r328404 has been committed to support references and pointers.

Looks good. Ready to commit.

Two more changes, then everything is good to commit.

Everything looks good and ready for commit.

I believe you were around this code last, so can you remember why it was there?

Yes, that's an early exit to speed up the check. You can remove that check and add a test case for it.

Can you explain the new algorithm for checking recursive calls?

I have one very minor nit that I don't know how to fix:

warn-return-std-move.cpp:220:12: warning: local variable 'd' will be copied
      despite being returned by name [-Wreturn-std-move]
    return (d);  // e17
           ^
warn-return-std-move.cpp:220:12: note: call 'std::move' explicitly to avoid copying
    return (d);  // e17
           ^~~
           std::move(d)

The warning places a caret directly under the (, when I wish it would place ^~~ under the entire expression, the way the fixit does.

You can add extra tildes to any diagnostic by passing a SourceRange to Diag() calls the same way you pass FixitHints.

Reid is correct, the whitelisted expressions was greatly reduced during code review so only casts to void would disable the warning. While the last review did not have the description updated to reflect this, the committed code does have an accurate description. What is the reason to exclude void expressions now? For the function case, it is more consistent to warn on all function calls since we can't determine if a function returns void just by looking at the call site.