BUG: a fix for constant recomputing of depends

Source/cmDepends.cxx

@@ -48,6 +48,11 @@ void cmDepends::SetTargetFile(const char* dir, const char* targetFile,
   m_DependsMarkFile += m_TargetFile;
   m_DependsMakeFile += makeExt;
   m_DependsMarkFile += markExt;
+
+  if (!m_CompileDirectory.size())
+    {
+    m_CompileDirectory = dir;
+    }
 }
 
 
@@ -79,12 +84,12 @@ void cmDepends::Check()
 {
   // Dependency checks must be done in proper working directory.
   std::string oldcwd = ".";
-  if(m_Directory != ".")
+  if(m_CompileDirectory != ".")
     {
     // Get the CWD but do not call CollapseFullPath because
     // we only need it to cd back, and the form does not matter
     oldcwd = cmSystemTools::GetCurrentWorkingDirectory(false);
-    cmSystemTools::ChangeDirectory(m_Directory.c_str());
+    cmSystemTools::ChangeDirectory(m_CompileDirectory.c_str());
     }
 
   // Check whether dependencies must be regenerated.

Source/cmDepends.h

@@ -37,6 +37,9 @@ public:
   void SetTargetFile(const char* dir, const char* targetFile, 
                      const char *markExt, const char *makeExt);
 
+  /** at what level will the compile be done from */
+  void SetCompileDirectory(const char *dir) {m_CompileDirectory = dir;};
+    
   /** should this be verbose in its output */
   void SetVerbose(bool verb) { m_Verbose = verb; }
     
@@ -71,6 +74,7 @@ protected:
 
   // The directory in which the build rule for the target file is executed.
   std::string m_Directory;
+  std::string m_CompileDirectory;
 
   // The name of the target file for which dependencies are maintained.
   std::string m_TargetFile;

Source/cmLocalUnixMakefileGenerator3.cxx

@@ -2697,6 +2697,7 @@ cmLocalUnixMakefileGenerator3::GetDependsChecker(const std::string& lang,
   if (ret)
     {
     ret->SetTargetFile(dir, objFile, ".depend",".build.depend.make");
+    ret->SetCompileDirectory(m_Makefile->GetHomeOutputDirectory());
     ret->SetVerbose(verbose);
     }
   return ret;
@@ -2958,8 +2959,7 @@ void cmLocalUnixMakefileGenerator3::CheckDependencies(cmMakefile* mf,
         {
         // Construct a checker for the given language.
         std::auto_ptr<cmDepends>
-          checker(cmLocalUnixMakefileGenerator3
+          checker(this->GetDependsChecker(*l, ".", f->c_str(), verbose));
-                  ::GetDependsChecker(*l, ".", f->c_str(), verbose));
         if(checker.get())
           {
           checker->Check();

Source/cmLocalUnixMakefileGenerator3.h

@@ -215,7 +215,7 @@ protected:
                                std::string& depMarkFile);
 
   // return the appropriate depends checker
-  static cmDepends* GetDependsChecker(const std::string& lang,
+  cmDepends* GetDependsChecker(const std::string& lang,
                                const char* dir,
                                const char* objFile,
                                bool verbose);