I'm sure user-defined structs can benefit from combining information from multiple functions, but saying that what you get today is “basically none” is a bit of

I'm sure user-defined structs can benefit from combining information from multiple functions, but saying that what you get today is “basically none” is a bit of an overstatement. Also, the special (and important!) case of operating system ABI structs is great, and that information propagates throughout function calls.