Improve error message when export encounters non-local input (#106403)
Previously, you would get an error like
```
Dynamo input and output is a strict subset of traced input/output
```
now you get
```
Cannot export model which references tensors that are neither
buffers/parameters/constants nor are direct inputs. For each tensor, if you'd
like this tensor to be an explicit input, add it as a dummy argument
to the top-level model definition you are exporting; if you would
like its value to be embedded as an exported constant, wrap its access
in a function marked with @assume_constant_result.
G['bulbous_bouffant'], accessed at:
File "test_export.py", line N, in f
return bulbous_bouffant + y
```
This doesn't handle outputs, I'm going to hit that next.
Signed-off-by: Edward Z. Yang <ezyang@meta.com>
Pull Request resolved: https://github.com/pytorch/pytorch/pull/106403
Approved by: https://github.com/tugsbayasgalan
