[Debug] Handle AnyObject.Protocol in stringForPrintObject(_:mangledTypeName:)

[kastiglione]

Update stringForPrintObject(_:mangledTypeName:) to support mangled type name for AnyObject ("yXlD"). Handle this by adding a second type is AnyObject.Protocol condition to the branch that bitcasts to AnyObject.

AnyObject is used by LLDB as a fallback when the dynamic type's mangled name contains a private class discriminator, which is not resolved by the Swift runtime.

Assisted-by: claude

[kastiglione]

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[augusto2112]

Do you know why _getTypeByMangledNameInContext cannot resolve AnyObject?

[mikeash]

The proper mangled name for AnyObject should be yXl (class-constrained existential with an empty protocol list). I'm not sure where s9AnyObjectaD comes from. We are able to look up yXl:

$ swift -e 'print(_typeByName("yXl")!)'
AnyObject

[kastiglione]

I'm not sure where s9AnyObjectaD comes from

It's a typealias declared by the stdlib (https://developer.apple.com/documentation/swift/anyobject). I've seen debug info reference both the alias (s9AnyObjectaD), and the builtin (yXlD).

I didn't go with the builtin because, although type lookup succeed, there were downstream failures that made me think I wasn't taking the right path. I'll debug further and find out where and why it fails after type lookup.

[kastiglione]

Thanks @mikeash, I've updated the code to support yXlD.

[kastiglione]

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[mikeash]

Capturing a bit of offline discussion: there's a difference between AnyObject.Type, which indicates a concrete type that conforms to AnyObject (i.e. any class type), and AnyObject.Protocol which indicates the AnyObject type itself. At least I think that's right....

[kastiglione]

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[kastiglione]

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