There might be duplicated enum values when allow_alias is true. Add PreferredAlias into OriginalNameAttribute to remove the duplication (#2727)

2 files changed, 13 insertions, 1 deletions

diff --git a/csharp/src/Google.Protobuf/JsonFormatter.cs b/csharp/src/Google.Protobuf/JsonFormatter.cs
index 05282775..90c2e937 100755
--- a/csharp/src/Google.Protobuf/JsonFormatter.cs
+++ b/csharp/src/Google.Protobuf/JsonFormatter.cs
@@ -835,6 +835,9 @@ namespace Google.Protobuf
             // TODO: Consider adding functionality to TypeExtensions to avoid this difference.
             private static Dictionary<object, string> GetNameMapping(System.Type enumType) =>
                 enumType.GetFields(BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Static)
+                    .Where(f => (f.GetCustomAttributes(typeof(OriginalNameAttribute), false)
+                                 .FirstOrDefault() as OriginalNameAttribute)
+                                 ?.PreferredAlias ?? true)
                     .ToDictionary(f => f.GetValue(null),
                                   f => (f.GetCustomAttributes(typeof(OriginalNameAttribute), false)
                                         .FirstOrDefault() as OriginalNameAttribute)
@@ -844,6 +847,8 @@ namespace Google.Protobuf
             private static Dictionary<object, string> GetNameMapping(System.Type enumType) =>
                 enumType.GetTypeInfo().DeclaredFields
                     .Where(f => f.IsStatic)
+                    .Where(f => f.GetCustomAttributes<OriginalNameAttribute>()
+                                 .FirstOrDefault()?.PreferredAlias ?? true)
                     .ToDictionary(f => f.GetValue(null),
                                   f => f.GetCustomAttributes<OriginalNameAttribute>()
                                         .FirstOrDefault()
diff --git a/csharp/src/Google.Protobuf/Reflection/OriginalNameAttribute.cs b/csharp/src/Google.Protobuf/Reflection/OriginalNameAttribute.cs
index 27f9ab98..07d0fd99 100644
--- a/csharp/src/Google.Protobuf/Reflection/OriginalNameAttribute.cs
+++ b/csharp/src/Google.Protobuf/Reflection/OriginalNameAttribute.cs
@@ -47,12 +47,19 @@ namespace Google.Protobuf.Reflection
         public string Name { get; set; }
 
         /// <summary>
+        /// If the name is preferred in the .proto file.
+        /// </summary>
+        public bool PreferredAlias { get; set; }
+
+        /// <summary>
         /// Constructs a new attribute instance for the given name.
         /// </summary>
         /// <param name="name">The name of the element in the .proto file.</param>
         public OriginalNameAttribute(string name)
         {
             Name = ProtoPreconditions.CheckNotNull(name, nameof(name));
+            PreferredAlias = true;
         }
+	
     }
-}
\ No newline at end of file
+}