Add ReferenceHandler to JsonSourceGenerationOptions

src/libraries/System.Text.Json/Common/JsonKnownReferenceHandler.cs

@@ -0,0 +1,26 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+namespace System.Text.Json.Serialization
+{
+    /// <summary>
+    /// The <see cref="ReferenceHandler"/> to be used at run time.
+    /// </summary>
+    public enum JsonKnownReferenceHandler
+    {
+        /// <summary>
+        /// Specifies that circular references should throw exceptions.
+        /// </summary>
+        Unspecified = 0,
+
+        /// <summary>
+        /// Specifies that the built-in <see cref="ReferenceHandler.Preserve"/> be used to handle references.
+        /// </summary>
+        Preserve = 1,
+
+        /// <summary>
+        /// Specifies that the built-in <see cref="ReferenceHandler.IgnoreCycles"/> be used to ignore cyclic references.
+        /// </summary>
+        IgnoreCycles = 2,
+    }
+}

src/libraries/System.Text.Json/Common/JsonSourceGenerationOptionsAttribute.cs

@@ -115,6 +115,11 @@ public JsonSourceGenerationOptionsAttribute(JsonSerializerDefaults defaults)
         /// </summary>
         public JsonCommentHandling ReadCommentHandling { get; set; }
 
+        /// <summary>
+        /// Specifies the default value of <see cref="JsonSerializerOptions.ReferenceHandler"/> when set.
+        /// </summary>
+        public JsonKnownReferenceHandler ReferenceHandler { get; set; }
+
         /// <summary>
         /// Specifies the default value of <see cref="JsonSerializerOptions.RespectNullableAnnotations"/> when set.
         /// </summary>

src/libraries/System.Text.Json/gen/JsonSourceGenerator.Emitter.cs

@@ -70,6 +70,7 @@ private sealed partial class Emitter
             private const string JsonPropertyInfoValuesTypeRef = "global::System.Text.Json.Serialization.Metadata.JsonPropertyInfoValues";
             private const string JsonTypeInfoTypeRef = "global::System.Text.Json.Serialization.Metadata.JsonTypeInfo";
             private const string JsonTypeInfoResolverTypeRef = "global::System.Text.Json.Serialization.Metadata.IJsonTypeInfoResolver";
+            private const string ReferenceHandlerTypeRef = "global::System.Text.Json.Serialization.ReferenceHandler";
             private const string EmptyTypeArray = "global::System.Array.Empty<global::System.Type>()";
 
             /// <summary>
@@ -1246,6 +1247,9 @@ private static void GetLogicForDefaultSerializerOptionsInit(SourceGenerationOpti
                 if (optionsSpec.ReadCommentHandling is JsonCommentHandling readCommentHandling)
                     writer.WriteLine($"ReadCommentHandling = {FormatCommentHandling(readCommentHandling)},");
 
+                if (optionsSpec.ReferenceHandler is JsonKnownReferenceHandler referenceHandler)
+                    writer.WriteLine($"ReferenceHandler = {FormatReferenceHandler(referenceHandler)},");
+
                 if (optionsSpec.UnknownTypeHandling is JsonUnknownTypeHandling unknownTypeHandling)
                     writer.WriteLine($"UnknownTypeHandling = {FormatUnknownTypeHandling(unknownTypeHandling)},");
 
@@ -1433,6 +1437,9 @@ private static string FormatIgnoreCondition(JsonIgnoreCondition ignoreCondition)
             private static string FormatJsonSerializerDefaults(JsonSerializerDefaults defaults)
                 => SourceGeneratorHelpers.FormatEnumLiteral(JsonSerializerDefaultsTypeRef, defaults);
 
+            private static string FormatReferenceHandler(JsonKnownReferenceHandler referenceHandler)
+                => SourceGeneratorHelpers.FormatEnumLiteral(ReferenceHandlerTypeRef, referenceHandler);
+
             private static string GetCreateValueInfoMethodRef(string typeCompilableName) => $"{CreateValueInfoMethodName}<{typeCompilableName}>";
 
             private static string FormatBoolLiteral(bool value) => value ? "true" : "false";

src/libraries/System.Text.Json/gen/JsonSourceGenerator.Parser.cs

@@ -280,6 +280,7 @@ private SourceGenerationOptionsSpec ParseJsonSourceGenerationOptionsAttribute(IN
                 bool? propertyNameCaseInsensitive = null;
                 JsonKnownNamingPolicy? propertyNamingPolicy = null;
                 JsonCommentHandling? readCommentHandling = null;
+                JsonKnownReferenceHandler? referenceHandler = null;
                 JsonUnknownTypeHandling? unknownTypeHandling = null;
                 JsonUnmappedMemberHandling? unmappedMemberHandling = null;
                 bool? useStringEnumConverter = null;
@@ -379,6 +380,10 @@ private SourceGenerationOptionsSpec ParseJsonSourceGenerationOptionsAttribute(IN
                             readCommentHandling = (JsonCommentHandling)namedArg.Value.Value!;
                             break;
 
+                        case nameof(JsonSourceGenerationOptionsAttribute.ReferenceHandler):
+                            referenceHandler = (JsonKnownReferenceHandler)namedArg.Value.Value!;
+                            break;
+
                         case nameof(JsonSourceGenerationOptionsAttribute.UnknownTypeHandling):
                             unknownTypeHandling = (JsonUnknownTypeHandling)namedArg.Value.Value!;
                             break;
@@ -434,6 +439,7 @@ private SourceGenerationOptionsSpec ParseJsonSourceGenerationOptionsAttribute(IN
                     PropertyNameCaseInsensitive = propertyNameCaseInsensitive,
                     PropertyNamingPolicy = propertyNamingPolicy,
                     ReadCommentHandling = readCommentHandling,
+                    ReferenceHandler = referenceHandler,
                     UnknownTypeHandling = unknownTypeHandling,
                     UnmappedMemberHandling = unmappedMemberHandling,
                     UseStringEnumConverter = useStringEnumConverter,

src/libraries/System.Text.Json/gen/Model/SourceGenerationOptionsSpec.cs

@@ -52,6 +52,8 @@ public sealed record SourceGenerationOptionsSpec
 
         public required JsonCommentHandling? ReadCommentHandling { get; init; }
 
+        public required JsonKnownReferenceHandler? ReferenceHandler { get; init; }
+
         public required JsonUnknownTypeHandling? UnknownTypeHandling { get; init; }
 
         public required JsonUnmappedMemberHandling? UnmappedMemberHandling { get; init; }

src/libraries/System.Text.Json/gen/System.Text.Json.SourceGeneration.targets

@@ -46,6 +46,7 @@
     <Compile Include="..\Common\JsonKebabCaseLowerNamingPolicy.cs" Link="Common\System\Text\Json\Serialization\JsonKebabCaseLowerNamingPolicy.cs" />
     <Compile Include="..\Common\JsonKebabCaseUpperNamingPolicy.cs" Link="Common\System\Text\Json\Serialization\JsonKebabCaseUpperNamingPolicy.cs" />
     <Compile Include="..\Common\JsonKnownNamingPolicy.cs" Link="Common\System\Text\Json\Serialization\JsonKnownNamingPolicy.cs" />
+    <Compile Include="..\Common\JsonKnownReferenceHandler.cs" Link="Common\System\Text\Json\Serialization\JsonKnownReferenceHandler.cs" />
     <Compile Include="..\Common\JsonNumberHandling.cs" Link="Common\System\Text\Json\Serialization\JsonNumberHandling.cs" />
     <Compile Include="..\Common\JsonObjectCreationHandling.cs" Link="Common\System\Text\Json\Serialization\JsonObjectCreationHandling.cs" />
     <Compile Include="..\Common\JsonSeparatorNamingPolicy.cs" Link="Common\System\Text\Json\Serialization\JsonSeparatorNamingPolicy.cs" />

src/libraries/System.Text.Json/ref/System.Text.Json.cs

@@ -1043,6 +1043,12 @@ public enum JsonKnownNamingPolicy
         KebabCaseLower = 4,
         KebabCaseUpper = 5,
     }
+    public enum JsonKnownReferenceHandler
+    {
+        Unspecified = 0,
+        Preserve = 1,
+        IgnoreCycles = 2,
+    }
     public sealed partial class JsonNumberEnumConverter<TEnum> : System.Text.Json.Serialization.JsonConverterFactory where TEnum : struct, System.Enum
     {
         public JsonNumberEnumConverter() { }
@@ -1143,6 +1149,7 @@ public JsonSourceGenerationOptionsAttribute(System.Text.Json.JsonSerializerDefau
         public bool PropertyNameCaseInsensitive { get { throw null; } set { } }
         public System.Text.Json.Serialization.JsonKnownNamingPolicy PropertyNamingPolicy { get { throw null; } set { } }
         public System.Text.Json.JsonCommentHandling ReadCommentHandling { get { throw null; } set { } }
+        public System.Text.Json.Serialization.JsonKnownReferenceHandler ReferenceHandler { get { throw null; } set { } }
         public bool RespectNullableAnnotations { get { throw null; } set { } }
         public bool RespectRequiredConstructorParameters { get { throw null; } set { } }
         public System.Text.Json.Serialization.JsonUnknownTypeHandling UnknownTypeHandling { get { throw null; } set { } }

src/libraries/System.Text.Json/src/System.Text.Json.csproj

@@ -33,9 +33,9 @@ The System.Text.Json library is built-in as part of the shared framework in .NET
     <Compile Include="..\Common\JsonKebabCaseLowerNamingPolicy.cs" Link="Common\System\Text\Json\Serialization\JsonKebabCaseLowerNamingPolicy.cs" />
     <Compile Include="..\Common\JsonKebabCaseUpperNamingPolicy.cs" Link="Common\System\Text\Json\Serialization\JsonKebabCaseUpperNamingPolicy.cs" />
     <Compile Include="..\Common\JsonKnownNamingPolicy.cs" Link="Common\System\Text\Json\Serialization\JsonKnownNamingPolicy.cs" />
+    <Compile Include="..\Common\JsonKnownReferenceHandler.cs" Link="Common\System\Text\Json\Serialization\JsonKnownReferenceHandler.cs" />
     <Compile Include="..\Common\JsonNumberHandling.cs" Link="Common\System\Text\Json\Serialization\JsonNumberHandling.cs" />
     <Compile Include="..\Common\JsonObjectCreationHandling.cs" Link="Common\System\Text\Json\Serialization\JsonObjectCreationHandling.cs" />
-    <Compile Include="..\Common\JsonUnmappedMemberHandling.cs" Link="Common\System\Text\Json\Serialization\JsonUnmappedMemberHandling.cs" />
     <Compile Include="..\Common\JsonSeparatorNamingPolicy.cs" Link="Common\System\Text\Json\Serialization\JsonSeparatorNamingPolicy.cs" />
     <Compile Include="..\Common\JsonSerializableAttribute.cs" Link="Common\System\Text\Json\Serialization\JsonSerializableAttribute.cs" />
     <Compile Include="..\Common\JsonSerializerDefaults.cs" Link="Common\System\Text\Json\Serialization\JsonSerializerDefaults.cs" />
@@ -44,6 +44,7 @@ The System.Text.Json library is built-in as part of the shared framework in .NET
     <Compile Include="..\Common\JsonSourceGenerationMode.cs" Link="Common\System\Text\Json\Serialization\JsonSourceGenerationMode.cs" />
     <Compile Include="..\Common\JsonSourceGenerationOptionsAttribute.cs" Link="Common\System\Text\Json\Serialization\JsonSourceGenerationOptionsAttribute.cs" />
     <Compile Include="..\Common\JsonUnknownTypeHandling.cs" Link="Common\System\Text\Json\Serialization\JsonUnknownTypeHandling.cs" />
+    <Compile Include="..\Common\JsonUnmappedMemberHandling.cs" Link="Common\System\Text\Json\Serialization\JsonUnmappedMemberHandling.cs" />
     <Compile Include="..\Common\ReflectionExtensions.cs" Link="Common\System\Text\Json\Serialization\ReflectionExtensions.cs" />
     <Compile Include="..\Common\ThrowHelper.cs" Link="Common\System\Text\Json\ThrowHelper.cs" />
     <Compile Include="System\Runtime\InteropServices\JsonMarshal.cs" />

src/libraries/System.Text.Json/src/System/Text/Json/Serialization/ReferenceHandlingStrategy.cs

@@ -5,8 +5,8 @@ namespace System.Text.Json.Serialization
 {
     internal enum ReferenceHandlingStrategy
     {
-        None,
-        Preserve,
-        IgnoreCycles
+        None = 0,
+        Preserve = 1,
+        IgnoreCycles = 2,
     }
 }

src/libraries/System.Text.Json/tests/System.Text.Json.SourceGeneration.Tests/JsonSerializerContextTests.cs

@@ -846,5 +846,37 @@ public static void ContextWithInterpolatedAnnotations_WorksAsExpected()
         internal partial class ContextWithInterpolatedAnnotations : JsonSerializerContext
         {
         }
+
+        [Fact]
+        public static async Task SupportsReferences()
+        {
+            ContextWithPreserveReference context = ContextWithPreserveReference.Default;
+            var selfRef = new SelfReference();
+            selfRef.Me = selfRef;
+
+            string expectedJson = """{"$id":"1","Me":{"$ref":"1"}}""";
+
+            string json = JsonSerializer.Serialize(selfRef, context.SelfReference);
+            Assert.Equal(expectedJson, json);
+
+            var stream = new Utf8MemoryStream();
+            await JsonSerializer.SerializeAsync(stream, selfRef, typeof(SelfReference), context);
+            Assert.Equal(expectedJson, stream.AsString());
+
+            SelfReference deserialized = JsonSerializer.Deserialize(expectedJson, context.SelfReference);
+            Assert.Same(deserialized, deserialized.Me);
+        }
+
+        [JsonSourceGenerationOptions(
+            ReferenceHandler = JsonKnownReferenceHandler.Preserve)]
+        [JsonSerializable(typeof(SelfReference))]
+        internal partial class ContextWithPreserveReference : JsonSerializerContext
+        {
+        }
+
+        internal class SelfReference
+        {
+            public SelfReference Me { get; set; }
+        }
     }
 }

src/libraries/System.Text.Json/tests/System.Text.Json.SourceGeneration.Tests/JsonSourceGenerationOptionsTests.cs

@@ -77,6 +77,7 @@ public static void ContextWithAllOptionsSet_GeneratesExpectedOptions()
                 PropertyNameCaseInsensitive = true,
                 PropertyNamingPolicy = JsonNamingPolicy.KebabCaseUpper,
                 ReadCommentHandling = JsonCommentHandling.Skip,
+                ReferenceHandler = ReferenceHandler.Preserve,
                 RespectNullableAnnotations = true,
                 RespectRequiredConstructorParameters = true,
                 UnknownTypeHandling = JsonUnknownTypeHandling.JsonNode,
@@ -110,6 +111,7 @@ public static void ContextWithAllOptionsSet_GeneratesExpectedOptions()
             PropertyNameCaseInsensitive = true,
             PropertyNamingPolicy = JsonKnownNamingPolicy.KebabCaseUpper,
             ReadCommentHandling = JsonCommentHandling.Skip,
+            ReferenceHandler = JsonKnownReferenceHandler.Preserve,
             RespectNullableAnnotations = true,
             RespectRequiredConstructorParameters = true,
             UnknownTypeHandling = JsonUnknownTypeHandling.JsonNode,