That is, if you have this declaration:
struct Outer {
struct Inner {
// ...
}
}
and you're just printing 'Inner', print it like this:
struct Outer.Inner {
// ...
}
This comes up with the ClangImporter's import-as-member feature, and
is also about to affect how error code enums are imported as well.
This is currently only enabled in certain contexts: always when
printing interfaces, and for types (but not other members) when
printing declarations for Quick Help.
rdar://problem/28208090