ppx_fields_conv documentationppx_fields_conv functionsppx_fields_conv.ml differed (ex: a variable would be called one thing when implementing one function but would be called something different when implementing every other function).The iter function generated by ppx_variants_conv and ppx_fields_conv allowed one to give function which returned values of arbitrary types as iter function. This release constraint these functions to return unit.
N.B. the signature generated by the use of @@deriving variants (resp. fields) in interface already constrained the type to unit.
Fields.make_creator to ppx_fields_conv's readme, since it appears to not be all that deprecated.