title: Union of same type in C++
body: <p>Whenever I see examples of union, they are always different types. For example, from MSDN:</p>
  
  <pre><code>// declaring_a_union.cpp
  union DATATYPE    // Declare union type
  {
      char   ch;
      int    i;
      long   l;
      float  f;
      double d;
  } var1;          // Optional declaration of union variable
  
  int main()
  {
  }
  </code></pre>
  
  <p>What happens if I have a union (in this case anonymous, but that shouldn't matter) like this:</p>
  
  <pre><code>union
  {
      float m_1stVar;
      float m_1stVarAlternateName;
  };
  </code></pre>
  
  <p>Regardless of whether this is good practice or not, will this cause any issues?</p>