Function call 

pub fn call(
    out: &mut Func,
    block: Block,
    made: &Calling<'_>,
    conv: &CallRegs,
    names: &mut Interner,
) -> Result<Made, Refused>

Builds one call: what it passes, what comes back, and what it destroys.

Errors

The first value this cannot pass, and why, before anything is written. A call with one is reported rather than compiled, because the alternative is a call that leaves an argument wherever the last one happened to put a register.