Macros defined in parent are considered as not defined

When a macro is defined in a parent template, it is considered as not defined even though it is available in the template:

{% extends "parent.twig" %}

{% block f %}
    {% import _self as s %}

    {{ s.bar() }} // works

    {% if (s.bar is defined) %} // returns false
        TRUE
    {% else %}
        FALSE
    {% endif %}
{% endblock %}

• parent.twig

{% block f %}
{% endblock %}

{% macro bar() %}
BAR
{% endmacro %}

https://twigfiddle.com/ckttfv

This is due to the fact that when calling a macro, parent macros are also considered:

/**
 * @internal
 */
function twig_call_macro(Template $template, string $method, array $args, int $lineno, array $context, Source $source)
{
    if (!method_exists($template, $method)) {
        $parent = $template;
        while ($parent = $parent->getParent($context)) {
            if (method_exists($parent, $method)) {
                return $parent->$method(...$args);
            }
        }

        throw new RuntimeError(sprintf('Macro "%s" is not defined in template "%s".', substr($method, \strlen('macro_')), $template->getTemplateName()), $lineno, $source);
    }

    return $template->$method(...$args);
}

But when a macro is tested for existence (via the is defined test), parent macros are not considered:

if ($this->getAttribute('is_defined_test')) {
            $compiler
                ->raw('method_exists($macros[')
                ->repr($this->getNode('node')->getAttribute('name'))
                ->raw('], ')
                ->repr($this->getAttribute('method'))
                ->raw(')')
            ;

            return;
        }

It looks inconsistent to me. The purpose of the defined test is to ensure that the template can safely call a macro. But it is actually impossible to know if a macro is defined before using it - macros coming from parents will always be considered as not defined even though they are perfectly usable.

Reproduce the parent.twig and child template example, then inspect the twig_call_macro runtime path and the compiler branch handling is_defined_test. Add a regression test covering a macro inherited from a parent and verify that the defined test agrees with the existing callable behavior.