legacy-hierarchy-building-circular-reference

Id

@azure-tools/typespec-client-generator-core/legacy-hierarchy-building-circular-reference

Severity: error

This diagnostic is issued when @hierarchyBuilding creates a recursive base-type chain.

Impact

• Area: Legacy SDK inheritance rebasing. Blocks hierarchy rebasing because it would create a circular generated base-model chain.
• Not affected: The original TypeSpec inheritance declarations are unchanged.

❌ Incorrect Usage

@usage(Usage.input)
namespace TestService;

model A extends B {
  propA: string;
}

@hierarchyBuilding(A) // rebasing `B` onto `A` creates a circular base chain
model B extends C {
  propB: string;
}

model C {
  propC: string;
}

Diagnostic Message

TCGC reports:

@hierarchyBuilding decorator causes recursive base type reference.

✅ How to Fix

Remove or change the @hierarchyBuilding decorator so the rebased hierarchy is acyclic.

@usage(Usage.input)
namespace TestService;

model A extends B {
  propA: string;
}

model B extends C {
  propB: string;
}

model C {
  propC: string;
}