Comment by wolvesechoes

Modelica, which is a DSL for modelling DAE systems, has a facility of automated conversions. You can provide a script that automatically modifies user's code then they upgrade to newer version of your lib, or prints the message if automatic migration is not possible.

It is very strange that more mainstream languages do not have such features (and I am not talking about 3rd party tools; in Modelica conversions are part of the language spec).