title: Can you assign the value of one union member to another?
body: <p>Consider the following code snippet:</p>
  
  <pre><code>union
  {
     int a;
     float b;
  };
  
  a = /* ... */;
  
  b = a;               // is this UB?
  b = b + something;
  </code></pre>
  
  <p>Is the assignment of one union member to another valid?</p>