tbkka b8c090d9c6 [SR-3871] Unwrap multiple layers of Any/AnyObject when casting to protocol type (#28835) ...

SR-3871: Dynamic casting of existentials stored in Obj-C references

Arbitrary Swift objects get packaged into __SwiftValue containers so
that pointers to them can be passed into Obj-C.  (Obviously, Obj-C
code can't do anything particularly useful with such pointers other
than refcount them and give them back to Swift code.)  Those values come
back into Swift as either `Any` (existential box) or `AnyObject`
(anonymous object pointer) values.  Dynamically casting those requires
first inspecting the outer value to get access to the actual type and
value in the __SwiftValue container.

The tryDynamicCastBoxedSwiftValue() function that handles this
was missing a check for the `Any` case, which is why directly
casting from `Any` would routinely fail.

Resolves SR-3871

2020-01-17 12:41:44 -08:00

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