CMake/Source/cmMakefileLibraryTargetGenerator.cxx

/*=========================================================================

  Program:   CMake - Cross-Platform Makefile Generator
  Module:    $RCSfile$
  Language:  C++
  Date:      $Date$
  Version:   $Revision$

  Copyright (c) 2002 Kitware, Inc., Insight Consortium.  All rights reserved.
  See Copyright.txt or http://www.cmake.org/HTML/Copyright.html for details.

     This software is distributed WITHOUT ANY WARRANTY; without even
     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
     PURPOSE.  See the above copyright notices for more information.

=========================================================================*/
#include "cmMakefileLibraryTargetGenerator.h"

#include "cmGeneratedFileStream.h"
#include "cmGlobalUnixMakefileGenerator3.h"
#include "cmLocalUnixMakefileGenerator3.h"
#include "cmMakefile.h"
#include "cmSourceFile.h"
#include "cmTarget.h"
#include "cmake.h"

#include <memory> // auto_ptr

//----------------------------------------------------------------------------
cmMakefileLibraryTargetGenerator::cmMakefileLibraryTargetGenerator()
{
  this->CustomCommandDriver = OnDepends;
}

//----------------------------------------------------------------------------
void cmMakefileLibraryTargetGenerator::WriteRuleFiles()
{
  // create the build.make file and directory, put in the common blocks
  this->CreateRuleFile();

  // write rules used to help build object files
  this->WriteCommonCodeRules();

  // write in rules for object files and custom commands
  this->WriteTargetBuildRules();

  // write the per-target per-language flags
  this->WriteTargetLanguageFlags();

  // write the link rules
  // Write the rule for this target type.
  switch(this->Target->GetType())
    {
    case cmTarget::STATIC_LIBRARY:
      this->WriteStaticLibraryRules();
      break;
    case cmTarget::SHARED_LIBRARY:
      this->WriteSharedLibraryRules(false);
      if(this->Target->NeedRelinkBeforeInstall())
        {
        // Write rules to link an installable version of the target.
        this->WriteSharedLibraryRules(true);
        }
      break;
    case cmTarget::MODULE_LIBRARY:
      this->WriteModuleLibraryRules(false);
      if(this->Target->NeedRelinkBeforeInstall())
        {
        // Write rules to link an installable version of the target.
        this->WriteModuleLibraryRules(true);
        }
      break;
    default:
      // If language is not known, this is an error.
      cmSystemTools::Error("Unknown Library Type");
      break;
    }

  // Write the requires target.
  this->WriteTargetRequiresRules();

  // Write clean target
  this->WriteTargetCleanRules();

  // Write the dependency generation rule.  This must be done last so
  // that multiple output pair information is available.
  this->WriteTargetDependRules();

  // close the streams
  this->CloseFileStreams();
}

//----------------------------------------------------------------------------
void cmMakefileLibraryTargetGenerator::WriteStaticLibraryRules()
{
  const char* linkLanguage =
    this->Target->GetLinkerLanguage(this->GlobalGenerator);
  std::string linkRuleVar = "CMAKE_";
  if (linkLanguage)
    {
    linkRuleVar += linkLanguage;
    }
  linkRuleVar += "_CREATE_STATIC_LIBRARY";

  std::string extraFlags;
  this->LocalGenerator->AppendFlags
    (extraFlags,this->Target->GetProperty("STATIC_LIBRARY_FLAGS"));
  this->WriteLibraryRules(linkRuleVar.c_str(), extraFlags.c_str(), false);
}

//----------------------------------------------------------------------------
void cmMakefileLibraryTargetGenerator::WriteSharedLibraryRules(bool relink)
{
#ifdef __APPLE__
  if (this->Target->GetPropertyAsBool("FRAMEWORK"))
    {
    this->WriteFrameworkRules(relink);
    return;
    }
#endif
  const char* linkLanguage =
    this->Target->GetLinkerLanguage(this->GlobalGenerator);
  std::string linkRuleVar = "CMAKE_";
  if (linkLanguage)
    {
    linkRuleVar += linkLanguage;
    }
  linkRuleVar += "_CREATE_SHARED_LIBRARY";

  std::string extraFlags;
  this->LocalGenerator->AppendFlags
    (extraFlags, this->Target->GetProperty("LINK_FLAGS"));
  std::string linkFlagsConfig = "LINK_FLAGS_";
  linkFlagsConfig += 
    cmSystemTools::UpperCase(this->LocalGenerator->ConfigurationName.c_str());
  this->LocalGenerator->AppendFlags
    (extraFlags, this->Target->GetProperty(linkFlagsConfig.c_str()));
                                    
  this->LocalGenerator->AddConfigVariableFlags
    (extraFlags, "CMAKE_SHARED_LINKER_FLAGS",
     this->LocalGenerator->ConfigurationName.c_str());
  if(this->Makefile->IsOn("WIN32") && !(this->Makefile->IsOn("CYGWIN") 
                                        || this->Makefile->IsOn("MINGW")))
    {
    const std::vector<cmSourceFile*>& sources = 
      this->Target->GetSourceFiles();
    for(std::vector<cmSourceFile*>::const_iterator i = sources.begin();
        i != sources.end(); ++i)
      {
      cmSourceFile* sf = *i;
      if(sf->GetExtension() == "def")
        {
        extraFlags += " ";
        extraFlags += 
          this->Makefile->GetSafeDefinition("CMAKE_LINK_DEF_FILE_FLAG");
        extraFlags += 
          this->Convert(sf->GetFullPath().c_str(),
                        cmLocalGenerator::START_OUTPUT,
                        cmLocalGenerator::SHELL);
        }
      }
    }
  this->WriteLibraryRules(linkRuleVar.c_str(), extraFlags.c_str(), relink);
}

//----------------------------------------------------------------------------
void cmMakefileLibraryTargetGenerator::WriteModuleLibraryRules(bool relink)
{
  const char* linkLanguage =
    this->Target->GetLinkerLanguage(this->GlobalGenerator);
  std::string linkRuleVar = "CMAKE_";
  if (linkLanguage)
    {
    linkRuleVar += linkLanguage;
    }
  linkRuleVar += "_CREATE_SHARED_MODULE";

  std::string extraFlags;
  this->LocalGenerator->AppendFlags(extraFlags, 
                                    this->Target->GetProperty("LINK_FLAGS"));
  std::string linkFlagsConfig = "LINK_FLAGS_";
  linkFlagsConfig += 
    cmSystemTools::UpperCase(this->LocalGenerator->ConfigurationName.c_str());
  this->LocalGenerator->AppendFlags
    (extraFlags, this->Target->GetProperty(linkFlagsConfig.c_str()));
  this->LocalGenerator->AddConfigVariableFlags
    (extraFlags, "CMAKE_MODULE_LINKER_FLAGS",
     this->LocalGenerator->ConfigurationName.c_str());

  // TODO: .def files should be supported here also.
  this->WriteLibraryRules(linkRuleVar.c_str(), extraFlags.c_str(), relink);
}

//----------------------------------------------------------------------------
void cmMakefileLibraryTargetGenerator::WriteFrameworkRules(bool relink)
{
  const char* linkLanguage =
    this->Target->GetLinkerLanguage(this->GlobalGenerator);
  std::string linkRuleVar = "CMAKE_";
  if (linkLanguage)
    {
    linkRuleVar += linkLanguage;
    }
  linkRuleVar += "_CREATE_MACOSX_FRAMEWORK";

  std::string extraFlags;
  this->LocalGenerator->AppendFlags(extraFlags, 
                                    this->Target->GetProperty("LINK_FLAGS"));
  std::string linkFlagsConfig = "LINK_FLAGS_";
  linkFlagsConfig += 
    cmSystemTools::UpperCase(this->LocalGenerator->ConfigurationName.c_str());
  this->LocalGenerator->AppendFlags
    (extraFlags, this->Target->GetProperty(linkFlagsConfig.c_str()));
  this->LocalGenerator->AddConfigVariableFlags
    (extraFlags, "CMAKE_MACOSX_FRAMEWORK_LINKER_FLAGS",
     this->LocalGenerator->ConfigurationName.c_str());

  // TODO: .def files should be supported here also.
  this->WriteLibraryRules(linkRuleVar.c_str(), extraFlags.c_str(), relink);
}

//----------------------------------------------------------------------------
void cmMakefileLibraryTargetGenerator::CreateFrameworkLinksAndDirs(
  std::string& targetName,
  std::string& outpath,
  const char* version)
{
  std::string symlink;
  std::string symlink2;
  // Make foo.framework/Versions
  std::string dir = outpath;
  dir += "Versions";
  cmSystemTools::MakeDirectory(dir.c_str());
  std::string cwd = cmSystemTools::GetCurrentWorkingDirectory();
  // cd foo.framework to setup symlinks with relative paths
  cmSystemTools::ChangeDirectory((outpath+"Versions").c_str());
  // Current -> version
  symlink = version;
  symlink2 = "Current";
  cmSystemTools::RemoveFile("Current");
  cmSystemTools::CreateSymlink(symlink.c_str(), symlink2.c_str());
  this->Makefile->AddCMakeOutputFile((outpath + "Versions/Current").c_str());
  // change to top level of framework to create next set of symlinks
  cmSystemTools::ChangeDirectory(outpath.c_str());
  // foo -> Versions/Current/foo
  symlink = "Versions/Current/";
  symlink += targetName;
  symlink2 = targetName;
  cmSystemTools::CreateSymlink(symlink.c_str(), symlink2.c_str());
  this->Makefile->AddCMakeOutputFile((outpath + targetName).c_str());
  // Resources -> Versions/Current/Resources 
  symlink = "Versions/Current/Resources";
  symlink2 = "Resources";
  cmSystemTools::CreateSymlink(symlink.c_str(), symlink2.c_str());
  this->Makefile->AddCMakeOutputFile((outpath + "Resources").c_str());
  // Headers -> Versions/Current/Headers
  symlink = "Versions/Current/Headers";
  symlink2 = "Headers";
  cmSystemTools::CreateSymlink(symlink.c_str(), symlink2.c_str());
  this->Makefile->AddCMakeOutputFile((outpath + "Headers").c_str());
  // PrivateHeaders -> Versions/Current/PrivateHeaders
  symlink = "Versions/Current/PrivateHeaders";
  symlink2 = "PrivateHeaders";
  cmSystemTools::CreateSymlink(symlink.c_str(), symlink2.c_str());
  this->Makefile->AddCMakeOutputFile((outpath + "PrivateHeaders").c_str());
  // go back to where we were
  cmSystemTools::ChangeDirectory(cwd.c_str());
}

//----------------------------------------------------------------------------
void cmMakefileLibraryTargetGenerator::CopyFrameworkSources(
  std::string& targetName,
  std::string& outpath,
  const char* /*version*/ ,
  const char* propertyName,
  const char* subdir)
{
  std::string fullOutput = outpath + targetName;
  cmCustomCommandLines commandLines;
  std::vector<std::string> depends;
  const std::vector<cmSourceFile*>& sources =
    this->Target->GetSourceFiles();

  std::string propName(propertyName);

  for(std::vector<cmSourceFile*>::const_iterator i = sources.begin();
      i != sources.end(); ++i)
    {
    cmSourceFile* sf = *i;

    if(!sf)
      {
      cmSystemTools::Error(
        "could not find framework source file", "");
      continue;
      }

    cmTarget::SourceFileFlags tsFlags =
      this->Target->GetTargetSourceFileFlags(sf);

    // If processing public headers, skip headers also marked with the private
    // property. Private wins.
    //
    if(tsFlags.PrivateHeader && (propName == "PUBLIC_HEADER"))
      {
      continue;
      }

    if(tsFlags.PrivateHeader && (propName == "PRIVATE_HEADER") ||
      tsFlags.PublicHeader && (propName == "PUBLIC_HEADER") ||
      tsFlags.Resource && (propName == "RESOURCE"))
      {
      cmCustomCommandLine line;
      std::string dest = outpath + subdir + "/";
      dest += cmSystemTools::GetFilenameName(sf->GetFullPath());
      line.push_back("$(CMAKE_COMMAND)");
      line.push_back("-E");
      line.push_back("copy_if_different");
      line.push_back(sf->GetFullPath());
      depends.push_back(sf->GetFullPath());
      line.push_back(dest);
      commandLines.push_back(line);
      // make sure the target gets rebuilt if any of the headers is removed
      this->GenerateExtraOutput(dest.c_str(), fullOutput.c_str());
      }
    }

  // add a set of prebuild commands to run on the target
  if(!commandLines.empty())
    {
    this->Makefile->
      AddCustomCommandToTarget(this->Target->GetName(),
                               depends,
                               commandLines,
                               cmTarget::PRE_BUILD,
                               "copy files",
                               this->Makefile->GetCurrentOutputDirectory());
    }
}

//----------------------------------------------------------------------------
void cmMakefileLibraryTargetGenerator::CreateFramework(
  std::string& targetName,
  std::string& outpath)
{
  std::string macdir = outpath;
  const char* version = this->Target->GetProperty("FRAMEWORK_VERSION");
  if(!version)
    {
    version = this->Target->GetProperty("VERSION");
    }
  if(!version)
    {
    version = "A";
    }
  // create the symbolic links and directories
  this->CreateFrameworkLinksAndDirs(targetName,
                                          outpath,
                                          version);
  macdir += "Versions/";
  macdir += version;
  macdir += "/";
  outpath += "Versions/";
  outpath += version;
  outpath += "/";

  //cmSystemTools::MakeDirectory((macdir + "Libraries").c_str());
  cmSystemTools::MakeDirectory((macdir + "Headers").c_str());
  // Configure the Info.plist file.  Note that it needs the executable name
  // to be set
  std::string rsrcDir = macdir + "Resources/";
  cmSystemTools::MakeDirectory(rsrcDir.c_str());
  this->Makefile->AddDefinition("MACOSX_FRAMEWORK_NAME",
                                targetName.c_str());
  std::string f1 = 
    this->Makefile->GetModulesFile("MacOSXFrameworkInfo.plist.in");
  if ( f1.size() == 0 )
    {
    cmSystemTools::Error(
      "could not find Mac OSX framework Info.plist template file.");
    }
  std::string f2 = rsrcDir + "Info.plist";
  this->Makefile->ConfigureFile(f1.c_str(), f2.c_str(),
                                false, false, false);

  this->CopyFrameworkSources(targetName, outpath, version,
    "PRIVATE_HEADER", "PrivateHeaders");

  this->CopyFrameworkSources(targetName, outpath, version,
    "PUBLIC_HEADER", "Headers");

  this->CopyFrameworkSources(targetName, outpath, version,
    "RESOURCE", "Resources");
}

//----------------------------------------------------------------------------
void cmMakefileLibraryTargetGenerator::WriteLibraryRules
(const char* linkRuleVar, const char* extraFlags, bool relink)
{
  // TODO: Merge the methods that call this method to avoid
  // code duplication.
  std::vector<std::string> commands;

  std::string relPath = this->LocalGenerator->GetHomeRelativeOutputPath();
  std::string objTarget;

  // Build list of dependencies.
  std::vector<std::string> depends;
  for(std::vector<std::string>::const_iterator obj = this->Objects.begin();
      obj != this->Objects.end(); ++obj)
    {
    objTarget = relPath;
    objTarget += *obj;
    depends.push_back(objTarget);
    }

  // Add dependencies on targets that must be built first.
  this->AppendTargetDepends(depends);

  // Add a dependency on the rule file itself.
  this->LocalGenerator->AppendRuleDepend(depends, 
                                         this->BuildFileNameFull.c_str());
  
  for(std::vector<std::string>::const_iterator obj 
        = this->ExternalObjects.begin();
      obj != this->ExternalObjects.end(); ++obj)
    {
    depends.push_back(*obj);
    }
  
  // Get the language to use for linking this library.
  const char* linkLanguage =
    this->Target->GetLinkerLanguage(this->GlobalGenerator);

  // Make sure we have a link language.
  if(!linkLanguage)
    {
    cmSystemTools::Error("Cannot determine link language for target \"",
                         this->Target->GetName(), "\".");
    return;
    }

  // Create set of linking flags.
  std::string linkFlags;
  this->LocalGenerator->AppendFlags(linkFlags, extraFlags);

  // Construct the name of the library.
  std::string targetName;
  std::string targetNameSO;
  std::string targetNameReal;
  std::string targetNameImport;
  std::string targetNamePDB;
  this->Target->GetLibraryNames(
    targetName, targetNameSO, targetNameReal, targetNameImport, targetNamePDB,
    this->LocalGenerator->ConfigurationName.c_str());

  // Construct the full path version of the names.
  std::string outpath;
  std::string outpathImp;
  if(relink)
    {
    outpath = this->Makefile->GetStartOutputDirectory();
    outpath += cmake::GetCMakeFilesDirectory();
    outpath += "/CMakeRelink.dir";
    cmSystemTools::MakeDirectory(outpath.c_str());
    outpath += "/";
    if(!targetNameImport.empty())
      {
      outpathImp = outpath;
      }
    }
  else
    {
    outpath = this->Target->GetDirectory();
    outpath += "/";
    if(!targetNameImport.empty())
      {
      outpathImp = this->Target->GetDirectory(0, true);
      outpathImp += "/";
      }
    }
#if defined(__APPLE__)
  // If we're creating a framework, place the output into a framework directory
  if (this->Target->GetType() == cmTarget::SHARED_LIBRARY &&
      this->Target->GetPropertyAsBool("FRAMEWORK"))
    {
    this->CreateFramework(targetName, outpath);
    }
#endif
  std::string targetFullPath = outpath + targetName;
  std::string targetFullPathPDB = outpath + targetNamePDB;
  std::string targetFullPathSO = outpath + targetNameSO;
  std::string targetFullPathReal = outpath + targetNameReal;
  std::string targetFullPathImport = outpathImp + targetNameImport;

  // Construct the output path version of the names for use in command
  // arguments.
  std::string targetOutPathPDB = 
    this->Convert(targetFullPathPDB.c_str(),cmLocalGenerator::FULL,
                  cmLocalGenerator::SHELL);
  std::string targetOutPath = 
    this->Convert(targetFullPath.c_str(),cmLocalGenerator::START_OUTPUT,
                  cmLocalGenerator::SHELL);
  std::string targetOutPathSO = 
    this->Convert(targetFullPathSO.c_str(),cmLocalGenerator::START_OUTPUT,
                  cmLocalGenerator::SHELL);
  std::string targetOutPathReal = 
    this->Convert(targetFullPathReal.c_str(),cmLocalGenerator::START_OUTPUT,
                  cmLocalGenerator::SHELL);
  std::string targetOutPathImport =
    this->Convert(targetFullPathImport.c_str(),cmLocalGenerator::START_OUTPUT,
                  cmLocalGenerator::SHELL);

  // Add the link message.
  std::string buildEcho = "Linking ";
  buildEcho += linkLanguage;
  const char* forbiddenFlagVar = 0;
  switch(this->Target->GetType())
    {
    case cmTarget::STATIC_LIBRARY:
      buildEcho += " static library "; 
      break;
    case cmTarget::SHARED_LIBRARY:
      forbiddenFlagVar = "_CREATE_SHARED_LIBRARY_FORBIDDEN_FLAGS";
      buildEcho += " shared library ";
      break;
    case cmTarget::MODULE_LIBRARY:
      forbiddenFlagVar = "_CREATE_SHARED_MODULE_FORBIDDEN_FLAGS";
      buildEcho += " shared module ";
      break;
    default:
      buildEcho += " library "; 
      break;
    }
  buildEcho += targetOutPath.c_str();
  this->LocalGenerator->AppendEcho(commands, buildEcho.c_str(),
                                   cmLocalUnixMakefileGenerator3::EchoLink);

  // Construct a list of files associated with this library that may
  // need to be cleaned.
  std::vector<std::string> libCleanFiles;
  if(this->Target->GetPropertyAsBool("CLEAN_DIRECT_OUTPUT"))
    {
    // The user has requested that only the files directly built
    // by this target be cleaned instead of all possible names.
    libCleanFiles.push_back(this->Convert(targetFullPath.c_str(),
          cmLocalGenerator::START_OUTPUT,
          cmLocalGenerator::UNCHANGED));
    if(targetNameReal != targetName)
      {
      libCleanFiles.push_back(this->Convert(targetFullPathReal.c_str(),
          cmLocalGenerator::START_OUTPUT,
          cmLocalGenerator::UNCHANGED));
      }
    if(targetNameSO != targetName &&
       targetNameSO != targetNameReal)
      {
      libCleanFiles.push_back(this->Convert(targetFullPathSO.c_str(),
          cmLocalGenerator::START_OUTPUT,
          cmLocalGenerator::UNCHANGED));
      }
    if(!targetNameImport.empty())
      {
      libCleanFiles.push_back(this->Convert(targetFullPathImport.c_str(),
          cmLocalGenerator::START_OUTPUT,
          cmLocalGenerator::UNCHANGED));
      }
    }
  else
    {
    // This target may switch between static and shared based
    // on a user option or the BUILD_SHARED_LIBS switch.  Clean
    // all possible names.
    std::string cleanStaticName;
    std::string cleanSharedName;
    std::string cleanSharedSOName;
    std::string cleanSharedRealName;
    std::string cleanImportName;
    std::string cleanPDBName;
    this->Target->GetLibraryCleanNames(
      cleanStaticName,
      cleanSharedName,
      cleanSharedSOName,
      cleanSharedRealName,
      cleanImportName,
      cleanPDBName,
      this->LocalGenerator->ConfigurationName.c_str());
    std::string cleanFullStaticName = outpath + cleanStaticName;
    std::string cleanFullSharedName = outpath + cleanSharedName;
    std::string cleanFullSharedSOName = outpath + cleanSharedSOName;
    std::string cleanFullSharedRealName = outpath + cleanSharedRealName;
    std::string cleanFullImportName = outpathImp + cleanImportName;
    std::string cleanFullPDBName = outpath + cleanPDBName;
    libCleanFiles.push_back
      (this->Convert(cleanFullStaticName.c_str(),
                     cmLocalGenerator::START_OUTPUT,
                     cmLocalGenerator::UNCHANGED));
    if(cleanSharedRealName != cleanStaticName)
      {
      libCleanFiles.push_back(this->Convert(cleanFullSharedRealName.c_str(),
          cmLocalGenerator::START_OUTPUT,
          cmLocalGenerator::UNCHANGED));
      }
    if(cleanSharedSOName != cleanStaticName &&
      cleanSharedSOName != cleanSharedRealName)
      {
      libCleanFiles.push_back(this->Convert(cleanFullSharedSOName.c_str(),
          cmLocalGenerator::START_OUTPUT,
          cmLocalGenerator::UNCHANGED));
      }
    if(cleanSharedName != cleanStaticName &&
      cleanSharedName != cleanSharedSOName &&
      cleanSharedName != cleanSharedRealName)
      {
      libCleanFiles.push_back(this->Convert(cleanFullSharedName.c_str(),
          cmLocalGenerator::START_OUTPUT,
          cmLocalGenerator::UNCHANGED));
      }
    if(!cleanImportName.empty())
      {
      libCleanFiles.push_back(this->Convert(cleanFullImportName.c_str(),
          cmLocalGenerator::START_OUTPUT,
          cmLocalGenerator::UNCHANGED));
      }

    // List the PDB for cleaning only when the whole target is
    // cleaned.  We do not want to delete the .pdb file just before
    // linking the target.
    this->CleanFiles.push_back
      (this->Convert(cleanFullPDBName.c_str(),
                     cmLocalGenerator::START_OUTPUT,
                     cmLocalGenerator::UNCHANGED));
    }

#ifdef _WIN32
  // There may be a manifest file for this target.  Add it to the
  // clean set just in case.
  if(this->Target->GetType() != cmTarget::STATIC_LIBRARY)
    {
    libCleanFiles.push_back(
      this->Convert((targetFullPath+".manifest").c_str(),
                    cmLocalGenerator::START_OUTPUT,
                    cmLocalGenerator::UNCHANGED));
    }
#endif

  std::vector<std::string> commands1;
  // Add a command to remove any existing files for this library.
  // for static libs only 
  if(this->Target->GetType() == cmTarget::STATIC_LIBRARY)
    {
    this->LocalGenerator->AppendCleanCommand(commands1, libCleanFiles,
                                             *this->Target, "target");
    this->LocalGenerator->CreateCDCommand
      (commands1,
       this->Makefile->GetStartOutputDirectory(),
       this->Makefile->GetHomeOutputDirectory());
    commands.insert(commands.end(), commands1.begin(), commands1.end());
    commands1.clear();
    }

  // Add the pre-build and pre-link rules building but not when relinking.
  if(!relink)
    {
    this->LocalGenerator
      ->AppendCustomCommands(commands, this->Target->GetPreBuildCommands());
    this->LocalGenerator
      ->AppendCustomCommands(commands, this->Target->GetPreLinkCommands());
    }

  // Open the link script if it will be used.
  bool useLinkScript = false;
  std::string linkScriptName;
  std::auto_ptr<cmGeneratedFileStream> linkScriptStream;
  if(this->GlobalGenerator->GetUseLinkScript() &&
     (this->Target->GetType() == cmTarget::STATIC_LIBRARY ||
      this->Target->GetType() == cmTarget::SHARED_LIBRARY ||
      this->Target->GetType() == cmTarget::MODULE_LIBRARY))
    {
    useLinkScript = true;
    linkScriptName = this->TargetBuildDirectoryFull;
    if(relink)
      {
      linkScriptName += "/relink.txt";
      }
    else
      {
      linkScriptName += "/link.txt";
      }
    std::auto_ptr<cmGeneratedFileStream> lss(
      new cmGeneratedFileStream(linkScriptName.c_str()));
    linkScriptStream = lss;
    }

  std::vector<std::string> link_script_commands;

  // Construct the main link rule.
  std::string linkRule = this->Makefile->GetRequiredDefinition(linkRuleVar);
  if(useLinkScript)
    {
    cmSystemTools::ExpandListArgument(linkRule, link_script_commands);
    std::string link_command = "$(CMAKE_COMMAND) -E cmake_link_script ";
    link_command += this->Convert(linkScriptName.c_str(),
                                  cmLocalGenerator::START_OUTPUT,
                                  cmLocalGenerator::SHELL);
    link_command += " --verbose=$(VERBOSE)";
    commands1.push_back(link_command);
    }
  else
    {
    cmSystemTools::ExpandListArgument(linkRule, commands1);
    }
  this->LocalGenerator->CreateCDCommand
    (commands1,
     this->Makefile->GetStartOutputDirectory(),
     this->Makefile->GetHomeOutputDirectory());
  commands.insert(commands.end(), commands1.begin(), commands1.end());

  // Add a rule to create necessary symlinks for the library.
  if(targetOutPath != targetOutPathReal)
    {
    std::string symlink = "$(CMAKE_COMMAND) -E cmake_symlink_library ";
    symlink += targetOutPathReal;
    symlink += " ";
    symlink += targetOutPathSO;
    symlink += " ";
    symlink += targetOutPath;
    commands1.clear();
    commands1.push_back(symlink);
    this->LocalGenerator->CreateCDCommand(commands1,
                                  this->Makefile->GetStartOutputDirectory(),
                                  this->Makefile->GetHomeOutputDirectory());
    commands.insert(commands.end(), commands1.begin(), commands1.end());
    }
  // Add the post-build rules when building but not when relinking.
  if(!relink)
    {
    this->LocalGenerator->
      AppendCustomCommands(commands, this->Target->GetPostBuildCommands());
    }

  // Collect up flags to link in needed libraries.
  cmOStringStream linklibs;
  this->LocalGenerator->OutputLinkLibraries(linklibs, *this->Target, relink);

  // Construct object file lists that may be needed to expand the
  // rule.
  std::string variableName;
  std::string variableNameExternal;
  this->WriteObjectsVariable(variableName, variableNameExternal);
  std::string buildObjs;
  if(useLinkScript)
    {
    this->WriteObjectsString(buildObjs);
    }
  else
    {
    buildObjs = "$(";
    buildObjs += variableName;
    buildObjs += ") $(";
    buildObjs += variableNameExternal;
    buildObjs += ")";
    }
  std::string cleanObjs = "$(";
  cleanObjs += variableName;
  cleanObjs += ")";
  cmLocalGenerator::RuleVariables vars;
  vars.TargetPDB = targetOutPathPDB.c_str();

  // Setup the target version.
  std::string targetVersionMajor;
  std::string targetVersionMinor;
  {
  cmOStringStream majorStream;
  cmOStringStream minorStream;
  int major;
  int minor;
  this->Target->GetTargetVersion(major, minor);
  majorStream << major;
  minorStream << minor;
  targetVersionMajor = majorStream.str();
  targetVersionMinor = minorStream.str();
  }
  vars.TargetVersionMajor = targetVersionMajor.c_str();
  vars.TargetVersionMinor = targetVersionMinor.c_str();

  vars.Language = linkLanguage;
  vars.Objects = buildObjs.c_str();
  std::string objdir = cmake::GetCMakeFilesDirectoryPostSlash();
  objdir += this->Target->GetName();
  objdir += ".dir";
  vars.ObjectDir = objdir.c_str(); 
  vars.Target = targetOutPathReal.c_str();
  std::string linkString = linklibs.str();
  vars.LinkLibraries = linkString.c_str();
  vars.ObjectsQuoted = buildObjs.c_str();
  vars.TargetSOName= targetNameSO.c_str();
  vars.LinkFlags = linkFlags.c_str();

  // Compute the directory portion of the install_name setting.
  std::string install_name_dir;
  if(this->Target->GetType() == cmTarget::SHARED_LIBRARY)
    {
    // Get the install_name directory for the build tree.
    const char* config = this->LocalGenerator->ConfigurationName.c_str();
    install_name_dir = this->Target->GetInstallNameDirForBuildTree(config);

    // Set the rule variable replacement value.
    if(install_name_dir.empty())
      {
      vars.TargetInstallNameDir = "";
      }
    else
      {
      // Convert to a path for the native build tool.
      install_name_dir =
        this->LocalGenerator->Convert(install_name_dir.c_str(),
                                      cmLocalGenerator::NONE,
                                      cmLocalGenerator::SHELL, false);
      vars.TargetInstallNameDir = install_name_dir.c_str();
      }
    }
  std::string langFlags;
  this->LocalGenerator
    ->AddLanguageFlags(langFlags, linkLanguage,
                       this->LocalGenerator->ConfigurationName.c_str());
  // remove any language flags that might not work with the
  // particular os
  if(forbiddenFlagVar)
    {
    this->RemoveForbiddenFlags(forbiddenFlagVar,
                               linkLanguage, langFlags);
    }
  vars.LanguageCompileFlags = langFlags.c_str();
  // Expand placeholders in the commands.
  this->LocalGenerator->TargetImplib = targetOutPathImport;
  if(useLinkScript)
    {
    for(std::vector<std::string>::iterator i = link_script_commands.begin();
        i != link_script_commands.end(); ++i)
      {
      this->LocalGenerator->ExpandRuleVariables(*i, vars);
      }
    }
  else
    {
    for(std::vector<std::string>::iterator i = commands.begin();
        i != commands.end(); ++i)
      {
      this->LocalGenerator->ExpandRuleVariables(*i, vars);
      }
    }
  this->LocalGenerator->TargetImplib = "";

  // Optionally convert the build rule to use a script to avoid long
  // command lines in the make shell.
  if(useLinkScript)
    {
    for(std::vector<std::string>::iterator cmd = link_script_commands.begin();
        cmd != link_script_commands.end(); ++cmd)
      {
      // Do not write out empty commands or commands beginning in the
      // shell no-op ":".
      if(!cmd->empty() && (*cmd)[0] != ':')
        {
        (*linkScriptStream) << *cmd << "\n";
        }
      }
    }

  // Write the build rule.
  this->LocalGenerator->WriteMakeRule(*this->BuildFileStream, 0,
                                      targetFullPathReal.c_str(),
                                      depends, commands, false);

  // Some targets have more than one output file.  Create rules to
  // drive the build if any extra outputs are missing.
  std::vector<std::string> extraOutputs;
  if(targetNameSO != targetNameReal)
    {
    this->GenerateExtraOutput(targetFullPathSO.c_str(),
                              targetFullPathReal.c_str());
    }
  if(targetName != targetNameSO &&
     targetName != targetNameReal)
    {
    this->GenerateExtraOutput(targetFullPath.c_str(),
                              targetFullPathReal.c_str());
    }

  // Write the main driver rule to build everything in this target.
  this->WriteTargetDriverRule(targetFullPath.c_str(), relink);

  // Clean all the possible library names and symlinks.
  this->CleanFiles.insert(this->CleanFiles.end(),
                          libCleanFiles.begin(),libCleanFiles.end());
}