Wrong error message for dependency problem in container

[emil-nasso]

• Laravel Version: v5.8.7
• PHP Version: 7.3
• Database Driver & Version: -

Description:

I ran into a situation where the container gives me an error message pointing me in the wrong direction. In the scenario, there are two dependencies that have strings as arguments to the constructor. One of the dependencies are declared with a contextual binding ( a when-call) but the other one is not.

The container gives me the following error message in the example below: Unresolvable dependency resolving [Parameter #0 [ <required> string $a ]] in class App\Console\Commands\Secondary. This dependency is not unresolvable as it has been declared.

I would expect the error message to instead be: Unresolvable dependency resolving [Parameter #0 [ <required> string $c ]] in class App\Console\Commands\DeepTwo. Adding

Declaring DeepTwo as a singleton solves the problem, making Main resolvable via the container.

The problem only seems to occur when the contructor argument in DeepOne has a default value. If I remove the = null i get the correct error message from the container.

Please let me know if this is not reproducible or if I can help in any other way.

Steps To Reproduce:

Run this as a command:

<?php

namespace App\Console\Commands;

use Illuminate\Console\Command;
use Illuminate\Container\Container;

class Main
{
    public function __construct(DeepOne $deepOne, Secondary $secondary)
    { }
}

class DeepOne
{
    // Removing the `= null` in here will result in the correct error-message
   // being shown.
    public function __construct(DeepTwo $c = null)
    { }
}

class DeepTwo
{
    public function __construct(string $a)
    { }
}

class Secondary
{
    public function __construct(string $a, string $b)
    { }
}

class ContainerBug extends Command
{
    protected $signature = 'bug:demo';
    protected $description = 'Container bug demonstration';

    public function handle()
    {
        $container = Container::getInstance();


        $container->when(Main::class)
            ->needs(Secondary::class)
            ->give(function () {
                return new Secondary('a', 'b');
            });

        // Uncommenting this resolves the unresolved dependency
        // $container->singleton(DeepTwo::class, function () {
        //     return new DeepTwo('a');
        // });

        $res  = $container->make(Main::class);

        $this->info('done, without errors');
    }
}

[driesvints]

This indeed seems like a bug to me. Thanks for reporting. Appreciating any help with figuring this out.