Merge pull request #1049 from jskeet/any-format

Handle Any formatting for diagnostic purposes

csharp/src/AddressBook/Addressbook.cs

@@ -43,6 +43,9 @@ namespace Google.Protobuf.Examples.AddressBook {
 
   }
   #region Messages
+  /// <summary>
+  ///  [START messages]
+  /// </summary>
   [global::System.Diagnostics.DebuggerNonUserCodeAttribute()]
   public sealed partial class Person : pb::IMessage<Person> {
     private static readonly pb::MessageParser<Person> _parser = new pb::MessageParser<Person>(() => new Person());
@@ -143,7 +146,7 @@ namespace Google.Protobuf.Examples.AddressBook {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -302,7 +305,7 @@ namespace Google.Protobuf.Examples.AddressBook {
         }
 
         public override string ToString() {
-          return pb::JsonFormatter.Default.Format(this);
+          return pb::JsonFormatter.ToDiagnosticString(this);
         }
 
         public void WriteTo(pb::CodedOutputStream output) {
@@ -426,7 +429,7 @@ namespace Google.Protobuf.Examples.AddressBook {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {

csharp/src/Google.Protobuf.Conformance/Conformance.cs

@@ -284,7 +284,7 @@ namespace Conformance {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -532,7 +532,7 @@ namespace Conformance {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -1544,7 +1544,7 @@ namespace Conformance {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -2343,7 +2343,7 @@ namespace Conformance {
         }
 
         public override string ToString() {
-          return pb::JsonFormatter.Default.Format(this);
+          return pb::JsonFormatter.ToDiagnosticString(this);
         }
 
         public void WriteTo(pb::CodedOutputStream output) {
@@ -2471,7 +2471,7 @@ namespace Conformance {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {

csharp/src/Google.Protobuf.Test/TestProtos/MapUnittestProto3.cs

@@ -425,7 +425,7 @@ namespace Google.Protobuf.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -633,7 +633,7 @@ namespace Google.Protobuf.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -741,7 +741,7 @@ namespace Google.Protobuf.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -851,7 +851,7 @@ namespace Google.Protobuf.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -1121,7 +1121,7 @@ namespace Google.Protobuf.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -1318,7 +1318,7 @@ namespace Google.Protobuf.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -1427,7 +1427,7 @@ namespace Google.Protobuf.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {

csharp/src/Google.Protobuf.Test/TestProtos/UnittestImportProto3.cs

@@ -110,7 +110,7 @@ namespace Google.Protobuf.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {

csharp/src/Google.Protobuf.Test/TestProtos/UnittestImportPublicProto3.cs

@@ -96,7 +96,7 @@ namespace Google.Protobuf.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {

csharp/src/Google.Protobuf.Test/TestProtos/UnittestIssues.cs

@@ -126,7 +126,7 @@ namespace UnitTest.Issues.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -204,7 +204,7 @@ namespace UnitTest.Issues.TestProtos {
         }
 
         public override string ToString() {
-          return pb::JsonFormatter.Default.Format(this);
+          return pb::JsonFormatter.ToDiagnosticString(this);
         }
 
         public void WriteTo(pb::CodedOutputStream output) {
@@ -282,7 +282,7 @@ namespace UnitTest.Issues.TestProtos {
             }
 
             public override string ToString() {
-              return pb::JsonFormatter.Default.Format(this);
+              return pb::JsonFormatter.ToDiagnosticString(this);
             }
 
             public void WriteTo(pb::CodedOutputStream output) {
@@ -405,7 +405,7 @@ namespace UnitTest.Issues.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -511,7 +511,7 @@ namespace UnitTest.Issues.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -668,7 +668,7 @@ namespace UnitTest.Issues.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -831,7 +831,7 @@ namespace UnitTest.Issues.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -947,7 +947,7 @@ namespace UnitTest.Issues.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -1056,7 +1056,7 @@ namespace UnitTest.Issues.TestProtos {
         }
 
         public override string ToString() {
-          return pb::JsonFormatter.Default.Format(this);
+          return pb::JsonFormatter.ToDiagnosticString(this);
         }
 
         public void WriteTo(pb::CodedOutputStream output) {
@@ -1279,7 +1279,7 @@ namespace UnitTest.Issues.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {

csharp/src/Google.Protobuf.Test/TestProtos/UnittestProto3.cs

@@ -927,7 +927,7 @@ namespace Google.Protobuf.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -1600,7 +1600,7 @@ namespace Google.Protobuf.TestProtos {
         }
 
         public override string ToString() {
-          return pb::JsonFormatter.Default.Format(this);
+          return pb::JsonFormatter.ToDiagnosticString(this);
         }
 
         public void WriteTo(pb::CodedOutputStream output) {
@@ -1736,7 +1736,7 @@ namespace Google.Protobuf.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -1873,7 +1873,7 @@ namespace Google.Protobuf.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -1980,7 +1980,7 @@ namespace Google.Protobuf.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -2070,7 +2070,7 @@ namespace Google.Protobuf.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -2162,7 +2162,7 @@ namespace Google.Protobuf.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -2291,7 +2291,7 @@ namespace Google.Protobuf.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -2421,7 +2421,7 @@ namespace Google.Protobuf.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -2547,7 +2547,7 @@ namespace Google.Protobuf.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -2669,7 +2669,7 @@ namespace Google.Protobuf.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -2883,7 +2883,7 @@ namespace Google.Protobuf.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -3107,7 +3107,7 @@ namespace Google.Protobuf.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -3278,7 +3278,7 @@ namespace Google.Protobuf.TestProtos {
         }
 
         public override string ToString() {
-          return pb::JsonFormatter.Default.Format(this);
+          return pb::JsonFormatter.ToDiagnosticString(this);
         }
 
         public void WriteTo(pb::CodedOutputStream output) {
@@ -3400,7 +3400,7 @@ namespace Google.Protobuf.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -3506,7 +3506,7 @@ namespace Google.Protobuf.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -3608,7 +3608,7 @@ namespace Google.Protobuf.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -3704,7 +3704,7 @@ namespace Google.Protobuf.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -3807,7 +3807,7 @@ namespace Google.Protobuf.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -3913,7 +3913,7 @@ namespace Google.Protobuf.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -4016,7 +4016,7 @@ namespace Google.Protobuf.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -4119,7 +4119,7 @@ namespace Google.Protobuf.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -4222,7 +4222,7 @@ namespace Google.Protobuf.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -4325,7 +4325,7 @@ namespace Google.Protobuf.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -4486,7 +4486,7 @@ namespace Google.Protobuf.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -4780,7 +4780,7 @@ namespace Google.Protobuf.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -5140,7 +5140,7 @@ namespace Google.Protobuf.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -5414,7 +5414,7 @@ namespace Google.Protobuf.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -5554,7 +5554,7 @@ namespace Google.Protobuf.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -5647,7 +5647,7 @@ namespace Google.Protobuf.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -5723,7 +5723,7 @@ namespace Google.Protobuf.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -5799,7 +5799,7 @@ namespace Google.Protobuf.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -5875,7 +5875,7 @@ namespace Google.Protobuf.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -5951,7 +5951,7 @@ namespace Google.Protobuf.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -6027,7 +6027,7 @@ namespace Google.Protobuf.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {

csharp/src/Google.Protobuf.Test/TestProtos/UnittestWellKnownTypes.cs

@@ -466,7 +466,7 @@ namespace Google.Protobuf.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -1106,7 +1106,7 @@ namespace Google.Protobuf.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -1625,7 +1625,7 @@ namespace Google.Protobuf.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -2213,7 +2213,7 @@ namespace Google.Protobuf.TestProtos {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {

csharp/src/Google.Protobuf.Test/WellKnownTypes/AnyTest.cs

@@ -62,5 +62,28 @@ namespace Google.Protobuf.WellKnownTypes
             var unpacked = any.Unpack<TestAllTypes>();
             Assert.AreEqual(message, unpacked);
         }
+
+        [Test]
+        public void ToString_WithValues()
+        {
+            var message = SampleMessages.CreateFullTestAllTypes();
+            var any = Any.Pack(message);
+            var text = any.ToString();
+            Assert.That(text, Is.StringContaining("\"@value\": \"" + message.ToByteString().ToBase64() + "\""));
+        }
+
+        [Test]
+        public void ToString_Empty()
+        {
+            var any = new Any();
+            Assert.AreEqual("{ \"@type\": \"\", \"@value\": \"\" }", any.ToString());
+        }
+
+        [Test]
+        public void ToString_MessageContainingAny()
+        {
+            var message = new TestWellKnownTypes { AnyField = new Any() };
+            Assert.AreEqual("{ \"anyField\": { \"@type\": \"\", \"@value\": \"\" } }", message.ToString());
+        }
     }
 }

csharp/src/Google.Protobuf/JsonFormatter.cs

@@ -56,17 +56,19 @@ namespace Google.Protobuf
     public sealed class JsonFormatter
     {
         internal const string AnyTypeUrlField = "@type";
+        internal const string AnyDiagnosticValueField = "@value";
         internal const string AnyWellKnownTypeValueField = "value";
         private const string TypeUrlPrefix = "type.googleapis.com";
         private const string NameValueSeparator = ": ";
         private const string PropertySeparator = ", ";
 
-        private static JsonFormatter defaultInstance = new JsonFormatter(Settings.Default);
-
         /// <summary>
         /// Returns a formatter using the default settings.
         /// </summary>
-        public static JsonFormatter Default { get { return defaultInstance; } }
+        public static JsonFormatter Default { get; } = new JsonFormatter(Settings.Default);
+
+        // A JSON formatter which *only* exists 
+        private static readonly JsonFormatter diagnosticFormatter = new JsonFormatter(Settings.Default);
 
         /// <summary>
         /// The JSON representation of the first 160 characters of Unicode.
@@ -149,6 +151,29 @@ namespace Google.Protobuf
             return builder.ToString();
         }
 
+        /// <summary>
+        /// Converts a message to JSON for diagnostic purposes with no extra context.
+        /// </summary>
+        /// <remarks>
+        /// <para>
+        /// This differs from calling <see cref="Format(IMessage)"/> on the default JSON
+        /// formatter in its handling of <see cref="Any"/>. As no type registry is available
+        /// in <see cref="object.ToString"/> calls, the normal way of resolving the type of
+        /// an <c>Any</c> message cannot be applied. Instead, a JSON property named <c>@value</c>
+        /// is included with the base64 data from the <see cref="Any.Value"/> property of the message.
+        /// </para>
+        /// <para>The value returned by this method is only designed to be used for diagnostic
+        /// purposes. It may not be parsable by <see cref="JsonParser"/>, and may not be parsable
+        /// by other Protocol Buffer implementations.</para>
+        /// </remarks>
+        /// <param name="message">The message to format for diagnostic purposes.</param>
+        /// <returns>The diagnostic-only JSON representation of the message</returns>
+        public static string ToDiagnosticString(IMessage message)
+        {
+            Preconditions.CheckNotNull(message, nameof(message));
+            return diagnosticFormatter.Format(message);
+        }
+
         private void WriteMessage(StringBuilder builder, IMessage message)
         {
             if (message == null)
@@ -516,6 +541,12 @@ namespace Google.Protobuf
 
         private void WriteAny(StringBuilder builder, IMessage value)
         {
+            if (ReferenceEquals(this, diagnosticFormatter))
+            {
+                WriteDiagnosticOnlyAny(builder, value);
+                return;
+            }
+
             string typeUrl = (string) value.Descriptor.Fields[Any.TypeUrlFieldNumber].Accessor.GetValue(value);
             ByteString data = (ByteString) value.Descriptor.Fields[Any.ValueFieldNumber].Accessor.GetValue(value);
             string typeName = GetTypeName(typeUrl);
@@ -544,6 +575,23 @@ namespace Google.Protobuf
             builder.Append(" }");
         }
 
+        private void WriteDiagnosticOnlyAny(StringBuilder builder, IMessage value)
+        {
+            string typeUrl = (string) value.Descriptor.Fields[Any.TypeUrlFieldNumber].Accessor.GetValue(value);
+            ByteString data = (ByteString) value.Descriptor.Fields[Any.ValueFieldNumber].Accessor.GetValue(value);
+            builder.Append("{ ");
+            WriteString(builder, AnyTypeUrlField);
+            builder.Append(NameValueSeparator);
+            WriteString(builder, typeUrl);
+            builder.Append(PropertySeparator);
+            WriteString(builder, AnyDiagnosticValueField);
+            builder.Append(NameValueSeparator);
+            builder.Append('"');
+            builder.Append(data.ToBase64());
+            builder.Append('"');
+            builder.Append(" }");
+        }
+
         internal static string GetTypeName(String typeUrl)
         {
             string[] parts = typeUrl.Split('/');

csharp/src/Google.Protobuf/Reflection/Descriptor.cs

@@ -225,7 +225,7 @@ namespace Google.Protobuf.Reflection {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -489,7 +489,7 @@ namespace Google.Protobuf.Reflection {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -827,7 +827,7 @@ namespace Google.Protobuf.Reflection {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -1021,7 +1021,7 @@ namespace Google.Protobuf.Reflection {
         }
 
         public override string ToString() {
-          return pb::JsonFormatter.Default.Format(this);
+          return pb::JsonFormatter.ToDiagnosticString(this);
         }
 
         public void WriteTo(pb::CodedOutputStream output) {
@@ -1162,7 +1162,7 @@ namespace Google.Protobuf.Reflection {
         }
 
         public override string ToString() {
-          return pb::JsonFormatter.Default.Format(this);
+          return pb::JsonFormatter.ToDiagnosticString(this);
         }
 
         public void WriteTo(pb::CodedOutputStream output) {
@@ -1436,7 +1436,7 @@ namespace Google.Protobuf.Reflection {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -1741,7 +1741,7 @@ namespace Google.Protobuf.Reflection {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -1872,7 +1872,7 @@ namespace Google.Protobuf.Reflection {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -2031,7 +2031,7 @@ namespace Google.Protobuf.Reflection {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -2196,7 +2196,7 @@ namespace Google.Protobuf.Reflection {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -2404,7 +2404,7 @@ namespace Google.Protobuf.Reflection {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -2863,7 +2863,7 @@ namespace Google.Protobuf.Reflection {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -3302,7 +3302,7 @@ namespace Google.Protobuf.Reflection {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -3596,7 +3596,7 @@ namespace Google.Protobuf.Reflection {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -3845,7 +3845,7 @@ namespace Google.Protobuf.Reflection {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -3990,7 +3990,7 @@ namespace Google.Protobuf.Reflection {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -4121,7 +4121,7 @@ namespace Google.Protobuf.Reflection {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -4252,7 +4252,7 @@ namespace Google.Protobuf.Reflection {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -4451,7 +4451,7 @@ namespace Google.Protobuf.Reflection {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -4653,7 +4653,7 @@ namespace Google.Protobuf.Reflection {
         }
 
         public override string ToString() {
-          return pb::JsonFormatter.Default.Format(this);
+          return pb::JsonFormatter.ToDiagnosticString(this);
         }
 
         public void WriteTo(pb::CodedOutputStream output) {
@@ -4823,7 +4823,7 @@ namespace Google.Protobuf.Reflection {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -5051,7 +5051,7 @@ namespace Google.Protobuf.Reflection {
         }
 
         public override string ToString() {
-          return pb::JsonFormatter.Default.Format(this);
+          return pb::JsonFormatter.ToDiagnosticString(this);
         }
 
         public void WriteTo(pb::CodedOutputStream output) {

csharp/src/Google.Protobuf/WellKnownTypes/Any.cs

@@ -165,7 +165,7 @@ namespace Google.Protobuf.WellKnownTypes {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {

csharp/src/Google.Protobuf/WellKnownTypes/Api.cs

@@ -230,7 +230,7 @@ namespace Google.Protobuf.WellKnownTypes {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -503,7 +503,7 @@ namespace Google.Protobuf.WellKnownTypes {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -783,7 +783,7 @@ namespace Google.Protobuf.WellKnownTypes {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {

csharp/src/Google.Protobuf/WellKnownTypes/Duration.cs

@@ -164,7 +164,7 @@ namespace Google.Protobuf.WellKnownTypes {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {

csharp/src/Google.Protobuf/WellKnownTypes/Empty.cs

@@ -94,7 +94,7 @@ namespace Google.Protobuf.WellKnownTypes {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {

csharp/src/Google.Protobuf/WellKnownTypes/FieldMask.cs

@@ -221,7 +221,7 @@ namespace Google.Protobuf.WellKnownTypes {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {

csharp/src/Google.Protobuf/WellKnownTypes/SourceContext.cs

@@ -105,7 +105,7 @@ namespace Google.Protobuf.WellKnownTypes {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {

csharp/src/Google.Protobuf/WellKnownTypes/Struct.cs

@@ -136,7 +136,7 @@ namespace Google.Protobuf.WellKnownTypes {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -361,7 +361,7 @@ namespace Google.Protobuf.WellKnownTypes {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -555,7 +555,7 @@ namespace Google.Protobuf.WellKnownTypes {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {

csharp/src/Google.Protobuf/WellKnownTypes/Timestamp.cs

@@ -175,7 +175,7 @@ namespace Google.Protobuf.WellKnownTypes {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {

csharp/src/Google.Protobuf/WellKnownTypes/Type.cs

@@ -230,7 +230,7 @@ namespace Google.Protobuf.WellKnownTypes {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -522,7 +522,7 @@ namespace Google.Protobuf.WellKnownTypes {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -910,7 +910,7 @@ namespace Google.Protobuf.WellKnownTypes {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -1098,7 +1098,7 @@ namespace Google.Protobuf.WellKnownTypes {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -1244,7 +1244,7 @@ namespace Google.Protobuf.WellKnownTypes {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {

csharp/src/Google.Protobuf/WellKnownTypes/Wrappers.cs

@@ -117,7 +117,7 @@ namespace Google.Protobuf.WellKnownTypes {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -228,7 +228,7 @@ namespace Google.Protobuf.WellKnownTypes {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -339,7 +339,7 @@ namespace Google.Protobuf.WellKnownTypes {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -450,7 +450,7 @@ namespace Google.Protobuf.WellKnownTypes {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -561,7 +561,7 @@ namespace Google.Protobuf.WellKnownTypes {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -672,7 +672,7 @@ namespace Google.Protobuf.WellKnownTypes {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -783,7 +783,7 @@ namespace Google.Protobuf.WellKnownTypes {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -894,7 +894,7 @@ namespace Google.Protobuf.WellKnownTypes {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {
@@ -1005,7 +1005,7 @@ namespace Google.Protobuf.WellKnownTypes {
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {

src/google/protobuf/compiler/csharp/csharp_message.cc

@@ -353,7 +353,7 @@ void MessageGenerator::GenerateFrameworkMethods(io::Printer* printer) {
 
     printer->Print(
         "public override string ToString() {\n"
-        "  return pb::JsonFormatter.Default.Format(this);\n"
+        "  return pb::JsonFormatter.ToDiagnosticString(this);\n"
         "}\n\n");
 }