spread-discriminated-model

Id

@azure-tools/typespec-azure-core/spread-discriminated-model

Check a model with a discriminator has not been used in composition.

A model using @discriminator is meant to be used in a polymorphic context. It should be extended to represent the relation. Spreading this model is a sign that either the @discriminator decorator is unnecessary or that model extends should have been used instead.

Impact

• Area: SDK

Spreading a discriminated model silently drops the discriminator, which is usually a mistake.

❌ Incorrect

@discriminator("kind")
model Pet {
  kind: string;
}

model Cat {
  ...Pet;
  meow: boolean;
}

✅ Correct

model Pet {
  kind: string;
}

model Cat {
  ...Pet;
  meow: boolean;
}

@discriminator("kind")
model Pet {
  kind: string;
}

model Cat extends Pet {
  kind: "cat";
  meow: boolean;
}

Suppression

Suppress only when intended (unlikely); only spread non-discriminated types.