Calling macros across crate boundaries has been the source of so many bugs that I am known to write hyperbolic statements like 'death to all macros'. Instead of being so dramatic we could use include! to include a SSOT file that contains the code. Achieves the same aim which is to not have code duplication.

To close this issue please do:

• Find a simple macro from internals
• Deprecate it but do not remove it (either with the attribute if that works or just in the docs). (Do not remove so as to not break the API needlessly).
• Create a file somewhere with the macro code in it (where to put it left to the implementer but please think carefully).
• Use include! in multiple crates to prove this all works.
• Write an issue saying 'Consider removing macro foo right before next breaking release of internals '

Additional notes

See primitives/src/hash_types/ for an example of include! usage.