[sledge] Improve frontend warnings
[sledge] Improve frontend warnings

Reviewed By: ngorogiannis

Differential Revision: D15403366

fbshipit-source-id: b4342a934

jvillard/infer,jvillard/infer,facebook/infer,jvillard/infer,jvillard/infer,facebook/infer,facebook/infer,jvillard/infer,facebook/infer,facebook/infer,jvillard/infer,facebook/infer,facebook/infer,jvillard/infer