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SHIFT007: Reflection-based activation is not trimming or NativeAOT safe

Property Value
Rule ID SHIFT007
Category ShapeShift.Reliability
Default severity Info
Enabled by default Yes
Code fix None

Cause

Code calls WithReflectionConverterTypes on a ShapeShift serializer, or uses PolyType's ReflectionTypeShapeProvider.

Rule description

ShapeShift's default path — converter instances, converter factories and source-generated type shapes — is free of reflection and safe for trimming and NativeAOT. Two opt-ins step outside that guarantee:

  • WithReflectionConverterTypes activates converter Type objects through reflection, which may need to construct closed generic types at run time.
  • ReflectionTypeShapeProvider derives contracts by reflecting over types instead of using generated shapes.

Both are supported and deliberately explicit, but a trimmed or NativeAOT deployment can fail at run time unless every constructor and member they reach is rooted.

The diagnostic is reported at Info severity so that the opt-in stays visible during review without failing builds that intend to use it.

How to fix violations

Prefer registering converter instances or factories, and source-generated shapes:

// Reflection-based opt-in
JsonSerializer serializer = (JsonSerializer)new JsonSerializer()
    .WithReflectionConverterTypes([typeof(PersonConverter)]);

// NativeAOT-safe
JsonSerializer serializer = new() { Converters = [new PersonConverter()] };

For type shapes, apply [GenerateShape] to your types or declare a [GenerateShapeFor<T>] witness instead of using ReflectionTypeShapeProvider.Default. See SHIFT004.

When to suppress warnings

Suppress this diagnostic in applications that are never trimmed or published as NativeAOT and that deliberately use the reflection opt-in:

dotnet_diagnostic.SHIFT007.severity = none

See also

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