I am with Raymond on this one.

If "protecting against wrong use" is the only reason to go down the slippery path of starting to rely on compiler optimizations for performance critical operations, the argument is not good enough.

If people do use macros in l-value mode, it's their problem when their code breaks, not ours. Please don't forget that we are operating under the consenting adults principle: we expect users of the CPython API to use it as documented and expect them to take care of the fallout, if things break when they don't.

We don't need to police developers into doing so.