Instead of using the Driver in Ppxlib, use Ppx_deriving. A deriver gets passed a module path and options, and is invoked only when the particular deriving flag is used. That makes a lot of code we had unnecessary.

Small loss:i f a module version name is wrong, like Vx instead of V1, we don't have the location to highlight in Merlin.

I discovered a dune bug others had reported, mentioned in the dune for the tests. Added a VERBOSE flag to the Makefile, allowing confirmation that expected test failures fail for the expected reason.

Checklist:

• Tests were added for the new behavior
• All tests pass (CI will check this if you didn't)
• Serialized types are in stable-versioned modules
• Does this close issues? List them: