https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53637
--- Comment #5 from marc at kdab dot com --- You have a very narrow test of NRVO. You're using a completely transparent type, though I give you that defining the copy and move ctors in a separate TU does not change the outcome. At some point I'll check whether having them in a different dll/so/dylib will change something. And you consequently don't test X's which are not created at the top-level scope. These bug reports are about other cases. NRVO should kick in whenever it is statically known which object is returned. I will hand you a pull-request for some more soon, but in Qt, we have also returns of rvalues from some switch cases mixed with returns of case-local lvalues from others, which I didn't cover, yet. I only added slight variations of the existing tests. You seem to have an impressive array of compilers to run the test against, and I invite you to add more cases where lvalues are returned where NRVO could be used and update your interesting paper.
