//===-- HeaderIncludeGen.cpp - Generate Header Includes -------------------===//

//

// 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

//

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

#include "clang/Frontend/DependencyOutputOptions.h"

#include "clang/Frontend/Utils.h"

#include "clang/Basic/SourceManager.h"

#include "clang/Frontend/FrontendDiagnostic.h"

#include "clang/Lex/Preprocessor.h"

#include "llvm/ADT/SmallString.h"

#include "llvm/Support/raw_ostream.h"

using namespace clang;

namespace {

class HeaderIncludesCallback : public PPCallbacks {

  SourceManager &SM;

  raw_ostream *OutputFile;

  const DependencyOutputOptions &DepOpts;

  unsigned CurrentIncludeDepth;

  bool HasProcessedPredefines;

  bool OwnsOutputFile;

  bool ShowAllHeaders;

  bool ShowDepth;

  bool MSStyle;

public:

  HeaderIncludesCallback(const Preprocessor *PP, bool ShowAllHeaders_,

                         raw_ostream *OutputFile_,

                         const DependencyOutputOptions &DepOpts,

                         bool OwnsOutputFile_, bool ShowDepth_, bool MSStyle_)

      : SM(PP->getSourceManager()), OutputFile(OutputFile_), DepOpts(DepOpts),

        CurrentIncludeDepth(0), HasProcessedPredefines(false),

        OwnsOutputFile(OwnsOutputFile_), ShowAllHeaders(ShowAllHeaders_),

        ShowDepth(ShowDepth_), MSStyle(MSStyle_) {}

  ~HeaderIncludesCallback() override {

    if (OwnsOutputFile)

      delete OutputFile;

  }

  void FileChanged(SourceLocation Loc, FileChangeReason Reason,

                   SrcMgr::CharacteristicKind FileType,

                   FileID PrevFID) override;

};

}

static void PrintHeaderInfo(raw_ostream *OutputFile, StringRef Filename,

                            bool ShowDepth, unsigned CurrentIncludeDepth,

                            bool MSStyle) {

  // Write to a temporary string to avoid unnecessary flushing on errs().

  SmallString<512> Pathname(Filename);

  if (!MSStyle)

    Lexer::Stringify(Pathname);

  SmallString<256> Msg;

  if (MSStyle)

    Msg += "Note: including file:";

  if (ShowDepth) {

    // The main source file is at depth 1, so skip one dot.

    for (unsigned i = 1; i != CurrentIncludeDepth; 
++i39
)

      Msg += MSStyle ? 
' '29
 : 
'.'10
;

    if (!MSStyle)

      Msg += ' ';

  }

  Msg += Pathname;

  Msg += '\n';

  *OutputFile << Msg;

  OutputFile->flush();

}

void clang::AttachHeaderIncludeGen(Preprocessor &PP,

                                   const DependencyOutputOptions &DepOpts,

                                   bool ShowAllHeaders, StringRef OutputPath,

                                   bool ShowDepth, bool MSStyle) {

  raw_ostream *OutputFile = &llvm::errs();

  bool OwnsOutputFile = false;

  // Choose output stream, when printing in cl.exe /showIncludes style.

  if (MSStyle) {

    switch (DepOpts.ShowIncludesDest) {

    default:

      llvm_unreachable("Invalid destination for /showIncludes output!");

    case ShowIncludesDestination::Stderr:

      OutputFile = &llvm::errs();

      break;

    case ShowIncludesDestination::Stdout:

      OutputFile = &llvm::outs();

      break;

    }

  }

  // Open the output file, if used.

  if (!OutputPath.empty()) {

    std::error_code EC;

    llvm::raw_fd_ostream *OS = new llvm::raw_fd_ostream(

        OutputPath.str(), EC,

        llvm::sys::fs::OF_Append | llvm::sys::fs::OF_Text);

    if (EC) {

      PP.getDiagnostics().Report(clang::diag::warn_fe_cc_print_header_failure)

          << EC.message();

      delete OS;

    } else {

      OS->SetUnbuffered();

      OutputFile = OS;

      OwnsOutputFile = true;

    }

  }

  // Print header info for extra headers, pretending they were discovered by

  // the regular preprocessor. The primary use case is to support proper

  // generation of Make / Ninja file dependencies for implicit includes, such

  // as sanitizer blacklists. It's only important for cl.exe compatibility,

  // the GNU way to generate rules is -M / -MM / -MD / -MMD.

  for (const auto &Header : DepOpts.ExtraDeps)

    PrintHeaderInfo(OutputFile, Header, ShowDepth, 2, MSStyle);

  PP.addPPCallbacks(std::make_unique<HeaderIncludesCallback>(

      &PP, ShowAllHeaders, OutputFile, DepOpts, OwnsOutputFile, ShowDepth,

      MSStyle));

}

void HeaderIncludesCallback::FileChanged(SourceLocation Loc,

                                         FileChangeReason Reason,

                                         SrcMgr::CharacteristicKind NewFileType,

                                         FileID PrevFID) {

  // Unless we are exiting a #include, make sure to skip ahead to the line the

  // #include directive was at.

  PresumedLoc UserLoc = SM.getPresumedLoc(Loc);

  if (UserLoc.isInvalid())

    return;

  // Adjust the current include depth.

  if (Reason == PPCallbacks::EnterFile) {

    ++CurrentIncludeDepth;

  } else if (Reason == PPCallbacks::ExitFile) {

    if (CurrentIncludeDepth)

      --CurrentIncludeDepth;

    // We track when we are done with the predefines by watching for the first

    // place where we drop back to a nesting depth of 1.

    if (CurrentIncludeDepth == 1 && 
!HasProcessedPredefines38
) {

      if (!DepOpts.ShowIncludesPretendHeader.empty()) {

        PrintHeaderInfo(OutputFile, DepOpts.ShowIncludesPretendHeader,

                        ShowDepth, 2, MSStyle);

      }

      HasProcessedPredefines = true;

    }

    return;

  } else

    return;

  // Show the header if we are (a) past the predefines, or (b) showing all

  // headers and in the predefines at a depth past the initial file and command

  // line buffers.

  bool ShowHeader = (HasProcessedPredefines ||

                     (ShowAllHeaders && 
CurrentIncludeDepth > 255
));

  unsigned IncludeDepth = CurrentIncludeDepth;

  if (!HasProcessedPredefines)

    --IncludeDepth; // Ignore indent from <built-in>.

  else if (!DepOpts.ShowIncludesPretendHeader.empty())

    ++IncludeDepth; // Pretend inclusion by ShowIncludesPretendHeader.

  if (!DepOpts.IncludeSystemHeaders && 
isSystem(NewFileType)27
)

    ShowHeader = false;

  // Dump the header include information we are past the predefines buffer or

  // are showing all headers and this isn't the magic implicit <command line>

  // header.

  // FIXME: Identify headers in a more robust way than comparing their name to

  // "<command line>" and "<built-in>" in a bunch of places.

  if (ShowHeader && 
Reason == PPCallbacks::EnterFile45
 &&

      UserLoc.getFilename() != StringRef("<command line>")) {

    PrintHeaderInfo(OutputFile, UserLoc.getFilename(), ShowDepth, IncludeDepth,

                    MSStyle);

  }

}