Previously, the AbstractionPattern that was used for the value
"returned" (i.e. via a completion handler) from ObjC mostly (but not
quite always) was "type".
The generated completion handler correctly (because this is required in
order to call _resumeUnsafeContinuation) reabstracted the block (e.g.
from @convention(block) to @substituted <T> () -> @out T for <()>). The
callee of the ObjC function, however, loaded the function from the block
as if it were not reabstracted (e.g. () -> ()).
On most platforms, that happened to work. On arm64e, that difference in
types caused in a difference in pointer signing, resulting in a failure
at runtime.
rdar://85526879
rdar://85526916
Previously, the function emitCBridgedToNativeValue handled three
situations around optionals:
- Bridged?, Native?
- Bridged, Native?
- Bridged, Native
Here, handling for the fourth case
- Bridged?, Native
is added.
To enable this, the number of Optional wrappings that the bridged type
has that the native type does not is passed in to the function. Then,
in the portions of the function where actual transformations are done,
the values are unwrapped an appropriate number of times. Mostly that
means force unwrapping N times before doing the transformation. In the
case of types that conform to _ObjectiveCBridgeable, however, it means
force unwrapping the value N-1 times after doing the transformation
because _ObjectiveCBridgeable._unconditionallyBridgeFromObjectiveC
performs one layer of unwrapping itself.
rdar://81590807
