A new patent showing an optical formula for a new wide angle prime has appeared. The full frame lens in the application is an EF 15mm f/4, while the APS-C optical formula of a EF-M 9. 5mm f/4 shows a shorter backfocus than an EF-S lens and could actually be EF-M.
Japan Patent Application 2018-004726 Canon EF-M Read more. . . . canonrumors.com