Long ago i had this question, and the general answer was as chromatic replied, so i wrote the code that diotalevi points out, first in Data::Dump::Streamer and later moved it to re.pm in core. However the latter is only in the blead perl version and is not yet available in a production release of Perl.

Had chromatic not vetoed my UNIVERSAL::DOES patch it would have been possible to do UNIVERSAL::DOES($rx,'qr//') but he elected to make said function/method essentially useless in the name of OO purity instead. Sad but true. Such is life in open source. :-(