Not the GP, but for really large code bases, Go is missing a few features that I've noticed:
1) No immutable types. My work team is a huge user of immutable data stuctures in Java to make sure data passed around to other teams isn't changed. Go doesn't really have a good way to do this.
2) Refactoring can be really annoying (or at least really noisy) because of public/private being defined by capitalization of method/field names.
3) Error handling isn't great. I love Go's errors being just normal values, but the `error` interface is awkward when trying to figure out what kind of errors can be thrown without having in-depth knowledge of the kinds of errors that can be returned. We regularly need to make different decisions depending on the kind of error returned. Knowing which errors can be returned in Go is not defined by the method being called (only in comments).
> No immutable types (in Go)
The typical answer is opaque types with only readonly methods exported. Not elegant, but it’s there. I guess it’s arguably not a “good way” to do it.
This is not a dig at Go and this will be controversial but I so struggle to see what problem or area Go is solving outside of CSP. It's a nice language it just feels far too simple and I am really convinced of it as a systems language over Modern C++ and if you want that alternative then we have our rather oxidized friend that seems to more substantial. That's just my take.
I think you want sum types which admittedly Go doesn't have in a matchable way. However complex error recovery is an anti pattern for Go.