Merge pull request #41786 from DougGregor/opened-archetypes-back-in-your-context

Stop mapping opened archetypes "out of context".

Author: DougGregor

lib/AST/ASTMangler.cpp

@@ -1323,10 +1323,16 @@ void ASTMangler::appendType(Type type, GenericSignature sig,
 
       // type ::= archetype
     case TypeKind::PrimaryArchetype:
-    case TypeKind::OpenedArchetype:
     case TypeKind::SequenceArchetype:
       llvm_unreachable("Cannot mangle free-standing archetypes");
 
+    case TypeKind::OpenedArchetype: {
+      // Opened archetypes have always been mangled via their interface type,
+      // although those manglings aren't used in any stable manner.
+      auto openedType = cast<OpenedArchetypeType>(tybase);
+      return appendType(openedType->getInterfaceType(), sig, forDecl);
+    }
+
     case TypeKind::OpaqueTypeArchetype: {
       auto opaqueType = cast<OpaqueTypeArchetypeType>(tybase);
       auto opaqueDecl = opaqueType->getDecl();

lib/AST/GenericEnvironment.cpp

@@ -242,7 +242,11 @@ Type MapTypeOutOfContext::operator()(SubstitutableType *type) const {
   auto archetype = cast<ArchetypeType>(type);
   if (isa<OpaqueTypeArchetypeType>(archetype->getRoot()))
     return Type();
-  
+
+  // Leave opened archetypes alone; they're handled contextually.
+  if (isa<OpenedArchetypeType>(archetype))
+    return Type(type);
+
   return archetype->getInterfaceType();
 }