[prespecialized metadata] Note classes are complete.

include/swift/ABI/Metadata.h

@@ -1295,6 +1295,14 @@ struct TargetClassMetadata : public TargetAnyClassMetadata<Runtime> {
     assert(isTypeMetadata());
   }
 
+  bool isCanonicalStaticallySpecializedGenericMetadata() const {
+    auto *description = getDescription();
+    if (!description->isGeneric())
+      return false;
+
+    return this->Flags & ClassFlags::IsCanonicalStaticSpecialization;
+  }
+
   static bool classof(const TargetMetadata<Runtime> *metadata) {
     return metadata->getKind() == MetadataKind::Class;
   }

include/swift/ABI/MetadataValues.h

@@ -265,7 +265,16 @@ enum class ClassFlags : uint32_t {
   UsesSwiftRefcounting = 0x2,
 
   /// Has this class a custom name, specified with the @objc attribute?
-  HasCustomObjCName = 0x4
+  HasCustomObjCName = 0x4,
+
+  /// Whether this metadata is a specialization of a generic metadata pattern
+  /// which was created during compilation.
+  IsStaticSpecialization = 0x8,
+
+  /// Whether this metadata is a specialization of a generic metadata pattern
+  /// which was created during compilation and made to be canonical by
+  /// modifying the metadata accessor.
+  IsCanonicalStaticSpecialization = 0x10,
 };
 inline bool operator&(ClassFlags a, ClassFlags b) {
   return (uint32_t(a) & uint32_t(b)) != 0;

stdlib/public/runtime/Metadata.cpp

@@ -5512,6 +5512,8 @@ bool Metadata::isCanonicalStaticallySpecializedGenericMetadata() const {
     return metadata->isCanonicalStaticallySpecializedGenericMetadata();
   if (auto *metadata = dyn_cast<EnumMetadata>(this))
     return metadata->isCanonicalStaticallySpecializedGenericMetadata();
+  if (auto *metadata = dyn_cast<ClassMetadata>(this))
+    return metadata->isCanonicalStaticallySpecializedGenericMetadata();
 
   return false;
 }