[FX] Fix NoneType annotation in generated code

[jamesr66a]

Stack from ghstack:

• [FX] Fix NoneType annotation in generated code #50777 [FX] Fix NoneType annotation in generated code

Previously, when trying to symbolically trace some Modules that had--for example--Union[Tensor, NoneType] as a parameter, execution would fail because the repr for NoneType doesn't map to any name in Python (NoneType is only directly exposed on the types namespace in Python 3.10+). This change makes it so that NoneType is available in the global namespace and ensures that we do not have any collisions with that name.

Old error:

  File "<eval_with_key_0>", line 3, in <module>
    def forward(self, input : torch.Tensor, offsets : typing.Union[torch.Tensor, NoneType] = None, per_sample_weights : typing.Union[torch.Tensor, NoneType] = None) -> torch.Tensor:
NameError: name 'NoneType' is not defined

Differential Revision: D25966026

[Chillee]

LGTM

[codecov]

Codecov Report

Merging #50777 (b733da1) into gh/jamesr66a/355/base (526659d) will increase coverage by 4.93%.
The diff coverage is 100.00%.

@@                    Coverage Diff                    @@
##           gh/jamesr66a/355/base   #50777      +/-   ##
=========================================================
+ Coverage                  75.74%   80.68%   +4.93%     
=========================================================
  Files                       1913     1913              
  Lines                     208155   208155              
=========================================================
+ Hits                      157666   167945   +10279     
+ Misses                     50489    40210   -10279     

[facebook-github-bot]

@jamesr66a merged this pull request in 5205cc1.