[pcr910303]

While I don't think adding C++ interoperability is one of the'mashup of features', one example of a feature that adds complexity and conflicts is the function builders (result builders)[0].

It doesn't interact well with other language features (e.x. if let wasn't supported for a long time), it isn't really extensible (transforms are specified by the language), and yet it adds a bunch of complexity in both the language, implementation and reading code.

It seems clear, at least to me, that this is something that happens if you try to make a feature 'generic' without a lot of time and design consideration, due to Apple's internal politics on SwiftUI. I like SwiftUI, and some features that support it are great (like custom attributes), but I firmly think that they should have taked the time to produce a better design.

[0]: https://github.com/apple/swift-evolution/blob/main/proposals...