Tighten up error checking on manual_kernel_registration (#49341)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/49341
I noticed that #49097 was using manual_kernel_registration incorrectly,
so this diff tightens up the testing so that:
1. We don't generate useless wrapper functions when manual_kernel_registration
is on (it's not going to be registered, so it does nothing).
2. manual_kernel_registration shouldn't affect generation of functions in
Functions.h; if you need to stop bindings, use manual_cpp_binding
3. Structured and manual_kernel_registration are a hard error
4. We raise an error if you set dispatch and manual_kernel_registration at the
same time.
Signed-off-by: Edward Z. Yang <ezyang@fb.com>
Test Plan: Imported from OSS
Reviewed By: smessmer
Differential Revision: D25594003
Pulled By: ezyang
fbshipit-source-id: 655b10e9befdfd8bc95f1631b2f48f995a31a59a
