title: GCC C warning "duplicate ‘const’ declaration "
body: <p>Why am I getting </p>
  
  <blockquote>
    <p>duplicate ‘const’ declaration specifier [-Wduplicate-decl-specifier]</p>
  </blockquote>
  
  <p>for this declaration? </p>
  
  <pre><code>extern uint8_t CalculateChecksum(const communicationBlock_t const *messageBlock);
  </code></pre>
  
  <p>Where <code>communicationBlock_t</code> is a struct.</p>
  
  <p>I don't the function to be able to change the structure pointed to by the parameter, nor do I want it to be able to point that parameter elsewhere.</p>
  
  <p>What am I doing wrongly?</p>