duplicates:

• SR-55 non-@objc protocol existentials do not conform to their own protocol type

relates to:

• SR-629 Protocol composition types should be covariant with composing protocols for protocol conformance
• SR-1581 Can not use protocol to fulfill associatedtype requirement where associatedType has protocol constraint

Issue Description:

protocol SettingsFile {}
protocol SpecificSettingsProvider {}     // NOTE: This doesn't inherit SettingsFile, on purpose. We use a composition instead.

protocol SettingsFileInfo {
    associatedtype FileType : SettingsFile
}

struct SpecificSettingsFileInfo : SettingsFileInfo {
    typealias FileType = protocol<SettingsFile, SpecificSettingsProvider>
}

Gives an error that SpecificSettingsFileInfo doesn't conform to SettingsFileInfo because FileType doesn't conform to SettingsFile.