constant output errors (#110472)
When mapping between the original signature of a program and the graph-captured signature of its exported program, we emit errors when we see unexpected original or graph-captured inputs or outputs.
These errors can arise because of various reasons, e.g.:
1. some input or output has been lifted because of mutation
2. some type is not pytree-registered for flattening / unflattening
3. some type cannot be realized with graph operations
(This is probably not an exhaustive list.)
Previously we used to emit errors based on a vanilla id-based membership check between the two sides, mostly anticipating (1) as the reason for errors. But this does not do justice to errors because of (2) or (3).
This PR emits a different error when it finds (3) to be a probable cause. Specifically, it considers only Tensor and Sym* types to be "supported": no other type seems to be realizable by graph operations.
When (2) is a probable cause, we sometimes also hit the same error because we would expect the supported types to show through upon registration. But this kind of error may need some more work in the future.
Differential Revision: [D49885828](https://our.internmc.facebook.com/intern/diff/D49885828/)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/110472
Approved by: https://github.com/ydwu4
