stringapi: Use strings for AddString methods

It gets turned into a string anyways, so pass them in.

Source/cmCommandArgumentParserHelper.cxx

@@ -49,14 +49,14 @@ void cmCommandArgumentParserHelper::SetLineFile(long line, const char* file)
   this->FileName = file;
 }
 
-char* cmCommandArgumentParserHelper::AddString(const char* str)
+char* cmCommandArgumentParserHelper::AddString(const std::string& str)
 {
-  if ( !str || !*str )
+  if ( str.empty() )
     {
     return this->EmptyVariable;
     }
-  char* stVal = new char[strlen(str)+1];
-  strcpy(stVal, str);
+  char* stVal = new char[str.size()+1];
+  strcpy(stVal, str.c_str());
   this->Variables.push_back(stVal);
   return stVal;
 }
@@ -153,7 +153,7 @@ char* cmCommandArgumentParserHelper::ExpandVariable(const char* var)
     {
     return this->AddString(cmSystemTools::EscapeQuotes(value).c_str());
     }
-  return this->AddString(value);
+  return this->AddString(value ? value : "");
 }
 
 char* cmCommandArgumentParserHelper::ExpandVariableForAt(const char* var)
@@ -166,7 +166,7 @@ char* cmCommandArgumentParserHelper::ExpandVariableForAt(const char* var)
     // then return an empty string
     if(!ret && this->RemoveEmpty)
       {
-      return this->AddString(ret);
+      return this->AddString("");
       }
     // if the ret was not 0, then return it
     if(ret)

Source/cmCommandArgumentParserHelper.h

@@ -86,7 +86,7 @@ private:
   void Print(const char* place, const char* str);
   void SafePrintMissing(const char* str, int line, int cnt);
 
-  char* AddString(const char* str);
+  char* AddString(const std::string& str);
 
   void CleanupParser();
   void SetError(std::string const& msg);

Source/cmGlobalXCodeGenerator.cxx

@@ -613,7 +613,7 @@ cmGlobalXCodeGenerator::CreateObject(cmXCodeObject::Type type)
 
 //----------------------------------------------------------------------------
 cmXCodeObject*
-cmGlobalXCodeGenerator::CreateString(const char* s)
+cmGlobalXCodeGenerator::CreateString(const std::string& s)
 {
   cmXCodeObject* obj = this->CreateObject(cmXCodeObject::STRING);
   obj->SetString(s);

Source/cmGlobalXCodeGenerator.h

@@ -135,7 +135,7 @@ private:
   // correctly.  All objects created are stored in this->XCodeObjects.
   cmXCodeObject* CreateObject(cmXCodeObject::PBXType ptype);
   cmXCodeObject* CreateObject(cmXCodeObject::Type type);
-  cmXCodeObject* CreateString(const char* s);
+  cmXCodeObject* CreateString(const std::string& s);
   cmXCodeObject* CreateObjectReference(cmXCodeObject*);
   cmXCodeObject* CreateXCodeTarget(cmTarget& target,
                                    cmXCodeObject* buildPhases);

Source/cmXCodeObject.cxx

@@ -266,7 +266,7 @@ void cmXCodeObject::PrintString(std::ostream& os) const
 }
 
 //----------------------------------------------------------------------------
-void cmXCodeObject::SetString(const char* s)
+void cmXCodeObject::SetString(const std::string& s)
 {
   this->String = s;
 }

Source/cmXCodeObject.h

@@ -37,7 +37,7 @@ public:
   Type GetType() { return this->TypeValue;}
   PBXType GetIsA() { return this->IsA;}
 
-  void SetString(const char* s);
+  void SetString(const std::string& s);
   const char* GetString()
     {
       return this->String.c_str();