How to warn about std::move resulting in a copy

Clang Frontend
#1

I was listening to Scott Meyers’s talk at Going Native 2013 and it was mentioned that a warning about a call to std::move resulting in a copy instead of a move would cause so many false positives that it would be useless.

Obviously it wouldn’t be useful to warn every time a return from std::move is copied, but maybe there is a subset that would be useful. My thoughts on what set of circumstances might lead to a useful warning.

  1. Value returned from std::move is copied

  2. Value returned from std::move is movable

  3. Value returned from std::move is const qualified

Is there other set of restrictions that might be needed to make this useful?