 href="../command/add_custom_command.html#command:add_custom_command" title="add_custom_command"><code class="xref cmake cmake-command docutils literal notranslate"><span class="pre">add_custom_command()</span></code></a>
which specified an input to a command.  This was undocumented behavior.
Modern use of CMake associates custom commands with their output, rather
than their input.</p>
<p>The <code class="docutils literal notranslate"><span class="pre">OLD</span></code> behavior for this policy is to allow 