Don't build opaque archetypes referencing the outer environment.

When there are same-type constraints involving opaque archetype
parameters and generic parameters of the enclosing environment, a
nested type of an opaque type archetype might in fact refer to
something in the outer environment of the opaque type. Recognize this
case and perform substitutions on such types using the opaque type's
substitutions.

Author: DougGregor

lib/AST/GenericEnvironment.cpp

@@ -362,12 +362,24 @@ GenericEnvironment::getOrCreateArchetypeFromInterfaceType(Type depType) {
       break;
     }
 
-    case Kind::Opaque:
+    case Kind::Opaque: {
+      // If the anchor type isn't rooted in a generic parameter that
+      // represents an opaque declaration, then apply the outer substitutions.
+      // It would be incorrect to build an opaque type archetype here.
+      auto rootGP = requirements.anchor->getRootGenericParam();
+      unsigned opaqueDepth =
+          getOpaqueTypeDecl()->getOpaqueGenericParams().front()->getDepth();
+      if (rootGP->getDepth() < opaqueDepth) {
+        result = maybeApplyOpaqueTypeSubstitutions(requirements.anchor);
+        break;
+      }
+
       result = OpaqueTypeArchetypeType::getNew(this, requirements.anchor,
                                                requirements.protos, superclass,
                                                requirements.layout);
       break;
     }
+    }
   }
 
   if (genericParam)

test/Interpreter/named_opaque_result_types.swift

@@ -34,8 +34,7 @@ struct X<T, U: Hashable>: P {
   func f() -> <
       R1: Collection, R2: Collection where R1.Element == T, R2.Element == U
   > (R1, R2) {
-    // FIXME: Use unzipCollection here
-    return (Array(data.map { $0.0 }), Set(data.map { $0.1 }))
+    return unzipCollection(data)
   }
 }
 
@@ -71,6 +70,7 @@ if #available(iOS 13, macOS 10.15, tvOS 13, watchOS 6, *) {
   print("too old")
   print("too old")
   print("too old")
+
   print("too old")
   print("too old")
 }