title: Compiler Hint: "Inline function '...' has not been expanded..."
body: <p>In a unit I use the function <code>DeleteFile</code> and the compiler outputs a hint:</p>
  
  <blockquote>
    <p>"H2443 Inline function 'DeleteFile' has not been expanded because unit 'Windows' is not specified in USES list"</p>
  </blockquote>
  
  <p>In <code>Uses</code> there is <code>SysUtils</code>, which defines <code>DeleteFile</code> (although internally calling <code>Windows.DeleteFile</code>).</p>
  
  <p>What does this hint mean? If I put <code>Windows</code> into the <code>Uses</code> clause, it's gone, but I would like to understand what it is that bothers the compiler.</p>