address compilation warnings

the declspec warning is safe particularly as this is an internal
class not intended to be part of the public API.

IO/Xdmf3/vtkXdmf3ArrayKeeper.h

@@ -34,6 +34,10 @@
 
 class XdmfArray;
 
+#ifdef _MSC_VER
+#pragma warning (push) //save
+#pragma warning (disable: 4251) //needs to have dll-interface to be used by clients of class
+#endif
 class VTKIOXDMF3_EXPORT vtkXdmf3ArrayKeeper
   : public std::map<XdmfArray *, unsigned int>
 {
@@ -67,6 +71,9 @@ public:
 private:
   unsigned int generation;
 };
+#ifdef _MSC_VER
+#pragma warning (pop) //restore
+#endif
 
 #endif //vtkXdmf3ArrayKeeper_h
 // VTK-HeaderTest-Exclude: vtkXdmf3ArrayKeeper.h

IO/Xdmf3/vtkXdmf3ArraySelection.h

@@ -33,6 +33,10 @@
 #include <map> //for superclass template
 #include <string> //for superclass's content type
 
+#ifdef _MSC_VER
+#pragma warning (push) //save
+#pragma warning (disable: 4251) //needs to have dll-interface to be used by clients of class
+#endif
 class VTKIOXDMF3_EXPORT vtkXdmf3ArraySelection
   : public std::map<std::string, bool>
 {
@@ -70,13 +74,14 @@ public:
    */
   const char* GetArrayName(int index);
 
-  //@{
   /**
    * get number of arrays in the set
    */
   int GetNumberOfArrays();
 };
-  //@}
+#ifdef _MSC_VER
+#pragma warning (pop) //restore
+#endif
 
 #endif //# vtkXdmf3ArraySelection_h
 // VTK-HeaderTest-Exclude: vtkXdmf3ArraySelection.h

IO/Xdmf3/vtkXdmf3Writer.cxx

@@ -354,7 +354,7 @@ void vtkXdmf3Writer::WriteDataInternal (vtkInformation* request)
   }
   this->CheckParameters();
   std::string testString(this->FileName);
-  int tempLength = testString.length();
+  size_t tempLength = testString.length();
   testString = testString.substr(0, (tempLength - 4));
   std::string choppedFileName = testString;
   if (this->InitWriters == true)