Is there a way to check if RVO was applied?

I had this whole story about my frustrating journey to finding out that an unordered map I was returning from a function was not in fact RVO'd even though I was certain it was at an earlier time that it was but irrelevant.

Is there a way to check if RVO is happening in any given function? Or like a list of do's and dont's to follow to get the outcome I desire?