BSK-E0086 error

Multiple TypeVarTuple unpacks in generic or tuple type

Only a single TypeVarTuple unpack (*Ts) may appear in a type parameter list or in a tuple... type expression.

# BAD — multiple TypeVarTuples in class
class Array3(Generic[*Ts1, *Ts2]):  # E
    ...

# BAD — multiple unpacks in tuple type
TA5 = tuple[T1, *Ts, T2, *Ts]  # E
TA6 = tuple[T1, *Ts, T2, *tuple[int, ...]]  # E

# GOOD
class Array(Generic[*Ts]): ...
TA1 = tuple[*Ts, T1, T2]  # OK — single unpack

How to handle it

Every rule is on by default — strict is the default, not a cage. You can dial BSK-E0086 down per-file or per-path from your editor or pyproject.toml, or fix the code so it type-checks. See the Type System rules and the complete diagnostic reference.

Canonical URL: https://www.basilisk-python.dev/errors/BSK-E0086