typedefRequiredPositional property

SCD137 — the positional arity of the FUNCTION TYPEDEF this bridge stands for, when it stands for one. null on every other bridge, and on a typedef bridge generated before the generator carried the signature through — in which case FunctionRuntimeType.isSubtypeOf keeps scd136's arity-blind acceptance.

A function typedef has no bridgeable class, so it is registered as BridgedClass(nativeType: Function, name: typedef.name). That discarded the signature, which is why VoidCallback and ValueChanged were indistinguishable to the interpreter.

Only POSITIONAL arity is carried, and only these two numbers. Return types are deliberately absent: an interpreted closure always resolves to dynamic Function(...), so checking returns would refuse working callbacks wholesale.