note a small diagnostic regression

the way these diagnostics were added seems to have been through score hacking
and I haven't been able to get the behavior back since introducing the
copyable type constraint for generics. I've logged restoring this as a TODO
to take care of sometime later when I have more time.

Author: kavon

test/Constraints/rdar68155466.swift

@@ -9,7 +9,8 @@ import Foundation
   }
 }
 
-struct Loop< // expected-note {{required by generic struct 'Loop' where 'ID' = '() -> Int'}}
+// FIXME: the diagnostic below ideally should have been emitted (rdar://106241733)
+struct Loop< // note {{required by generic struct 'Loop' where 'ID' = '() -> Int'}}
   Data : RandomAccessCollection,
   ID : Hashable,
   Content
@@ -25,4 +26,5 @@ func data() -> [A] {
 }
 
 _ = Loop(data(), id: \.uniqueID) { $0 } // expected-error {{key path cannot refer to instance method 'uniqueID()'}}
-// expected-error@-1 {{type '() -> Int' cannot conform to 'Hashable'}} expected-note@-1 {{only concrete types such as structs, enums and classes can conform to protocols}}
+// FIXME: the diagnostics below ideally should have been emitted (rdar://106241733)
+// error@-1 {{type '() -> Int' cannot conform to 'Hashable'}} note@-1 {{only concrete types such as structs, enums and classes can conform to protocols}}