Move default or no default logic into native.argument (#49489)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/49489
Previously, it was done at a use site, but that meant other use
sites don't get the right logic. Pushing it in makes sure everyone
gets it.
I also fixed one case of confusion where defn() was used to define a decl().
If you want to define a declaration with no defaults, say no_default().decl()
which is more direct and will give us code reviewers a clue if you should
have pushed this logic in.
Signed-off-by: Edward Z. Yang <ezyang@fb.com>
Test Plan: Imported from OSS
Reviewed By: smessmer
Differential Revision: D25595407
Pulled By: ezyang
fbshipit-source-id: 89c664f0ed4d95699794a0d3123d54d0f7e4cba4
