Add support for overloaded functions (#15556)
Summary:
This PR adds support for overloaded functions as a step toward adding rnn modules to the JIT standard library.
Possible overloads must be manually specified, and when resolving the overload it chooses by the first one that passes the schema matching logic. The structure is very similar to boolean dispatch in #14425. The overload will only work on weak modules.
In order to avoid supporting overloaded methods in Python to match the JIT execution, the current setup offloads that work to the user. In the test added in `test_jit.py`, two methods are used to overload the `forward` method. In order to call `forward` outside the JIT, a Python-only `forward` that does the right argument type switching must also be provided.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/15556
Differential Revision: D13576348
Pulled By: driazati
fbshipit-source-id: 7d3bdd4ee5a6088cc20c92f26a696d1ee5b9204b
