title: Cmake --config since version 3.20
body: <p>All the build hierarchy of my project is based on <code>ExternalProject</code> with <code>--config</code> option. A few days ago I updated to cmake 3.20, and now <code>--config</code> is gone:</p>
  <pre><code>$ cmake --config
  CMake Error: Unknown argument --config
  CMake Error: Run 'cmake --help' for all supported options.
  </code></pre>
  <p>while <a href="https://cmake.org/cmake/help/latest/command/build_command.html" rel="nofollow noreferrer">documentation</a> <a href="https://cmake.org/cmake/help/latest/guide/tutorial/index.html" rel="nofollow noreferrer">still advises</a> to use it. <a href="https://cmake.org/cmake/help/latest/release/3.20.html" rel="nofollow noreferrer">Release notes</a> are also silent about the option.</p>
  <p>What should I use instead of <code>--config</code>?</p>