Fix primitive converters to honor JsonNumberHandling when obtained via GetConverter

[Copilot]

Fixed an issue where primitive number converters obtained via JsonSerializerOptions.GetConverter(Type) did not honor the NumberHandling setting when their public Read() and Write() methods were called directly.

Root Cause

When users called GetConverter() to obtain a converter and then directly invoked its Read() or Write() methods, the converter would not respect the JsonSerializerOptions.NumberHandling setting. This was because the public methods were directly calling reader methods like GetInt32() without checking the options.

Solution

Updated all numeric primitive converters to check JsonSerializerOptions.NumberHandling in their public Read() and Write() methods:

• If NumberHandling is not Strict, delegate to the internal ReadNumberWithCustomHandling() / WriteNumberWithCustomHandling() methods
• Otherwise, use the original fast path

Changes Made

Affected converters:

• Integer types: ByteConverter, SByteConverter, Int16Converter, Int32Converter, Int64Converter, Int128Converter, UInt16Converter, UInt32Converter, UInt64Converter, UInt128Converter
• Floating-point types: HalfConverter, SingleConverter, DoubleConverter, DecimalConverter

Fixed infinite recursion:

• Updated Int128Converter, UInt128Converter, and HalfConverter to call ReadCore() directly instead of recursing back to Read()

Fixed test precision issue:

• Changed Single/float test values from 123.45f to 123.5f to use exactly representable floating-point values, ensuring consistent behavior across .NET Framework and .NET Core/.NET

Testing

Added comprehensive test coverage for all 14 modified primitive types:

Read tests (AllowReadingFromString):

• All integer types: byte, sbyte, short, int, long, ushort, uint, ulong
• All floating-point types: float, double, decimal
• NET-only types: Int128, UInt128, Half

Write tests (WriteAsString):

• byte, int, long, ulong, float, decimal

Special value tests (AllowNamedFloatingPointLiterals):

• float, double, Half (NaN handling)

Test Results:

• ✅ 44 GetConverter-specific tests (all passing in reflection mode)
• ✅ All tests properly skip in source generation scenarios (GetConverter requires reflection)
• ✅ All 747 NumberHandling tests pass in reflection mode
• ✅ All 386 NumberHandling tests pass in source generation mode
• ✅ Full System.Text.Json test suite (49,656 tests) passes with no regressions
• ✅ Tests pass consistently on both .NET Framework and .NET Core/.NET

Original prompt

---

This section details on the original issue you should resolve

<issue_title>System.Text.Json - Generic converter type creation does not honour JsonNumberHandling preferences</issue_title>
<issue_description>### Description

When using the JsonSerializerOptions.GetConverter(Type) method to generate generic converter types within JsonConverterFactory etc. it would appear that the JsonConverter created does not honour the underlying JsonSerializerOptions.NumberHandling preferences.

This can be most problematic when trying to have a factory for types such as generic collections where you might want to handle numbers that come from both int or string types.

Instead what happens is that InvalidOperationException - Cannot get the value of a token type 'String' as a number. gets thrown and you need to handle this exception with fallback behaviour

Reproduction Steps

public void GenericTypeConverterFunctionsAsExpected()
    {
        var options = new JsonSerializerOptions() { NumberHandling = JsonNumberHandling.AllowReadingFromString };
        var converter = (JsonConverter<int>)options.GetConverter(typeof(int));
        ReadOnlySpan<byte> jsonReadOnlySpan = "{\"x\": \"123\"}"u8;
        var reader = new Utf8JsonReader(jsonReadOnlySpan);
        reader.Read(); // StartObject
        reader.Read(); // PropertyName
        reader.Read(); // Number
        var x = converter.Read(ref reader, typeof(int), options);
        x.Should().Be(123); // this throws InvalidOperationException
    }

Expected behavior

I would expect because the options being used to generate the converter has the NumberHandling set as AllowReadingFromString then the converter generated (in this case Int32Converter) to correctly handle string based numbers in the json payload.

Actual behavior

And InvalidOperationException excpetion is thrown with the error message Cannot get the value of a token type 'String' as a number. gets thrown and you need to handle this exception with fallback behaviour.

Looking into the logic for the converter here it would appear that the base JsonPrimitiveConverter is not correctly persisting the state to the converter and therefore not invoking ReadNumberWithCustomHandling

Regression?

Unsure

Known Workarounds

A possible workaround is to just use standard JsonSerializer.Deserialize techniques however this is not as performant given I have a locally persisted converter as documented here in the documentation for Factory patterns

try
{
    var element = _valueConverter.Read(ref reader, typeof(T), options);
    if (element != null) list.Add(element);
}
catch (Exception ex) when (ex is JsonException or InvalidOperationException)
{
    // try again but will be less performant sadly :(
    // this covers edge cases where the Number is in quotes for example
    try
    {
        var element = JsonSerializer.Deserialize<T>(ref reader, options);
        if (element != null) list.Add(element);
    }
    catch (Exception) when (ex is JsonException or InvalidOperationException)
    {
        // do nothing, skip invalid element
    }

Configuration

NET8 using System.Text.Json v9.0.10

Other information

No response</issue_description>

<agent_instructions>The Write and Read methods of the primitive converters should try to take number handling configuration present in the JsonSerializerOptions into account.</agent_instructions>

Comments on the Issue (you are @copilot in this section)

@eiriktsarpalis > Looking into the logic for the [converter here](https://github.com/dotnet/runtime/blob/e6fbfa2be5d9f333474fc9f1d71dc2762b26f0af/src/libraries/System.Text.Json/src/System/Text/Json/Serialization/Converters/Value/Int32Converter.cs#L39) it would appear that the base `JsonPrimitiveConverter` is not correctly persisting the state to the converter and therefore not invoking `ReadNumberWithCustomHandling`

The original designers of STJ went intentionally with this approach which is why the Write/ReadNumberWithCustomHandling methods exist. I suspect the motivation was related to performance when number handling isn't turned on, but it's conceivable we could try to make this behave more uniformly provided the performance regressions aren't significant.

EDIT: Actually, it turns out that the internal methods are essential since the public Write/Read methods aren't passing the necessary context needed to determine the number handling of the present property.</comment_new>

Fixes #120798

---

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[stephentoub]

@copilot, there are test failures:

  Discovering: System.Text.Json.SourceGeneration.Roslyn4.4.Tests (method display = ClassAndMethod, method display options = None)
  Discovered:  System.Text.Json.SourceGeneration.Roslyn4.4.Tests (found 4007 of 4063 test cases)
  Starting:    System.Text.Json.SourceGeneration.Roslyn4.4.Tests (parallel test collections = on [2 threads], stop on fail = off)
    System.Text.Json.SourceGeneration.Tests.NumberHandlingTests_Default.GetConverter_Int32_RespectsNumberHandling_AllowReadingFromString [FAIL]
      System.NotSupportedException : JsonTypeInfo metadata for type 'System.Int32' was not provided by TypeInfoResolver of type '<null>'. If using source generation, ensure that all root types passed to the serializer have been annotated with 'JsonSerializableAttribute', along with any types that might be serialized polymorphically.
      Stack Trace:
        /_/src/libraries/System.Text.Json/src/System/Text/Json/ThrowHelper.Serialization.cs(855,0): at System.Text.Json.ThrowHelper.ThrowNotSupportedException_NoMetadataForType(Type type, IJsonTypeInfoResolver resolver)
        /_/src/libraries/System.Text.Json/src/System/Text/Json/Serialization/JsonSerializerOptions.Caching.cs(126,0): at System.Text.Json.JsonSerializerOptions.GetTypeInfoInternal(Type type, Boolean ensureConfigured, Nullable`1 ensureNotNull, Boolean resolveIfMutable, Boolean fallBackToNearestAncestorType)
        /_/src/libraries/System.Text.Json/src/System/Text/Json/Serialization/JsonSerializerOptions.Converters.cs(63,0): at System.Text.Json.JsonSerializerOptions.GetConverterInternal(Type typeToConvert)
        /_/src/libraries/System.Text.Json/src/System/Text/Json/Serialization/JsonSerializerOptions.Converters.cs(55,0): at System.Text.Json.JsonSerializerOptions.GetConverter(Type typeToConvert)
        /_/src/libraries/System.Text.Json/tests/Common/NumberHandlingTests.cs(2015,0): at System.Text.Json.Serialization.Tests.NumberHandlingTests.GetConverter_Int32_RespectsNumberHandling_AllowReadingFromString()
           at System.RuntimeMethodHandle.InvokeMethod(ObjectHandleOnStack target, Void** arguments, ObjectHandleOnStack sig, BOOL isConstructor, ObjectHandleOnStack result)
           at System.RuntimeMethodHandle.InvokeMethod(ObjectHandleOnStack target, Void** arguments, ObjectHandleOnStack sig, BOOL isConstructor, ObjectHandleOnStack result)
        /_/src/coreclr/System.Private.CoreLib/src/System/RuntimeHandles.cs(1165,0): at System.RuntimeMethodHandle.InvokeMethod(Object target, Void** arguments, Signature sig, Boolean isConstructor)
        /_/src/coreclr/System.Private.CoreLib/src/System/Reflection/MethodBaseInvoker.CoreCLR.cs(36,0): at System.Reflection.MethodBaseInvoker.InterpretedInvoke_Method(Object obj, IntPtr* args)
        /_/src/libraries/System.Private.CoreLib/src/System/Reflection/MethodBaseInvoker.cs(57,0): at System.Reflection.MethodBaseInvoker.InvokeWithNoArgs(Object obj, BindingFlags invokeAttr)
    System.Text.Json.SourceGeneration.Tests.NumberHandlingTests_Default.GetConverter_Double_RespectsNumberHandling_AllowReadingFromString [FAIL]
      System.NotSupportedException : JsonTypeInfo metadata for type 'System.Double' was not provided by TypeInfoResolver of type '<null>'. If using source generation, ensure that all root types passed to the serializer have been annotated with 'JsonSerializableAttribute', along with any types that might be serialized polymorphically.
      Stack Trace:
        /_/src/libraries/System.Text.Json/src/System/Text/Json/ThrowHelper.Serialization.cs(855,0): at System.Text.Json.ThrowHelper.ThrowNotSupportedException_NoMetadataForType(Type type, IJsonTypeInfoResolver resolver)
        /_/src/libraries/System.Text.Json/src/System/Text/Json/Serialization/JsonSerializerOptions.Caching.cs(126,0): at System.Text.Json.JsonSerializerOptions.GetTypeInfoInternal(Type type, Boolean ensureConfigured, Nullable`1 ensureNotNull, Boolean resolveIfMutable, Boolean fallBackToNearestAncestorType)
        /_/src/libraries/System.Text.Json/src/System/Text/Json/Serialization/JsonSerializerOptions.Converters.cs(63,0): at System.Text.Json.JsonSerializerOptions.GetConverterInternal(Type typeToConvert)
        /_/src/libraries/System.Text.Json/src/System/Text/Json/Serialization/JsonSerializerOptions.Converters.cs(55,0): at System.Text.Json.JsonSerializerOptions.GetConverter(Type typeToConvert)
        /_/src/libraries/System.Text.Json/tests/Common/NumberHandlingTests.cs(2045,0): at System.Text.Json.Serialization.Tests.NumberHandlingTests.GetConverter_Double_RespectsNumberHandling_AllowReadingFromString()
           at System.RuntimeMethodHandle.InvokeMethod(ObjectHandleOnStack target, Void** arguments, ObjectHandleOnStack sig, BOOL isConstructor, ObjectHandleOnStack result)
           at System.RuntimeMethodHandle.InvokeMethod(ObjectHandleOnStack target, Void** arguments, ObjectHandleOnStack sig, BOOL isConstructor, ObjectHandleOnStack result)
        /_/src/coreclr/System.Private.CoreLib/src/System/RuntimeHandles.cs(1165,0): at System.RuntimeMethodHandle.InvokeMethod(Object target, Void** arguments, Signature sig, Boolean isConstructor)
        /_/src/coreclr/System.Private.CoreLib/src/System/Reflection/MethodBaseInvoker.CoreCLR.cs(36,0): at System.Reflection.MethodBaseInvoker.InterpretedInvoke_Method(Object obj, IntPtr* args)
        /_/src/libraries/System.Private.CoreLib/src/System/Reflection/MethodBaseInvoker.cs(57,0): at System.Reflection.MethodBaseInvoker.InvokeWithNoArgs(Object obj, BindingFlags invokeAttr)
    System.Text.Json.SourceGeneration.Tests.NumberHandlingTests_Default.GetConverter_Int32_RespectsNumberHandling_WriteAsString [FAIL]
      System.NotSupportedException : JsonTypeInfo metadata for type 'System.Int32' was not provided by TypeInfoResolver of type '<null>'. If using source generation, ensure that all root types passed to the serializer have been annotated with 'JsonSerializableAttribute', along with any types that might be serialized polymorphically.
      Stack Trace:
        /_/src/libraries/System.Text.Json/src/System/Text/Json/ThrowHelper.Serialization.cs(855,0): at System.Text.Json.ThrowHelper.ThrowNotSupportedException_NoMetadataForType(Type type, IJsonTypeInfoResolver resolver)
        /_/src/libraries/System.Text.Json/src/System/Text/Json/Serialization/JsonSerializerOptions.Caching.cs(126,0): at System.Text.Json.JsonSerializerOptions.GetTypeInfoInternal(Type type, Boolean ensureConfigured, Nullable`1 ensureNotNull, Boolean resolveIfMutable, Boolean fallBackToNearestAncestorType)
        /_/src/libraries/System.Text.Json/src/System/Text/Json/Serialization/JsonSerializerOptions.Converters.cs(63,0): at System.Text.Json.JsonSerializerOptions.GetConverterInternal(Type typeToConvert)
        /_/src/libraries/System.Text.Json/src/System/Text/Json/Serialization/JsonSerializerOptions.Converters.cs(55,0): at System.Text.Json.JsonSerializerOptions.GetConverter(Type typeToConvert)
        /_/src/libraries/System.Text.Json/tests/Common/NumberHandlingTests.cs(2029,0): at System.Text.Json.Serialization.Tests.NumberHandlingTests.GetConverter_Int32_RespectsNumberHandling_WriteAsString()
           at System.RuntimeMethodHandle.InvokeMethod(ObjectHandleOnStack target, Void** arguments, ObjectHandleOnStack sig, BOOL isConstructor, ObjectHandleOnStack result)
           at System.RuntimeMethodHandle.InvokeMethod(ObjectHandleOnStack target, Void** arguments, ObjectHandleOnStack sig, BOOL isConstructor, ObjectHandleOnStack result)
        /_/src/coreclr/System.Private.CoreLib/src/System/RuntimeHandles.cs(1165,0): at System.RuntimeMethodHandle.InvokeMethod(Object target, Void** arguments, Signature sig, Boolean isConstructor)
        /_/src/coreclr/System.Private.CoreLib/src/System/Reflection/MethodBaseInvoker.CoreCLR.cs(36,0): at System.Reflection.MethodBaseInvoker.InterpretedInvoke_Method(Object obj, IntPtr* args)
        /_/src/libraries/System.Private.CoreLib/src/System/Reflection/MethodBaseInvoker.cs(57,0): at System.Reflection.MethodBaseInvoker.InvokeWithNoArgs(Object obj, BindingFlags invokeAttr)
    System.Text.Json.SourceGeneration.Tests.NumberHandlingTests_Default.GetConverter_Double_RespectsNumberHandling_AllowNamedFloatingPointLiterals [FAIL]
      System.NotSupportedException : JsonTypeInfo metadata for type 'System.Double' was not provided by TypeInfoResolver of type '<null>'. If using source generation, ensure that all root types passed to the serializer have been annotated with 'JsonSerializableAttribute', along with any types that might be serialized polymorphically.
      Stack Trace:
        /_/src/libraries/System.Text.Json/src/System/Text/Json/ThrowHelper.Serialization.cs(855,0): at System.Text.Json.ThrowHelper.ThrowNotSupportedException_NoMetadataForType(Type type, IJsonTypeInfoResolver resolver)
        /_/src/libraries/System.Text.Json/src/System/Text/Json/Serialization/JsonSerializerOptions.Caching.cs(126,0): at System.Text.Json.JsonSerializerOptions.GetTypeInfoInternal(Type type, Boolean ensureConfigured, Nullable`1 ensureNotNull, Boolean resolveIfMutable, Boolean fallBackToNearestAncestorType)
        /_/src/libraries/System.Text.Json/src/System/Text/Json/Serialization/JsonSerializerOptions.Converters.cs(63,0): at System.Text.Json.JsonSerializerOptions.GetConverterInternal(Type typeToConvert)
        /_/src/libraries/System.Text.Json/src/System/Text/Json/Serialization/JsonSerializerOptions.Converters.cs(55,0): at System.Text.Json.JsonSerializerOptions.GetConverter(Type typeToConvert)
        /_/src/libraries/System.Text.Json/tests/Common/NumberHandlingTests.cs(2059,0): at System.Text.Json.Serialization.Tests.NumberHandlingTests.GetConverter_Double_RespectsNumberHandling_AllowNamedFloatingPointLiterals()
           at System.RuntimeMethodHandle.InvokeMethod(ObjectHandleOnStack target, Void** arguments, ObjectHandleOnStack sig, BOOL isConstructor, ObjectHandleOnStack result)
           at System.RuntimeMethodHandle.InvokeMethod(ObjectHandleOnStack target, Void** arguments, ObjectHandleOnStack sig, BOOL isConstructor, ObjectHandleOnStack result)
        /_/src/coreclr/System.Private.CoreLib/src/System/RuntimeHandles.cs(1165,0): at System.RuntimeMethodHandle.InvokeMethod(Object target, Void** arguments, Signature sig, Boolean isConstructor)
        /_/src/coreclr/System.Private.CoreLib/src/System/Reflection/MethodBaseInvoker.CoreCLR.cs(36,0): at System.Reflection.MethodBaseInvoker.InterpretedInvoke_Method(Object obj, IntPtr* args)
        /_/src/libraries/System.Private.CoreLib/src/System/Reflection/MethodBaseInvoker.cs(57,0): at System.Reflection.MethodBaseInvoker.InvokeWithNoArgs(Object obj, BindingFlags invokeAttr)
    System.Text.Json.SourceGeneration.Tests.NumberHandlingTests_Metadata.GetConverter_Double_RespectsNumberHandling_AllowReadingFromString [FAIL]
      System.NotSupportedException : JsonTypeInfo metadata for type 'System.Double' was not provided by TypeInfoResolver of type '<null>'. If using source generation, ensure that all root types passed to the serializer have been annotated with 'JsonSerializableAttribute', along with any types that might be serialized polymorphically.
      Stack Trace:
        /_/src/libraries/System.Text.Json/src/System/Text/Json/ThrowHelper.Serialization.cs(855,0): at System.Text.Json.ThrowHelper.ThrowNotSupportedException_NoMetadataForType(Type type, IJsonTypeInfoResolver resolver)
        /_/src/libraries/System.Text.Json/src/System/Text/Json/Serialization/JsonSerializerOptions.Caching.cs(126,0): at System.Text.Json.JsonSerializerOptions.GetTypeInfoInternal(Type type, Boolean ensureConfigured, Nullable`1 ensureNotNull, Boolean resolveIfMutable, Boolean fallBackToNearestAncestorType)
        /_/src/libraries/System.Text.Json/src/System/Text/Json/Serialization/JsonSerializerOptions.Converters.cs(63,0): at System.Text.Json.JsonSerializerOptions.GetConverterInternal(Type typeToConvert)
        /_/src/libraries/System.Text.Json/src/System/Text/Json/Serialization/JsonSerializerOptions.Converters.cs(55,0): at System.Text.Json.JsonSerializerOptions.GetConverter(Type typeToConvert)
        /_/src/libraries/System.Text.Json/tests/Common/NumberHandlingTests.cs(2045,0): at System.Text.Json.Serialization.Tests.NumberHandlingTests.GetConverter_Double_RespectsNumberHandling_AllowReadingFromString()
           at System.RuntimeMethodHandle.InvokeMethod(ObjectHandleOnStack target, Void** arguments, ObjectHandleOnStack sig, BOOL isConstructor, ObjectHandleOnStack result)
           at System.RuntimeMethodHandle.InvokeMethod(ObjectHandleOnStack target, Void** arguments, ObjectHandleOnStack sig, BOOL isConstructor, ObjectHandleOnStack result)
        /_/src/coreclr/System.Private.CoreLib/src/System/RuntimeHandles.cs(1165,0): at System.RuntimeMethodHandle.InvokeMethod(Object target, Void** arguments, Signature sig, Boolean isConstructor)
        /_/src/coreclr/System.Private.CoreLib/src/System/Reflection/MethodBaseInvoker.CoreCLR.cs(36,0): at System.Reflection.MethodBaseInvoker.InterpretedInvoke_Method(Object obj, IntPtr* args)
        /_/src/libraries/System.Private.CoreLib/src/System/Reflection/MethodBaseInvoker.cs(57,0): at System.Reflection.MethodBaseInvoker.InvokeWithNoArgs(Object obj, BindingFlags invokeAttr)
    System.Text.Json.SourceGeneration.Tests.NumberHandlingTests_Metadata.GetConverter_Double_RespectsNumberHandling_AllowNamedFloatingPointLiterals [FAIL]
      System.NotSupportedException : JsonTypeInfo metadata for type 'System.Double' was not provided by TypeInfoResolver of type '<null>'. If using source generation, ensure that all root types passed to the serializer have been annotated with 'JsonSerializableAttribute', along with any types that might be serialized polymorphically.
      Stack Trace:
        /_/src/libraries/System.Text.Json/src/System/Text/Json/ThrowHelper.Serialization.cs(855,0): at System.Text.Json.ThrowHelper.ThrowNotSupportedException_NoMetadataForType(Type type, IJsonTypeInfoResolver resolver)
        /_/src/libraries/System.Text.Json/src/System/Text/Json/Serialization/JsonSerializerOptions.Caching.cs(126,0): at System.Text.Json.JsonSerializerOptions.GetTypeInfoInternal(Type type, Boolean ensureConfigured, Nullable`1 ensureNotNull, Boolean resolveIfMutable, Boolean fallBackToNearestAncestorType)
        /_/src/libraries/System.Text.Json/src/System/Text/Json/Serialization/JsonSerializerOptions.Converters.cs(63,0): at System.Text.Json.JsonSerializerOptions.GetConverterInternal(Type typeToConvert)
        /_/src/libraries/System.Text.Json/src/System/Text/Json/Serialization/JsonSerializerOptions.Converters.cs(55,0): at System.Text.Json.JsonSerializerOptions.GetConverter(Type typeToConvert)
        /_/src/libraries/System.Text.Json/tests/Common/NumberHandlingTests.cs(2059,0): at System.Text.Json.Serialization.Tests.NumberHandlingTests.GetConverter_Double_RespectsNumberHandling_AllowNamedFloatingPointLiterals()
           at System.RuntimeMethodHandle.InvokeMethod(ObjectHandleOnStack target, Void** arguments, ObjectHandleOnStack sig, BOOL isConstructor, ObjectHandleOnStack result)
        /_/src/libraries/System.Private.CoreLib/src/System/Reflection/RuntimeMethodInfo.cs(126,0): at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
    System.Text.Json.SourceGeneration.Tests.NumberHandlingTests_Metadata.GetConverter_Int32_RespectsNumberHandling_AllowReadingFromString [FAIL]
      System.NotSupportedException : JsonTypeInfo metadata for type 'System.Int32' was not provided by TypeInfoResolver of type '<null>'. If using source generation, ensure that all root types passed to the serializer have been annotated with 'JsonSerializableAttribute', along with any types that might be serialized polymorphically.
      Stack Trace:
        /_/src/libraries/System.Text.Json/src/System/Text/Json/ThrowHelper.Serialization.cs(855,0): at System.Text.Json.ThrowHelper.ThrowNotSupportedException_NoMetadataForType(Type type, IJsonTypeInfoResolver resolver)
        /_/src/libraries/System.Text.Json/src/System/Text/Json/Serialization/JsonSerializerOptions.Caching.cs(126,0): at System.Text.Json.JsonSerializerOptions.GetTypeInfoInternal(Type type, Boolean ensureConfigured, Nullable`1 ensureNotNull, Boolean resolveIfMutable, Boolean fallBackToNearestAncestorType)
        /_/src/libraries/System.Text.Json/src/System/Text/Json/Serialization/JsonSerializerOptions.Converters.cs(63,0): at System.Text.Json.JsonSerializerOptions.GetConverterInternal(Type typeToConvert)
        /_/src/libraries/System.Text.Json/src/System/Text/Json/Serialization/JsonSerializerOptions.Converters.cs(55,0): at System.Text.Json.JsonSerializerOptions.GetConverter(Type typeToConvert)
        /_/src/libraries/System.Text.Json/tests/Common/NumberHandlingTests.cs(2015,0): at System.Text.Json.Serialization.Tests.NumberHandlingTests.GetConverter_Int32_RespectsNumberHandling_AllowReadingFromString()
           at System.RuntimeMethodHandle.InvokeMethod(ObjectHandleOnStack target, Void** arguments, ObjectHandleOnStack sig, BOOL isConstructor, ObjectHandleOnStack result)
        /_/src/libraries/System.Private.CoreLib/src/System/Reflection/RuntimeMethodInfo.cs(126,0): at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
    System.Text.Json.SourceGeneration.Tests.NumberHandlingTests_Metadata.GetConverter_Int32_RespectsNumberHandling_WriteAsString [FAIL]
      System.NotSupportedException : JsonTypeInfo metadata for type 'System.Int32' was not provided by TypeInfoResolver of type '<null>'. If using source generation, ensure that all root types passed to the serializer have been annotated with 'JsonSerializableAttribute', along with any types that might be serialized polymorphically.
      Stack Trace:
        /_/src/libraries/System.Text.Json/src/System/Text/Json/ThrowHelper.Serialization.cs(855,0): at System.Text.Json.ThrowHelper.ThrowNotSupportedException_NoMetadataForType(Type type, IJsonTypeInfoResolver resolver)
        /_/src/libraries/System.Text.Json/src/System/Text/Json/Serialization/JsonSerializerOptions.Caching.cs(126,0): at System.Text.Json.JsonSerializerOptions.GetTypeInfoInternal(Type type, Boolean ensureConfigured, Nullable`1 ensureNotNull, Boolean resolveIfMutable, Boolean fallBackToNearestAncestorType)
        /_/src/libraries/System.Text.Json/src/System/Text/Json/Serialization/JsonSerializerOptions.Converters.cs(63,0): at System.Text.Json.JsonSerializerOptions.GetConverterInternal(Type typeToConvert)
        /_/src/libraries/System.Text.Json/src/System/Text/Json/Serialization/JsonSerializerOptions.Converters.cs(55,0): at System.Text.Json.JsonSerializerOptions.GetConverter(Type typeToConvert)
        /_/src/libraries/System.Text.Json/tests/Common/NumberHandlingTests.cs(2029,0): at System.Text.Json.Serialization.Tests.NumberHandlingTests.GetConverter_Int32_RespectsNumberHandling_WriteAsString()
           at System.RuntimeMethodHandle.InvokeMethod(ObjectHandleOnStack target, Void** arguments, ObjectHandleOnStack sig, BOOL isConstructor, ObjectHandleOnStack result)
        /_/src/libraries/System.Private.CoreLib/src/System/Reflection/RuntimeMethodInfo.cs(126,0): at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
  Finished:    System.Text.Json.SourceGeneration.Roslyn4.4.Tests

[Copilot]

@copilot, there are test failures:

  Discovering: System.Text.Json.SourceGeneration.Roslyn4.4.Tests (method display = ClassAndMethod, method display options = None)

...

Fixed in commit cafaf2f. The GetConverter tests now skip in source generation scenarios since GetConverter() requires reflection which isn't available in source-generated contexts.

[dotnet-policy-service]

Tagging subscribers to this area: @dotnet/area-system-text-json, @gregsdennis
See info in area-owners.md if you want to be subscribed.

[eiriktsarpalis]

LGTM, although there is a distinct possibility that this change will regress the STJ microbenchmarks we have in dotnet/performance. We can re-evaluate if and when regression numbers start coming in.

[Copilot]

Pull Request Overview

This PR fixes an issue where primitive number converters obtained via JsonSerializerOptions.GetConverter(Type) did not honor the JsonNumberHandling setting when their public Read() and Write() methods were called directly. The fix adds checks in each converter to delegate to the internal custom handling methods when NumberHandling is not Strict.

Key changes:

• Updated all 14 primitive number converters (integers and floating-point types) to check NumberHandling before proceeding with default behavior
• Fixed infinite recursion issues in Int128Converter, UInt128Converter, and HalfConverter by replacing recursive Read() calls with direct ReadCore() calls
• Added 5 new tests to verify the fix works correctly with GetConverter()

Reviewed Changes

Copilot reviewed 15 out of 15 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
NumberHandlingTests.cs	Added 5 new tests verifying converters obtained via GetConverter respect NumberHandling settings
ByteConverter.cs	Added NumberHandling check to delegate to custom handling methods when needed
SByteConverter.cs	Added NumberHandling check to delegate to custom handling methods when needed
Int16Converter.cs	Added NumberHandling check to delegate to custom handling methods when needed
Int32Converter.cs	Added NumberHandling check to delegate to custom handling methods when needed
Int64Converter.cs	Added NumberHandling check to delegate to custom handling methods when needed
Int128Converter.cs	Added NumberHandling check and fixed infinite recursion in ReadNumberWithCustomHandling
UInt16Converter.cs	Added NumberHandling check to delegate to custom handling methods when needed
UInt32Converter.cs	Added NumberHandling check to delegate to custom handling methods when needed
UInt64Converter.cs	Added NumberHandling check to delegate to custom handling methods when needed
UInt128Converter.cs	Added NumberHandling check and fixed infinite recursion in ReadNumberWithCustomHandling
DecimalConverter.cs	Added NumberHandling check to delegate to custom handling methods when needed
SingleConverter.cs	Added NumberHandling check to delegate to custom handling methods when needed
DoubleConverter.cs	Added NumberHandling check to delegate to custom handling methods when needed
HalfConverter.cs	Added NumberHandling check and fixed infinite recursion in ReadNumberWithCustomHandling

[stephentoub]

@eiriktsarpalis, next steps here?

[eiriktsarpalis]

Let's go ahead and merge. Any noticeable regressions will no doubt get reported by the performance team.

[stephentoub]

@copilot, there's a test failure in CI, but only in the .NET Framework build:

  Discovering: System.Text.Json.Tests (app domain = on [no shadow copy], method display = ClassAndMethod, method display options = None)
  Discovered:  System.Text.Json.Tests (found 10098 of 10170 test cases)
  Starting:    System.Text.Json.Tests (parallel test collections = on [2 threads], stop on fail = off)
    System.Text.Json.Serialization.Tests.NumberHandlingTestsDynamic.GetConverter_Single_RespectsNumberHandling_WriteAsString [FAIL]
      Assert.Equal() Failure: Strings differ
                            ↓ (pos 11)
      Expected: "{"x":"123.45"}"
      Actual:   "{"x":"123.449997"}"
                            ↑ (pos 11)
      Stack Trace:
        /_/src/libraries/System.Text.Json/tests/Common/NumberHandlingTests.cs(2256,0): at System.Text.Json.Serialization.Tests.NumberHandlingTests.GetConverter_Single_RespectsNumberHandling_WriteAsString()

It looks like the test relies on floating points value formatting and that's a bit different between the versions.

[Copilot]

@copilot, there's a test failure in CI, but only in the .NET Framework build:

  Discovering: System.Text.Json.Tests (app domain = on [no shadow copy], method display = ClassAndMethod, method dis...

Fixed in commit (will be shown after push). Changed the test value from 123.45f to 123.5f - the latter is exactly representable in single-precision floating point, avoiding formatting differences between .NET Framework and .NET Core/.NET. Also updated the corresponding Read test for consistency.