Missing Annotations — E0001–E0009

Rules that flag code where type information is absent.

← All Rules | Next: Type Safety →

BSK-E0001 — Missing parameter type annotation

Every function parameter must have an explicit type annotation.

# Error
def process(data):
    return data.upper()

# Correct
def process(data: str) -> str:
    return data.upper()

BSK-E0002 — Missing return type annotation

Every function must declare its return type.

# Error
def get_user(user_id: int):
    return {"id": user_id}

# Correct
def get_user(user_id: int) -> dict[str, int]:
    return {"id": user_id}

BSK-E0003 — Unresolvable variable type

A variable is assigned a value whose type cannot be inferred. An explicit annotation is required.

# Error — type of result cannot be determined
result = some_dynamic_function()

# Correct
result: list[str] = some_dynamic_function()

BSK-E0004 — Missing *args or **kwargs annotation

Variadic arguments must be annotated.

# Error
def log(*args, **kwargs):
    print(args, kwargs)

# Correct
def log(*args: str, **kwargs: int) -> None:
    print(args, kwargs)

BSK-E0005 — Missing class attribute annotation

Class-level attributes must be explicitly annotated.

# Error
class Config:
    host = "localhost"
    port = 8080

# Correct
class Config:
    host: str = "localhost"
    port: int = 8080