[SO] Modifing local class instance in pure function

[Jesse Phillips]

http://stackoverflow.com/questions/1008803/how-to-use-pure-in-d-2-0

class TestPure
{
string[] msg;
void addMsg( string s )
{
       msg ~= s;
   }
};

pure TestPure run2()
{
   TestPure t = new TestPure();
   t.addMsg("Test");
   t.addMsg("this.");
   return t;
}

This doesn't work and the answer from CyberShodow is that you could thread inside the pure function modifying the class value at the same time. Isn't that still an issue if TestPure was change to an int?