From Tamron:
Dear users and potential purchasers of Tamron interchangeable lenses.
Thank you for using Tamron products and for your continuous support.
We would like to announce that we have clarified compatibility in general operations(*1) of following Tamron Di & Di II lenses on Canon EOS RP, which was newly released on March 14, 2019, with Canon "Mount Adapter EF-EOS R".
(*1) Defined to work on existing DSLR cameras
Compatible models (for Canon) for general operations (*2)
(*2) With the latest F/W version. Regarding the F/W update, please visit here.
(*3) Regarding the update service, please visit here.
Lens Update Service Information
For other models, once we confirm the compatibility with Canon EOS R series and Canon adapter, we will announce the models sequentially at our support website. We are sorry to keep you waiting, and also ask for your understanding of the situation.