missing-scope

Id

@azure-tools/typespec-client-generator-core/missing-scope

Severity: error

This diagnostic is issued when a decorator that is likely language-specific is used without a language scope; currently this is reported for external @alternateType metadata without a scope.

Impact

• Area: Language-specific alternate-type customization. Blocks external type metadata that lacks a target emitter scope, preventing it from being applied globally by accident.
• Not affected: The TypeSpec type definition and service payload schema are unchanged.

❌ Incorrect Usage

@alternateType({
  // external alternate type is missing a language scope
  identity: "pystac.Collection",

  package: "pystac",
  minVersion: "1.13.0",
})
model ItemCollection {}

Diagnostic Message

TCGC reports:

@scope decorator should be applied with @alternateType since it is highly likely this is language-specific

✅ How to Fix

Provide the appropriate language scope argument, such as "python", "csharp", or another emitter scope:

@alternateType(
  {
    identity: "pystac.Collection",
    package: "pystac",
    minVersion: "1.13.0",
  },
  "python"
)
model ItemCollection {}