no-case-mismatch

Id

@azure-tools/typespec-azure-core/no-case-mismatch

Validate that no two types have the same name with different casing.

Validate that no two types have the same name with different casing. Having types that differ only by casing can cause issues in case-insensitive languages and is generally confusing. This applies to models, enums, and unions.

Note

Template instances are not checked by this rule since they are not distinct type declarations.

Impact

• Area: SDK

Type names that differ only by casing cannot be generated into most SDK languages.

❌ Incorrect

Two models that differ only by casing:

model FailOverProperties {
  priority: int32;
}

model FailoverProperties {
  priority: int32;
}

Multiple types with case variations:

model FailOverProperties {}
model FailoverProperties {}
model Failoverproperties {}

✅ Correct

Types with meaningfully different names:

model FailedOver {
  status: string;
}

model FailOver {
  priority: int32;
}

Suppression

Suppress only if the API somehow allows it, and then rename the types with client SDK decorators. Otherwise make type names unique when compared case-insensitively.