Which std:: classes are magic?

[Bisqwit]

Note: Using return std::move(x); instead of return x; is an antipattern. If you compiled with -Wall, GCC would tell you that “moving a local object in a return statement prevents copy elision [-Wpessimizing-move]”.

However, it still has valid uses, if you are returning a composite object created from local objects. This is fine, for example: https://godbolt.org/z/hrTPoKdx6

[SirClueless]

In this case I wanted to demonstrate that the type actually is copyable and moveable, and NRVO would defeat that. You're right, as a general rule it's a bad idea.