~Copyable and functions

[taylorswift]

@Joe_Groff

There should be no reason to continue using __owned unless you're stuck with __owned affecting your symbol names in your ABI.

if i’m understanding correctly, does that mean the guidance here is no longer valid?

@jrose

The newly-accepted consume (your _move/take), and I think literally nothing else for a parameter. For a local you could assign nil over it, but parameters are alive for the entire function body in today's Swift, even __owned ones. Previously this lifetime was sometimes shortened; my understanding is that that doesn't happen anymore.

if so, i would consider that a massive improvement over what is specified in the ownership vision document. but it contradicts much of what we’ve been told about __owned so far.

tangentially, there is also an unattended compiler bug that causes very hard-to-debug ARC drift on 5.9 toolchains when using consuming.