingPreprocessorDirective;

    FoundLexer->ParsingPreprocessorDirective = true;

    break;

  }

  // Okay, we either found and switched over the lexer, or we didn't find a

  // lexer.  In either case, finish off the macro the comment came from, getting

  // the next token.

  if (!HandleEndOfTokenLexer(Tok)) Lex(Tok);

  // Discarding comments as long as we don't have EOF or EOD.  This 'comments

  // out' the rest of the line, including any tokens that came from other macros

  // that were active, as in:

  //  #define submacro a COMMENT b

  //    submacro c

  // which should lex to 'a' only: 'b' and 'c' should be removed.

  while (Tok.isNot(tok::eod) && 
Tok.isNot(tok::eof)26
)

    Lex(Tok);

  // If we got an eod token, then we successfully found the end of the line.

  if (Tok.is(tok::eod)) {

    assert(FoundLexer && "Can't get end of line without an active lexer");

    // Restore the lexer back to normal mode instead of raw mode.

    FoundLexer->LexingRawMode = false;

    // If the lexer was already in preprocessor mode, just return the EOD token

    // to finish the preprocessor line.

    if (LexerWasInPPMode) 
return0
;

    // Otherwise, switch out of PP mode and return the next lexed token.

    FoundLexer->ParsingPreprocessorDirective = false;

    return Lex(Tok);

  }

  // If we got an EOF token, then we reached the end of the token stream but

  // didn't find an explicit \n.  This can only happen if there was no lexer

  // active (an active lexer would return EOD at EOF if there was no \n in

  // preprocessor directive mode), so just return EOF as our token.

  assert(!FoundLexer && "Lexer should return EOD before EOF in PP mode");

}

void Preprocessor::EnterSubmodule(Module *M, SourceLocation ImportLoc,

                                  bool ForPragma) {

  if (!getLangOpts().ModulesLocalVisibility) {

    // Just track that we entered this submodule.

    BuildingSubmoduleStack.push_back(

        BuildingSubmoduleInfo(M, ImportLoc, ForPragma, CurSubmoduleState,

                              PendingModuleMacroNames.size()));

    if (Callbacks)

      Callbacks->EnteredSubmodule(M, ImportLoc, ForPragma);

    return;

  }

  // Resolve as much of the module definition as we can now, before we enter

  // one of its headers.

  // FIXME: Can we enable Complain here?

  // FIXME: Can we do this when local visibility is disabled?

  ModuleMap &ModMap = getHeaderSearchInfo().getModuleMap();

  ModMap.resolveExports(M, /*Complain=*/false);

  ModMap.resolveUses(M, /*Complain=*/false);

  ModMap.resolveConflicts(M, /*Complain=*/false);

  // If this is the first time we've entered this module, set up its state.

  auto R = Submodules.insert(std::make_pair(M, SubmoduleState()));

  auto &State = R.first->second;

  bool FirstTime = R.second;

  if (FirstTime) {

    // Determine the set of starting macros for this submodule; take these

    // from the "null" module (the predefines buffer).

    //

    // FIXME: If we have local visibility but not modules enabled, the

    // NullSubmoduleState is polluted by #defines in the top-level source

    // file.

    auto &StartingMacros = NullSubmoduleState.Macros;

    // Restore to the starting state.

    // FIXME: Do this lazily, when each macro name is first referenced.

    for (auto &Macro : StartingMacros) {

      // Skip uninteresting macros.

      if (!Macro.second.getLatest() &&

          Macro.second.getOverriddenMacros().empty())

        continue;

      MacroState MS(Macro.second.getLatest());

      MS.setOverriddenMacros(*this, Macro.second.getOverriddenMacros());

      State.Macros.insert(std::make_pair(Macro.first, std::move(MS)));

    }

  }

  // Track that we entered this module.

  BuildingSubmoduleStack.push_back(

      BuildingSubmoduleInfo(M, ImportLoc, ForPragma, CurSubmoduleState,

                            PendingModuleMacroNames.size()));

  if (Callbacks)

    Callbacks->EnteredSubmodule(M, ImportLoc, ForPragma);

  // Switch to this submodule as the current submodule.

  CurSubmoduleState = &State;

  // This module is visible to itself.

  if (FirstTime)

    makeModuleVisible(M, ImportLoc);

}

bool Preprocessor::needModuleMacros() const {

  // If we're not within a submodule, we never need to create ModuleMacros.

  if (BuildingSubmoduleStack.empty())

    return false;

  // If we are tracking module macro visibility even for textually-included

  // headers, we need ModuleMacros.

  if (getLangOpts().ModulesLocalVisibility)

    return true;

  // Otherwise, we only need module macros if we're actually compiling a module

  // interface.

  return getLangOpts().isCompilingModule();

}

Module *Preprocessor::LeaveSubmodule(bool ForPragma) {

  if (BuildingSubmoduleStack.empty() ||

      BuildingSubmoduleStack.back().IsPragma != ForPragma) {

    assert(ForPragma && "non-pragma module enter/leave mismatch");

    return nullptr;

  }

  auto &Info = BuildingSubmoduleStack.back();

  Module *LeavingMod = Info.M;

  SourceLocation ImportLoc = Info.ImportLoc;

  if (!needModuleMacros() ||

      (!getLangOpts().ModulesLocalVisibility &&

       LeavingMod->getTopLevelModuleName() != getLangOpts().CurrentModule)) {

    // If we don't need module macros, or this is not a module for which we

    // are tracking macro visibility, don't build any, and preserve the list

    // of pending names for the surrounding submodule.

    BuildingSubmoduleStack.pop_back();

    if (Callbacks)

      Callbacks->LeftSubmodule(LeavingMod, ImportLoc, ForPragma);

    makeModuleVisible(LeavingMod, ImportLoc);

    return LeavingMod;

  }

  // Create ModuleMacros for any macros defined in this submodule.

  llvm::SmallPtrSet<const IdentifierInfo*, 8> VisitedMacros;

  for (unsigned I = Info.OuterPendingModuleMacroNames;

       I != PendingModuleMacroNames.size(); 
++I336k
) {

    auto *II = const_cast<IdentifierInfo*>(PendingModuleMacroNames[I]);

    if (!VisitedMacros.insert(II).second)

      continue;

    auto MacroIt = CurSubmoduleState->Macros.find(II);

    if (MacroIt == CurSubmoduleState->Macros.end())

      continue;

    auto &Macro = MacroIt->second;

    // Find the starting point for the MacroDirective chain in this submodule.

    MacroDirective *OldMD = nullptr;

    auto *OldState = Info.OuterSubmoduleState;

    if (getLangOpts().ModulesLocalVisibility)

      OldState = &NullSubmoduleState;

    if (OldState && OldState != CurSubmoduleState) {

      // FIXME: It'd be better to start at the state from when we most recently

      // entered this submodule, but it doesn't really matter.

      auto &OldMacros = OldState->Macros;

      auto OldMacroIt = OldMacros.find(II);

      if (OldMacroIt == OldMacros.end())

        OldMD = nullptr;

      else

        OldMD = OldMacroIt->second.getLatest();

    }

    // This module may have exported a new macro. If so, create a ModuleMacro

    // representing that fact.

    bool ExplicitlyPublic = false;

    for (auto *MD = Macro.getLatest(); MD != OldMD; 
MD = MD->getPrevious()7
) {

      assert(MD && "broken macro directive chain");

      if (auto *VisMD = dyn_cast<VisibilityMacroDirective>(MD)) {

        // The latest visibility directive for a name in a submodule affects

        // all the directives that come before it.

        if (VisMD->isPublic())

          ExplicitlyPublic = true;

        else if (!ExplicitlyPublic)

          // Private with no following public directive: not exported.

          break;

      } else {

        MacroInfo *Def = nullptr;

        if (DefMacroDirective *DefMD = dyn_cast<DefMacroDirective>(MD))

          Def = DefMD->getInfo();

        // FIXME: Issue a warning if multiple headers for the same submodule

        // define a macro, rather than silently ignoring all but the first.

        bool IsNew;

        // Don't bother creating a module macro if it would represent a #undef

        // that doesn't override anything.

        if (Def || 
!Macro.getOverriddenMacros().empty()2.01k
)

          addModuleMacro(LeavingMod, II, Def,

                         Macro.getOverriddenMacros(), IsNew);

        if (!getLangOpts().ModulesLocalVisibility) {

          // This macro is exposed to the rest of this compilation as a

          // ModuleMacro; we don't need to track its MacroDirective any more.

          Macro.setLatest(nullptr);

          Macro.setOverriddenMacros(*this, {});

        }

        break;

      }

    }

  }

  PendingModuleMacroNames.resize(Info.OuterPendingModuleMacroNames);

  // FIXME: Before we leave this submodule, we should parse all the other

  // headers within it. Otherwise, we're left with an inconsistent state

  // where we've made the module visible but don't yet have its complete

  // contents.

  // Put back the outer module's state, if we're tracking it.

  if (getLangOpts().ModulesLocalVisibility)

    CurSubmoduleState = Info.OuterSubmoduleState;

  BuildingSubmoduleStack.pop_back();

  if (Callbacks)

    Callbacks->LeftSubmodule(LeavingMod, ImportLoc, ForPragma);

  // A nested #include makes the included submodule visible.

  makeModuleVisible(LeavingMod, ImportLoc);

  return LeavingMod;

}