Would it be more acceptable to use a DeprecationWarning? It's not really the right thing because we're not planning to ever actually remove the functionality. But, we've already gone to a lot of trouble to try to show DeprecationWarnings specifically to devs and not end users (hiding them by default, except if the source was the REPL or a test, getting patches into every test framework to handle this, etc.). And the issues here seem to be identical.

Or maybe LintWarning inherits from DeprecationWarning? Or the share a common superclass?