Function best_base

crates/vm/src/builtins/type.rs:2887–2920

(bases: &'a [PyTypeRef], vm: &VirtualMachine)

}

fn best_base<'a>(bases: &'a [PyTypeRef], vm: &VirtualMachine) -> PyResult<&'a Py<PyType>> {
    let mut base: Option<&Py<PyType>> = None;
    let mut winner: Option<&Py<PyType>> = None;

    for base_i in bases {
        // if !base_i.fast_issubclass(vm.ctx.types.type_type) {
        //     println!("base_i type : {}", base_i.name());
        //     return Err(vm.new_type_error("best must be types".into()));
        // }

        if !base_i.slots.flags.has_feature(PyTypeFlags::BASETYPE) {
            return Err(vm.new_type_error(format!(
                "type '{}' is not an acceptable base type",
                base_i.slot_name()
            )));
        }

        let candidate = solid_base(base_i, vm);
        if winner.is_none() {
            winner = Some(candidate);
            base = Some(base_i.deref());
        } else if winner.unwrap().fast_issubclass(candidate) {
            // Do nothing
        } else if candidate.fast_issubclass(winner.unwrap()) {
            winner = Some(candidate);
            base = Some(base_i.deref());
        } else {
            return Err(vm.new_type_error("multiple bases have instance layout conflict"));
        }
    }

    debug_assert!(base.is_some());
    Ok(base.unwrap())
}

/// Apply Python name mangling for private attributes.
/// `__x` becomes `_ClassName__x` if inside a class.