Implementations may not deprecate a field that the interface hasn't deprecated

benjie · benjie · commit aade51b37c8a · 2023-11-09T11:58:47.000Z
diff --git a/spec/Section 3 -- Type System.md b/spec/Section 3 -- Type System.md
@@ -947,6 +947,8 @@ IsValidImplementation(type, implementedType):
        2. Let {implementedFieldType} be the return type of {implementedField}.
        3. {IsValidImplementationFieldType(fieldType, implementedFieldType)} must
           be {true}.
+    6. If the `@deprecated` directive is not applied to {implementedField}, then
+       the `@deprecated` directive must not be applied to {field}.
 
 IsValidImplementationFieldType(fieldType, implementedFieldType):
 
