ENH: Generalize exe implib dir creation for VS

In VS 7,8,9 executable targets we generate a build event to create the
output directory for the import library in case the executable marks
symbols with dllexport (VS forgets to create this directory).  This
generalizes computation of the custom command line to support future use
with other VS versions.

Source/cmLocalVisualStudio7Generator.cxx

@@ -1674,33 +1674,6 @@ void cmLocalVisualStudio7Generator::WriteVCProjEndGroup(std::ostream& fout)
   fout << "\t\t</Filter>\n";
 }
 
-void cmLocalVisualStudio7Generator::MaybeCreateImplibDir(cmTarget& target,
-                                                         const char* config,
-                                                         EventWriter& event)
-{
-  // If an executable exports symbols then VS wants to create an
-  // import library but forgets to create the output directory.
-  if(target.GetType() != cmTarget::EXECUTABLE) { return; }
-  std::string outDir = target.GetDirectory(config, false);
-  std::string impDir = target.GetDirectory(config, true);
-  if(impDir == outDir) { return; }
-
-  // Add a pre-build event to create the directory.
-  cmCustomCommandLine command;
-  command.push_back(this->Makefile->GetRequiredDefinition("CMAKE_COMMAND"));
-  command.push_back("-E");
-  command.push_back("make_directory");
-  command.push_back(impDir);
-  std::vector<std::string> no_output;
-  std::vector<std::string> no_depends;
-  cmCustomCommandLines commands;
-  commands.push_back(command);
-  cmCustomCommand cc(no_output, no_depends, commands, 0, 0);
-  cc.SetEscapeOldStyle(false);
-  cc.SetEscapeAllowMakeVars(true);
-  event.Write(cc);
-}
-
 
 // look for custom rules on a target and collect them together
 void cmLocalVisualStudio7Generator
@@ -1720,7 +1693,12 @@ void cmLocalVisualStudio7Generator
     this->FortranProject? "VFPreBuildEventTool":"VCPreBuildEventTool";
   event.Start(tool);
   event.Write(target.GetPreBuildCommands());
-  this->MaybeCreateImplibDir(target, configName, event);
+  cmsys::auto_ptr<cmCustomCommand> pcc(
+    this->MaybeCreateImplibDir(target, configName));
+  if(pcc.get())
+    {
+    event.Write(*pcc);
+    }
   event.Finish();
 
   // Add pre-link event.

Source/cmLocalVisualStudio7Generator.h

@@ -125,8 +125,6 @@ private:
 
   class EventWriter;
   friend class EventWriter;
-  void MaybeCreateImplibDir(cmTarget& target, const char* config,
-                            EventWriter& event);
 
   cmVS7FlagTable const* ExtraFlagTable;
   std::string ModuleDefinitionFile;

Source/cmLocalVisualStudioGenerator.cxx

@@ -33,6 +33,36 @@ cmLocalVisualStudioGenerator::~cmLocalVisualStudioGenerator()
 {
 }
 
+//----------------------------------------------------------------------------
+cmsys::auto_ptr<cmCustomCommand>
+cmLocalVisualStudioGenerator::MaybeCreateImplibDir(cmTarget& target,
+                                                   const char* config)
+{
+  cmsys::auto_ptr<cmCustomCommand> pcc;
+
+  // If an executable exports symbols then VS wants to create an
+  // import library but forgets to create the output directory.
+  if(target.GetType() != cmTarget::EXECUTABLE) { return pcc; }
+  std::string outDir = target.GetDirectory(config, false);
+  std::string impDir = target.GetDirectory(config, true);
+  if(impDir == outDir) { return pcc; }
+
+  // Add a pre-build event to create the directory.
+  cmCustomCommandLine command;
+  command.push_back(this->Makefile->GetRequiredDefinition("CMAKE_COMMAND"));
+  command.push_back("-E");
+  command.push_back("make_directory");
+  command.push_back(impDir);
+  std::vector<std::string> no_output;
+  std::vector<std::string> no_depends;
+  cmCustomCommandLines commands;
+  commands.push_back(command);
+  pcc.reset(new cmCustomCommand(no_output, no_depends, commands, 0, 0));
+  pcc->SetEscapeOldStyle(false);
+  pcc->SetEscapeAllowMakeVars(true);
+  return pcc;
+}
+
 //----------------------------------------------------------------------------
 bool cmLocalVisualStudioGenerator::SourceFileCompiles(const cmSourceFile* sf)
 {

Source/cmLocalVisualStudioGenerator.h

@@ -19,6 +19,8 @@
 
 #include "cmLocalGenerator.h"
 
+#include <cmsys/auto_ptr.hxx>
+
 class cmSourceFile;
 class cmSourceGroup;
 
@@ -35,6 +37,10 @@ public:
   virtual ~cmLocalVisualStudioGenerator();
 protected:
 
+  /** Construct a custom command to make exe import lib dir.  */
+  cmsys::auto_ptr<cmCustomCommand>
+  MaybeCreateImplibDir(cmTarget& target, const char* config);
+
   /** Construct a script from the given list of command lines.  */
   std::string ConstructScript(const cmCustomCommandLines& commandLines,
                               const char* workingDirectory,