title: How to set warning level in CMake?
body: <p>How to set the <strong>warning level</strong> for a <em>project</em> (not the whole solution) using <strong>CMake</strong>? Should work on <em>Visual Studio</em> and <em>GCC</em>.</p>
  
  <p>I found various options but most seem either not to work or are not consistent with the documentation.</p>