Make conversions explicit (#46835)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/46835
We make explicit a couple of previously implicit down/narrowing conversions. This fixes a couple of compiler warnings.
Test Plan: Standard pre-commit test rig.
Reviewed By: ngimel
Differential Revision: D24481427
fbshipit-source-id: 8c9b0215a662ccdef8e2ba3df5f78ef110071f7b
