decoration of `id` - Githubissues

microsoft / WinObjC

Objective-C for Windows

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decoration of `id` #2789

Closed compnerd closed 7 years ago

compnerd commented 7 years ago

Currently id is decorated as PAAUobjc_object@@ which undname is unable to symbolicate. However, It is unclear whether this is accidental and the decorated name should be PAUobjc_object@@. This properly is undecorated by undname as struct objc_object *.

compnerd commented 7 years ago

CC: @DHowett-MSFT @DHowett

DHowett-MSFT commented 7 years ago

@compnerd Thanks for reporting this. It looks like it should be PAUobjc_object@@.

What issue are you seeing because of this? I think PAAUobjc_object@@ should still unmangle as Uobjc_object* (losing the struct typekind.)

DHowett-MSFT commented 7 years ago

(source: MicrosoftMangle in llvm-mirror here primes the mangled name with PA, then calls mangleArtificalTagType, which should emit U then the name. The code here looks right.)

compnerd commented 7 years ago

Yeah, it does result in Uobjc_object *. I shall fix clang (upstream) to generate this name properly. However, doing so means that

previously compiled objects will need to be rebuilt
the exception handling needs to be adjusted for the correct mangling of id for the root type CatchableType entry

Incorrectly decorating this means that compatibility across C++/ObjC++ is lost, so it is something which would be beneficial to address.

compnerd commented 7 years ago

SVN r3117617 will now mangle id, Class, and @interface appropriately in the C++ context. I have more questions about the decorations, is this the best channel for them?

compnerd commented 7 years ago

clang now generates the right thing.