Swift Macro inheritance with nested class

[vanvoorden (Rick van Voorden)]

ExtensionMacro on a nested type does not generate extension at top level?

Hi! I'm seeing some unexpected behavior with using ExtensionMacro. According to SE-0402[1] we can expect that an ExtensionMacro applied to a nested type will generate an extension at top-level. I am testing with an ExtensionMacro example from the swift-syntax repo and I am seeing the extension generated at local scope: struct Outer { @Observable struct Inner {} } Expands to: struct Outer { struct Inner { let _registrar = ObservationRegistrar<Inner >() public nonisol…

I saw something similar… it might be the same problem in the task that was filed.

Does your code compile correctly when the macro is expanding through the compiler? Is the bug happening just when expanding or inlining the macro through Xcode before compiling?

@Tof

I just want to change the inheritance of the class on which the macro applies, not to create an extension.

For the most part macros are designed to be strictly additive… you can add new code… but not edit or remove code. There are a few exceptions to this rule… but for your specific use-case it sounds like you should declare an extension on SubClass with the protocols you want to adopt.