Check that move arguments are disjoint in the mir verifier

[bjorn3]

See https://rust-lang.zulipchat.com/#narrow/stream/136281-t-lang.2Fwg-unsafe-code-guidelines/topic/stack.20slot.20reuse.20Q/near/305409193 and #103362.

Basically the check would disallow foo(move _1, move _1) (where _1 is of any type) and foo(move *_1, move *_1) (where _1 is a box).

[RalfJung]

It should also reject foo(move _1, move *_1), probably.

[tmiasko]

One additional case that probably should be rejected: f(move _1, _1).

[scottmcm]

Is f(_1, move _1) allowed?

[bjorn3]

It could be, but it did be more consistent to disallow it and require an explicit copy rather than an implicit one.

[tmiasko]

There is an interesting report of a destination propagation introducing an overlap between moved argument and call destination in dead code #105344 (comment).

[bjorn3]

I think destination propagation should be fixed in that case.