y is set), it will appear in the generated buildsystem
as a build target much like a target defined by the
<span class="target" id="index-0-command:add_custom_target"></span><a class="reference internal" href="add_custom_target.html#command:add_custom_target" title="add_custom_target"><code class="xref cmake cmake-command docutils literal notranslate"><span class="pre">add_custom_target()</span></code></a> command.  It does not compile any sources,
but does contain build rules for custom commands created by