cmake/Source/cmCoreTryCompile.cxx

/*============================================================================
  CMake - Cross Platform Makefile Generator
  Copyright 2000-2011 Kitware, Inc., Insight Software Consortium

  Distributed under the OSI-approved BSD License (the "License");
  see accompanying file Copyright.txt for details.

  This software is distributed WITHOUT ANY WARRANTY; without even the
  implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  See the License for more information.
============================================================================*/
#include "cmCoreTryCompile.h"
#include "cmake.h"
#include "cmOutputConverter.h"
#include "cmGlobalGenerator.h"
#include "cmAlgorithms.h"
#include "cmExportTryCompileFileGenerator.h"
#include <cmsys/Directory.hxx>

#include <assert.h>

int cmCoreTryCompile::TryCompileCode(std::vector<std::string> const& argv)
{
  this->BinaryDirectory = argv[1].c_str();
  this->OutputFile = "";
  // which signature were we called with ?
  this->SrcFileSignature = true;

  const char* sourceDirectory = argv[2].c_str();
  const char* projectName = 0;
  std::string targetName;
  std::vector<std::string> cmakeFlags(1, "CMAKE_FLAGS"); // fake argv[0]
  std::vector<std::string> compileDefs;
  std::string outputVariable;
  std::string copyFile;
  std::string copyFileError;
  std::vector<cmTarget const*> targets;
  std::string libsToLink = " ";
  bool useOldLinkLibs = true;
  char targetNameBuf[64];
  bool didOutputVariable = false;
  bool didCopyFile = false;
  bool didCopyFileError = false;
  bool useSources = argv[2] == "SOURCES";
  std::vector<std::string> sources;

  enum Doing { DoingNone, DoingCMakeFlags, DoingCompileDefinitions,
               DoingLinkLibraries, DoingOutputVariable, DoingCopyFile,
               DoingCopyFileError, DoingSources };
  Doing doing = useSources? DoingSources : DoingNone;
  for(size_t i=3; i < argv.size(); ++i)
    {
    if(argv[i] == "CMAKE_FLAGS")
      {
      doing = DoingCMakeFlags;
      }
    else if(argv[i] == "COMPILE_DEFINITIONS")
      {
      doing = DoingCompileDefinitions;
      }
    else if(argv[i] == "LINK_LIBRARIES")
      {
      doing = DoingLinkLibraries;
      useOldLinkLibs = false;
      }
    else if(argv[i] == "OUTPUT_VARIABLE")
      {
      doing = DoingOutputVariable;
      didOutputVariable = true;
      }
    else if(argv[i] == "COPY_FILE")
      {
      doing = DoingCopyFile;
      didCopyFile = true;
      }
    else if(argv[i] == "COPY_FILE_ERROR")
      {
      doing = DoingCopyFileError;
      didCopyFileError = true;
      }
    else if(doing == DoingCMakeFlags)
      {
      cmakeFlags.push_back(argv[i]);
      }
    else if(doing == DoingCompileDefinitions)
      {
      compileDefs.push_back(argv[i]);
      }
    else if(doing == DoingLinkLibraries)
      {
      libsToLink += "\"" + cmSystemTools::TrimWhitespace(argv[i]) + "\" ";
      if(cmTarget *tgt = this->Makefile->FindTargetToUse(argv[i]))
        {
        switch(tgt->GetType())
          {
          case cmTarget::SHARED_LIBRARY:
          case cmTarget::STATIC_LIBRARY:
          case cmTarget::INTERFACE_LIBRARY:
          case cmTarget::UNKNOWN_LIBRARY:
            break;
          case cmTarget::EXECUTABLE:
            if (tgt->IsExecutableWithExports())
              {
              break;
              }
          default:
            this->Makefile->IssueMessage(cmake::FATAL_ERROR,
              "Only libraries may be used as try_compile or try_run IMPORTED "
              "LINK_LIBRARIES.  Got " + std::string(tgt->GetName()) + " of "
              "type " + tgt->GetTargetTypeName(tgt->GetType()) + ".");
            return -1;
          }
        if (tgt->IsImported())
          {
          targets.push_back(tgt);
          }
        }
      }
    else if(doing == DoingOutputVariable)
      {
      outputVariable = argv[i].c_str();
      doing = DoingNone;
      }
    else if(doing == DoingCopyFile)
      {
      copyFile = argv[i].c_str();
      doing = DoingNone;
      }
    else if(doing == DoingCopyFileError)
      {
      copyFileError = argv[i].c_str();
      doing = DoingNone;
      }
    else if(doing == DoingSources)
      {
      sources.push_back(argv[i]);
      }
    else if(i == 3)
      {
      this->SrcFileSignature = false;
      projectName = argv[i].c_str();
      }
    else if(i == 4 && !this->SrcFileSignature)
      {
      targetName = argv[i].c_str();
      }
    else
      {
      std::ostringstream m;
      m << "try_compile given unknown argument \"" << argv[i] << "\".";
      this->Makefile->IssueMessage(cmake::AUTHOR_WARNING, m.str());
      }
    }

  if(didCopyFile && copyFile.empty())
    {
    this->Makefile->IssueMessage(cmake::FATAL_ERROR,
      "COPY_FILE must be followed by a file path");
    return -1;
    }

  if(didCopyFileError && copyFileError.empty())
    {
    this->Makefile->IssueMessage(cmake::FATAL_ERROR,
      "COPY_FILE_ERROR must be followed by a variable name");
    return -1;
    }

  if(didCopyFileError && !didCopyFile)
    {
    this->Makefile->IssueMessage(cmake::FATAL_ERROR,
      "COPY_FILE_ERROR may be used only with COPY_FILE");
    return -1;
    }

  if(didOutputVariable && outputVariable.empty())
    {
    this->Makefile->IssueMessage(cmake::FATAL_ERROR,
      "OUTPUT_VARIABLE must be followed by a variable name");
    return -1;
    }

  if(useSources && sources.empty())
    {
    this->Makefile->IssueMessage(cmake::FATAL_ERROR,
      "SOURCES must be followed by at least one source file");
    return -1;
    }

  // compute the binary dir when TRY_COMPILE is called with a src file
  // signature
  if (this->SrcFileSignature)
    {
    this->BinaryDirectory += cmake::GetCMakeFilesDirectory();
    this->BinaryDirectory += "/CMakeTmp";
    }
  else
    {
    // only valid for srcfile signatures
    if (!compileDefs.empty())
      {
      this->Makefile->IssueMessage(cmake::FATAL_ERROR,
        "COMPILE_DEFINITIONS specified on a srcdir type TRY_COMPILE");
      return -1;
      }
    if (!copyFile.empty())
      {
      this->Makefile->IssueMessage(cmake::FATAL_ERROR,
        "COPY_FILE specified on a srcdir type TRY_COMPILE");
      return -1;
      }
    }
  // make sure the binary directory exists
  cmSystemTools::MakeDirectory(this->BinaryDirectory.c_str());

  // do not allow recursive try Compiles
  if (this->BinaryDirectory == this->Makefile->GetHomeOutputDirectory())
    {
    std::ostringstream e;
    e << "Attempt at a recursive or nested TRY_COMPILE in directory\n"
      << "  " << this->BinaryDirectory << "\n";
    this->Makefile->IssueMessage(cmake::FATAL_ERROR, e.str());
    return -1;
    }

  std::string outFileName = this->BinaryDirectory + "/CMakeLists.txt";
  // which signature are we using? If we are using var srcfile bindir
  if (this->SrcFileSignature)
    {
    // remove any CMakeCache.txt files so we will have a clean test
    std::string ccFile = this->BinaryDirectory + "/CMakeCache.txt";
    cmSystemTools::RemoveFile(ccFile);

    // Choose sources.
    if(!useSources)
      {
      sources.push_back(argv[2]);
      }

    // Detect languages to enable.
    cmGlobalGenerator* gg = this->Makefile->GetGlobalGenerator();
    std::set<std::string> testLangs;
    for(std::vector<std::string>::iterator si = sources.begin();
        si != sources.end(); ++si)
      {
      std::string ext = cmSystemTools::GetFilenameLastExtension(*si);
      std::string lang = gg->GetLanguageFromExtension(ext.c_str());
      if(!lang.empty())
        {
        testLangs.insert(lang);
        }
      else
        {
        std::ostringstream err;
        err << "Unknown extension \"" << ext << "\" for file\n"
            << "  " << *si << "\n"
            << "try_compile() works only for enabled languages.  "
            << "Currently these are:\n  ";
        std::vector<std::string> langs;
        gg->GetEnabledLanguages(langs);
        err << cmJoin(langs, " ");
        err << "\nSee project() command to enable other languages.";
        this->Makefile->IssueMessage(cmake::FATAL_ERROR, err.str());
        return -1;
        }
      }

    // we need to create a directory and CMakeLists file etc...
    // first create the directories
    sourceDirectory = this->BinaryDirectory.c_str();

    // now create a CMakeLists.txt file in that directory
    FILE *fout = cmsys::SystemTools::Fopen(outFileName,"w");
    if (!fout)
      {
      std::ostringstream e;
      e << "Failed to open\n"
        << "  " << outFileName << "\n"
        << cmSystemTools::GetLastSystemError();
      this->Makefile->IssueMessage(cmake::FATAL_ERROR, e.str());
      return -1;
      }

    const char* def = this->Makefile->GetDefinition("CMAKE_MODULE_PATH");
    fprintf(fout, "cmake_minimum_required(VERSION %u.%u.%u.%u)\n",
            cmVersion::GetMajorVersion(), cmVersion::GetMinorVersion(),
            cmVersion::GetPatchVersion(), cmVersion::GetTweakVersion());
    if(def)
      {
      fprintf(fout, "set(CMAKE_MODULE_PATH \"%s\")\n", def);
      }

    std::string projectLangs;
    for(std::set<std::string>::iterator li = testLangs.begin();
        li != testLangs.end(); ++li)
      {
      projectLangs += " " + *li;
      std::string rulesOverrideBase = "CMAKE_USER_MAKE_RULES_OVERRIDE";
      std::string rulesOverrideLang = rulesOverrideBase + "_" + *li;
      if(const char* rulesOverridePath =
         this->Makefile->GetDefinition(rulesOverrideLang))
        {
        fprintf(fout, "set(%s \"%s\")\n",
                rulesOverrideLang.c_str(), rulesOverridePath);
        }
      else if(const char* rulesOverridePath2 =
              this->Makefile->GetDefinition(rulesOverrideBase))
        {
        fprintf(fout, "set(%s \"%s\")\n",
                rulesOverrideBase.c_str(), rulesOverridePath2);
        }
      }
    fprintf(fout, "project(CMAKE_TRY_COMPILE%s)\n", projectLangs.c_str());
    fprintf(fout, "set(CMAKE_VERBOSE_MAKEFILE 1)\n");
    for(std::set<std::string>::iterator li = testLangs.begin();
        li != testLangs.end(); ++li)
      {
      std::string langFlags = "CMAKE_" + *li + "_FLAGS";
      const char* flags = this->Makefile->GetDefinition(langFlags);
      fprintf(fout, "set(CMAKE_%s_FLAGS %s)\n", li->c_str(),
              cmOutputConverter::EscapeForCMake(flags?flags:"").c_str());
      fprintf(fout, "set(CMAKE_%s_FLAGS \"${CMAKE_%s_FLAGS}"
              " ${COMPILE_DEFINITIONS}\")\n", li->c_str(), li->c_str());
      }
    switch(this->Makefile->GetPolicyStatus(cmPolicies::CMP0056))
      {
      case cmPolicies::WARN:
        if(this->Makefile->PolicyOptionalWarningEnabled(
             "CMAKE_POLICY_WARNING_CMP0056"))
          {
          std::ostringstream w;
          w << cmPolicies::GetPolicyWarning(cmPolicies::CMP0056) << "\n"
            "For compatibility with older versions of CMake, try_compile "
            "is not honoring caller link flags (e.g. CMAKE_EXE_LINKER_FLAGS) "
            "in the test project."
            ;
          this->Makefile->IssueMessage(cmake::AUTHOR_WARNING, w.str());
          }
      case cmPolicies::OLD:
        // OLD behavior is to do nothing.
        break;
      case cmPolicies::REQUIRED_IF_USED:
      case cmPolicies::REQUIRED_ALWAYS:
        this->Makefile->IssueMessage(
          cmake::FATAL_ERROR,
          cmPolicies::GetRequiredPolicyError(cmPolicies::CMP0056)
          );
      case cmPolicies::NEW:
        // NEW behavior is to pass linker flags.
        {
        const char* exeLinkFlags =
          this->Makefile->GetDefinition("CMAKE_EXE_LINKER_FLAGS");
        fprintf(fout, "set(CMAKE_EXE_LINKER_FLAGS %s)\n",
                cmOutputConverter::EscapeForCMake(
                    exeLinkFlags ? exeLinkFlags : "").c_str());
        } break;
      }
    fprintf(fout, "set(CMAKE_EXE_LINKER_FLAGS \"${CMAKE_EXE_LINKER_FLAGS}"
            " ${EXE_LINKER_FLAGS}\")\n");
    fprintf(fout, "include_directories(${INCLUDE_DIRECTORIES})\n");
    fprintf(fout, "set(CMAKE_SUPPRESS_REGENERATION 1)\n");
    fprintf(fout, "link_directories(${LINK_DIRECTORIES})\n");
    // handle any compile flags we need to pass on
    if (!compileDefs.empty())
      {
      fprintf(fout, "add_definitions(%s)\n", cmJoin(compileDefs, " ").c_str());
      }

    /* Use a random file name to avoid rapid creation and deletion
       of the same executable name (some filesystems fail on that).  */
    sprintf(targetNameBuf, "cmTC_%05x",
            cmSystemTools::RandomSeed() & 0xFFFFF);
    targetName = targetNameBuf;

    if (!targets.empty())
      {
      std::string fname = "/" + std::string(targetName) + "Targets.cmake";
      cmExportTryCompileFileGenerator tcfg(gg);
      tcfg.SetExportFile((this->BinaryDirectory + fname).c_str());
      tcfg.SetExports(targets);
      tcfg.SetConfig(this->Makefile->GetSafeDefinition(
                                          "CMAKE_TRY_COMPILE_CONFIGURATION"));

      if(!tcfg.GenerateImportFile())
        {
        this->Makefile->IssueMessage(cmake::FATAL_ERROR,
                                     "could not write export file.");
        fclose(fout);
        return -1;
        }
      fprintf(fout,
              "\ninclude(\"${CMAKE_CURRENT_LIST_DIR}/%s\")\n\n",
              fname.c_str());
      }

    /* for the TRY_COMPILEs we want to be able to specify the architecture.
      So the user can set CMAKE_OSX_ARCHITECTURES to i386;ppc and then set
      CMAKE_TRY_COMPILE_OSX_ARCHITECTURES first to i386 and then to ppc to
      have the tests run for each specific architecture. Since
      cmLocalGenerator doesn't allow building for "the other"
      architecture only via CMAKE_OSX_ARCHITECTURES.
      */
    if(this->Makefile->GetDefinition("CMAKE_TRY_COMPILE_OSX_ARCHITECTURES")!=0)
      {
      std::string flag="-DCMAKE_OSX_ARCHITECTURES=";
      flag += this->Makefile->GetSafeDefinition(
                                        "CMAKE_TRY_COMPILE_OSX_ARCHITECTURES");
      cmakeFlags.push_back(flag);
      }
    else if (this->Makefile->GetDefinition("CMAKE_OSX_ARCHITECTURES")!=0)
      {
      std::string flag="-DCMAKE_OSX_ARCHITECTURES=";
      flag += this->Makefile->GetSafeDefinition("CMAKE_OSX_ARCHITECTURES");
      cmakeFlags.push_back(flag);
      }
    /* on APPLE also pass CMAKE_OSX_SYSROOT to the try_compile */
    if(this->Makefile->GetDefinition("CMAKE_OSX_SYSROOT")!=0)
      {
      std::string flag="-DCMAKE_OSX_SYSROOT=";
      flag += this->Makefile->GetSafeDefinition("CMAKE_OSX_SYSROOT");
      cmakeFlags.push_back(flag);
      }
    /* on APPLE also pass CMAKE_OSX_DEPLOYMENT_TARGET to the try_compile */
    if(this->Makefile->GetDefinition("CMAKE_OSX_DEPLOYMENT_TARGET")!=0)
      {
      std::string flag="-DCMAKE_OSX_DEPLOYMENT_TARGET=";
      flag += this->Makefile->GetSafeDefinition("CMAKE_OSX_DEPLOYMENT_TARGET");
      cmakeFlags.push_back(flag);
      }
    if (const char *cxxDef
              = this->Makefile->GetDefinition("CMAKE_CXX_COMPILER_TARGET"))
      {
      std::string flag="-DCMAKE_CXX_COMPILER_TARGET=";
      flag += cxxDef;
      cmakeFlags.push_back(flag);
      }
    if (const char *cDef
                = this->Makefile->GetDefinition("CMAKE_C_COMPILER_TARGET"))
      {
      std::string flag="-DCMAKE_C_COMPILER_TARGET=";
      flag += cDef;
      cmakeFlags.push_back(flag);
      }
    if (const char *tcxxDef = this->Makefile->GetDefinition(
                                  "CMAKE_CXX_COMPILER_EXTERNAL_TOOLCHAIN"))
      {
      std::string flag="-DCMAKE_CXX_COMPILER_EXTERNAL_TOOLCHAIN=";
      flag += tcxxDef;
      cmakeFlags.push_back(flag);
      }
    if (const char *tcDef = this->Makefile->GetDefinition(
                                    "CMAKE_C_COMPILER_EXTERNAL_TOOLCHAIN"))
      {
      std::string flag="-DCMAKE_C_COMPILER_EXTERNAL_TOOLCHAIN=";
      flag += tcDef;
      cmakeFlags.push_back(flag);
      }
    if (const char *rootDef
              = this->Makefile->GetDefinition("CMAKE_SYSROOT"))
      {
      std::string flag="-DCMAKE_SYSROOT=";
      flag += rootDef;
      cmakeFlags.push_back(flag);
      }
    if(this->Makefile->GetDefinition("CMAKE_POSITION_INDEPENDENT_CODE")!=0)
      {
      fprintf(fout, "set(CMAKE_POSITION_INDEPENDENT_CODE \"ON\")\n");
      }
    if (const char *lssDef = this->Makefile->GetDefinition(
        "CMAKE_LINK_SEARCH_START_STATIC"))
      {
      fprintf(fout, "set(CMAKE_LINK_SEARCH_START_STATIC \"%s\")\n", lssDef);
      }
    if (const char *lssDef = this->Makefile->GetDefinition(
        "CMAKE_LINK_SEARCH_END_STATIC"))
      {
      fprintf(fout, "set(CMAKE_LINK_SEARCH_END_STATIC \"%s\")\n", lssDef);
      }

    /* Set the appropriate policy information for ENABLE_EXPORTS */
    fprintf(fout, "cmake_policy(SET CMP0065 %s)\n",
       this->Makefile->GetPolicyStatus(cmPolicies::CMP0065) ==
         cmPolicies::NEW ? "NEW" : "OLD");
    if(const char *ee = this->Makefile->GetDefinition(
        "CMAKE_ENABLE_EXPORTS"))
      {
      fprintf(fout, "set(CMAKE_ENABLE_EXPORTS %s)\n", ee);
      }

    /* Put the executable at a known location (for COPY_FILE).  */
    fprintf(fout, "set(CMAKE_RUNTIME_OUTPUT_DIRECTORY \"%s\")\n",
            this->BinaryDirectory.c_str());
    /* Create the actual executable.  */
    fprintf(fout, "add_executable(%s", targetName.c_str());
    for(std::vector<std::string>::iterator si = sources.begin();
        si != sources.end(); ++si)
      {
      fprintf(fout, " \"%s\"", si->c_str());

      // Add dependencies on any non-temporary sources.
      if(si->find("CMakeTmp") == si->npos)
        {
        this->Makefile->AddCMakeDependFile(*si);
        }
      }
    fprintf(fout, ")\n");
    if (useOldLinkLibs)
      {
      fprintf(fout,
              "target_link_libraries(%s ${LINK_LIBRARIES})\n",
              targetName.c_str());
      }
    else
      {
      fprintf(fout, "target_link_libraries(%s %s)\n",
              targetName.c_str(),
              libsToLink.c_str());
      }
    fclose(fout);
    projectName = "CMAKE_TRY_COMPILE";
    }

  bool erroroc = cmSystemTools::GetErrorOccuredFlag();
  cmSystemTools::ResetErrorOccuredFlag();
  std::string output;
  // actually do the try compile now that everything is setup
  int res = this->Makefile->TryCompile(sourceDirectory,
                                       this->BinaryDirectory,
                                       projectName,
                                       targetName,
                                       this->SrcFileSignature,
                                       &cmakeFlags,
                                       output);
  if ( erroroc )
    {
    cmSystemTools::SetErrorOccured();
    }

  // set the result var to the return value to indicate success or failure
  this->Makefile->AddCacheDefinition(argv[0],
                                     (res == 0 ? "TRUE" : "FALSE"),
                                     "Result of TRY_COMPILE",
                                     cmState::INTERNAL);

  if (!outputVariable.empty())
    {
    this->Makefile->AddDefinition(outputVariable, output.c_str());
    }

  if (this->SrcFileSignature)
    {
    std::string copyFileErrorMessage;
    this->FindOutputFile(targetName);

    if ((res==0) && !copyFile.empty())
      {
      if(this->OutputFile.empty() ||
         !cmSystemTools::CopyFileAlways(this->OutputFile,
                                        copyFile))
        {
        std::ostringstream emsg;
        emsg << "Cannot copy output executable\n"
             << "  '" << this->OutputFile << "'\n"
             << "to destination specified by COPY_FILE:\n"
             << "  '" << copyFile << "'\n";
        if(!this->FindErrorMessage.empty())
          {
          emsg << this->FindErrorMessage.c_str();
          }
        if(copyFileError.empty())
          {
          this->Makefile->IssueMessage(cmake::FATAL_ERROR, emsg.str());
          return -1;
          }
        else
          {
          copyFileErrorMessage = emsg.str();
          }
        }
      }

    if(!copyFileError.empty())
      {
      this->Makefile->AddDefinition(copyFileError,
                                    copyFileErrorMessage.c_str());
      }
    }
  return res;
}

void cmCoreTryCompile::CleanupFiles(const char* binDir)
{
  if ( !binDir )
    {
    return;
    }

  std::string bdir = binDir;
  if(bdir.find("CMakeTmp") == std::string::npos)
    {
    cmSystemTools::Error(
      "TRY_COMPILE attempt to remove -rf directory that does not contain "
      "CMakeTmp:", binDir);
    return;
    }

  cmsys::Directory dir;
  dir.Load(binDir);
  size_t fileNum;
  std::set<std::string> deletedFiles;
  for (fileNum = 0; fileNum <  dir.GetNumberOfFiles(); ++fileNum)
    {
    if (strcmp(dir.GetFile(static_cast<unsigned long>(fileNum)),".") &&
        strcmp(dir.GetFile(static_cast<unsigned long>(fileNum)),".."))
      {

      if(deletedFiles.find( dir.GetFile(static_cast<unsigned long>(fileNum)))
         == deletedFiles.end())
        {
        deletedFiles.insert(dir.GetFile(static_cast<unsigned long>(fileNum)));
        std::string fullPath = binDir;
        fullPath += "/";
        fullPath += dir.GetFile(static_cast<unsigned long>(fileNum));
        if(cmSystemTools::FileIsDirectory(fullPath))
          {
          this->CleanupFiles(fullPath.c_str());
          cmSystemTools::RemoveADirectory(fullPath);
          }
        else
          {
#ifdef _WIN32
          // Sometimes anti-virus software hangs on to new files so we
          // cannot delete them immediately.  Try a few times.
          cmSystemTools::WindowsFileRetry retry =
            cmSystemTools::GetWindowsFileRetry();
          while(!cmSystemTools::RemoveFile(fullPath.c_str()) &&
                --retry.Count && cmSystemTools::FileExists(fullPath.c_str()))
            {
            cmSystemTools::Delay(retry.Delay);
            }
          if(retry.Count == 0)
#else
          if(!cmSystemTools::RemoveFile(fullPath))
#endif
            {
            std::string m = "Remove failed on file: " + fullPath;
            cmSystemTools::ReportLastSystemError(m.c_str());
            }
          }
        }
      }
    }
}

void cmCoreTryCompile::FindOutputFile(const std::string& targetName)
{
  this->FindErrorMessage = "";
  this->OutputFile = "";
  std::string tmpOutputFile = "/";
  tmpOutputFile += targetName;
  tmpOutputFile +=this->Makefile->GetSafeDefinition("CMAKE_EXECUTABLE_SUFFIX");

  // a list of directories where to search for the compilation result
  // at first directly in the binary dir
  std::vector<std::string> searchDirs;
  searchDirs.push_back("");

  const char* config = this->Makefile->GetDefinition(
                                            "CMAKE_TRY_COMPILE_CONFIGURATION");
  // if a config was specified try that first
  if (config && config[0])
    {
    std::string tmp = "/";
    tmp += config;
    searchDirs.push_back(tmp);
    }
  searchDirs.push_back("/Debug");
#if defined(__APPLE__)
  std::string app = "/Debug/" + targetName + ".app";
  searchDirs.push_back(app);
#endif
  searchDirs.push_back("/Development");

  for(std::vector<std::string>::const_iterator it = searchDirs.begin();
      it != searchDirs.end();
      ++it)
    {
    std::string command = this->BinaryDirectory;
    command += *it;
    command += tmpOutputFile;
    if(cmSystemTools::FileExists(command.c_str()))
      {
      this->OutputFile = cmSystemTools::CollapseFullPath(command);
      return;
      }
    }

  std::ostringstream emsg;
  emsg << "Unable to find the executable at any of:\n";
  emsg << cmWrap("  " + this->BinaryDirectory,
                 searchDirs,
                 tmpOutputFile, "\n") << "\n";
  this->FindErrorMessage = emsg.str();
  return;
}