[DependencyInjection] #[When(env: 'staging')] throws exception when using dev-only classes

[jon-ht]

Symfony version(s) affected

5.4, 6.3

Description

When I add #[When(env: 'staging')] attribute to a service that should only be used in staging environment, I got an exception about a missing class.

Error: During class fetch: Uncaught ReflectionException: Class "Nelmio\Alice\IsAServiceTrait" not found while loading "App\OnlyAvailableOnStaging". in /srv/app/vendor/symfony/error-handler/DebugClassLoader.php:293
Stack trace:
#0 /srv/app/vendor/symfony/config/Resource/ClassExistenceResource.php(76): class_exists('App\\OnlyAvailab...')
#1 /srv/app/vendor/symfony/dependency-injection/ContainerBuilder.php(361): Symfony\Component\Config\Resource\ClassExistenceResource->isFresh(0)
#2 /srv/app/vendor/symfony/dependency-injection/Loader/FileLoader.php(275): Symfony\Component\DependencyInjection\ContainerBuilder->getReflectionClass('App\\OnlyAvailab...')
#3 /srv/app/vendor/symfony/dependency-injection/Loader/FileLoader.php(121): Symfony\Component\DependencyInjection\Loader\FileLoader->findClasses('App\\', '../src/', Array, Object(Symfony\Component\DependencyInjection\Compiler\RegisterAutoconfigureAttributesPass), '/srv/app/config...')
// ...

That's totally fair, because the trait referenced here (IsAServiceTrait) is only installed in dev environment.

What I don't understand, is that ReflectionException should be caught here

symfony/src/Symfony/Component/DependencyInjection/Loader/FileLoader.php

Lines 292 to 297 in 42d9d7c

	try {
	$r = $this->container->getReflectionClass($class);
	} catch (\ReflectionException $e) {
	$classes[$class] = $e->getMessage();
	continue;
	}

But I never reach this catch block and Symfony\Component\ErrorHandler\ErrorHandler::handleFatalError get called instead

symfony/src/Symfony/Component/ErrorHandler/ErrorHandler.php

Line 569 in 42d9d7c

public static function handleFatalError(array $error = null): void

How to reproduce

This is the minimal reproducer I can get

<?php

declare(strict_types=1);

namespace App;

use Nelmio\Alice\IsAServiceTrait;
use Symfony\Component\DependencyInjection\Attribute\When;

#[When(env: 'staging')]
class OnlyAvailableOnStaging
{
    use IsAServiceTrait;
}

Nelmio/Alice doesn't need to be in composer.json (even if in my real project, it is). What matters here is to have a conditional service using a class only available when doing composer install and not composer install --no-dev.

Another important thing to note: if I comment use IsAServiceTrait and I want to inject an inexistant service, everything works fine

<?php

declare(strict_types=1);

namespace App;

use Fidry\AliceDataFixtures\LoaderInterface;
use Nelmio\Alice\IsAServiceTrait;
use Symfony\Component\DependencyInjection\Attribute\When;

#[When(env: 'staging')]
class OnlyAvailableOnStaging
{
//    use IsAServiceTrait;

    public function __construct(LoaderInterface $loader)
    {
    }
}

Possible Solution

No response

Additional Context

IsAServiceTrait comes from https://github.com/nelmio/alice/blob/a020c0767e10dbb7bf1c193e16e94710691133d9/src/IsAServiceTrait.php

[nicolas-grekas]

You might want to see if ClassExistenceResource::throwOnRequiredClass is called when this happens, and if it's called, debug what happens in it.

[jon-ht]

Hi,

As you pointed it out, my exception is handled by ClassExistenceResource::throwOnRequiredClass.

Howerver, condition trait_exists($class, false) is false because the package is not installed.

symfony/src/Symfony/Component/Config/Resource/ClassExistenceResource.php

Lines 149 to 155 in 42d9d7c

	if (class_exists($class, false) || interface_exists($class, false) || trait_exists($class, false)) {
	if (null !== $previous) {
	throw $previous;
	}
	return;
	}

The only other case where it can skip the error is based on

symfony/src/Symfony/Component/Config/Resource/ClassExistenceResource.php

Lines 193 to 209 in 42d9d7c

	switch ($callerFrame['function']) {
	case 'get_class_methods':
	case 'get_class_vars':
	case 'get_parent_class':
	case 'is_a':
	case 'is_subclass_of':
	case 'class_exists':
	case 'class_implements':
	case 'class_parents':
	case 'trait_exists':
	case 'defined':
	case 'interface_exists':
	case 'method_exists':
	case 'property_exists':
	case 'is_callable':
	return;
	}

But this occurs during an include, so no return either.

In the end, error is thrown as a ReflectionException and caught by Symfony\Component\ErrorHandler\ErrorHandler::handleFatalError. I can't find why this ReflectionException is converted to FatalError

[jon-ht]

I guess this is a side effect or missing case of php/php-src#4697

I tried to add a dummy service with inexistant trait on PHP 7.3.33, no errors. If I switch to PHP 7.3.7, as mentioned here #32395, I got an exception

During class fetch: Uncaught ReflectionException: Class "App\FooTrait" not found while loading "App\DummyService". in /application/api/vendor/symfony/config/Resource/ClassExistenceResource.php

Switching to a version 7.3.6 doesn't throw an exception

There is also this issue #32995 for PHP 7.4 but was resolved in php-src

[carsonbot]

Hey, thanks for your report!
There has not been a lot of activity here for a while. Is this bug still relevant? Have you managed to find a workaround?

[carsonbot]

Hello? This issue is about to be closed if nobody replies.

[carsonbot]

Hey,

I didn't hear anything so I'm going to close it. Feel free to comment if this is still relevant, I can always reopen!