Is there a Canon-Canon speedboster?

[Oller Visuals]

This has probably been brought up before, but wasn't able to google. Is there such a thing as a Canon EF - Canon EF Speedboster?

Ie, FF lenses used onto an optical plane that focuses the entire image area onto an APS-C sensor.

 

[IndyFilmPhreak2013]

Flange depth and mirror interference makes that impossible.

 

[Ebrahim Saadawi]

Only one possible is Ef to Eos-m speedbooster. Would be awesome to make the eos m fullframe.