problem with new translation component config in BETA2

[craigh]

Symfony version(s) affected: 5.2.0-BETA2

Description
new php configuration changes the #3 argument from

        <argument type="collection" /> <!-- translation loaders ids -->

to

            abstract_arg('translation loaders ids'),

This causes problems with (at least) willdurand/BazingaJsTranslationBundle because they use a compiler pass that pulls the #3 argument and assumes it is an array then uses array_merge() with that arg.

How to reproduce
What I did was upgrade my working project from symfony 5.1.x to 5.2.0-BETA2 and ran my tests. It fails for the reason above. I know this is not a very reproducible bug and I don't have a better idea to made it reproducible.

Possible Solution
could \Symfony\Component\DependencyInjection\Argument\AbstractArgument be made iterable? not sure that would solve the problem though. Mabe have the default arg be an empty array instead? I don't know what the old collection argument type default value is.

refs willdurand/BazingaJsTranslationBundle#291

[craigh]

I'm sure it would be incorrect to do so, but for argument sake, if I change

        ->args([
            abstract_arg('translation loaders locator'),
            service('translator.formatter'),
            param('kernel.default_locale'),
            abstract_arg('translation loaders ids'),
            [
                'cache_dir' => param('kernel.cache_dir').'/translations',
                'debug' => param('kernel.debug'),
            ],
            abstract_arg('enabled locales'),
        ])

to this

        ->args([
            abstract_arg('translation loaders locator'),
            service('translator.formatter'),
            param('kernel.default_locale'),
            [],
            [
                'cache_dir' => param('kernel.cache_dir').'/translations',
                'debug' => param('kernel.debug'),
            ],
            abstract_arg('enabled locales'),
        ])

then it works correctly for me.