functionParameters

pub fn functionParameters(self: Type, builder: *const Builder) []const Type {
    const item = builder.type_items.items[@intFromEnum(self)];
    switch (item.tag) {
        .function,
        .vararg_function,
        => {
            var extra = builder.typeExtraDataTrail(Type.Function, item.data);
            return extra.trail.next(extra.data.params_len, Type, builder);
        },
        else => unreachable,
    }
}