Psr18ClientDiscovery with the Symfony Http Client throws a LogicException

[matt-allan]

PHP version: 7.4.5

Description

With symfony/http-client and nyholm/psr7 installed, calling Psr18ClientDiscovery::find() results in the following LogicException being thrown:

PHP Fatal error:  Uncaught LogicException: You cannot use "Symfony\Component\HttpClient\HttplugClient" as the "php-http/httplug" package is not installed. Try running "composer require php-http/httplug". in /Users/matt/code/discovery-repro/vendor/symfony/http-client/HttplugClient.php:44
Stack trace:
#0 /Users/matt/code/discovery-repro/vendor/composer/ClassLoader.php(444): include()
#1 /Users/matt/code/discovery-repro/vendor/composer/ClassLoader.php(322): Composer\Autoload\includeFile('/Users/matt/cod...')
#2 [internal function]: Composer\Autoload\ClassLoader->loadClass('Symfony\\Compone...')
#3 [internal function]: spl_autoload_call('Symfony\\Compone...')
#4 /Users/matt/code/discovery-repro/vendor/php-http/discovery/src/Strategy/CommonClassesStrategy.php(115): is_subclass_of('Symfony\\Compone...', 'Psr\\Http\\Client...')
#5 [internal function]: Http\Discovery\Strategy\CommonClassesStrategy::getCandidates('Psr\\Http\\Client...')
#6 /Users/matt/code/discovery-repro/vendor/php-http/discovery/src/ClassDiscovery.php(56): call_user_ in /Users/matt/code/discovery-repro/vendor/symfony/http-client/HttplugClient.php on line 44

How to reproduce

composer.json:

{
    "require": {
        "php-http/discovery": "^1.7",
        "psr/http-message": "^1.0",
        "psr/http-factory": "^1.0",
        "psr/http-client": "^1.0",
        "nyholm/psr7": "^1.2",
        "symfony/http-client": "^5.0"
    }
}

index.php:

<?php

use Http\Discovery\Psr18ClientDiscovery;

require __DIR__.'/vendor/autoload.php';

$client = Psr18ClientDiscovery::find();

var_dump($client);

composer install
php ./index.php

Possible Solution

See #170

Additional context

The error seems to indicate Discovery is trying to load Symfony\Component\HttpClient\HttplugClient instead of Symfony\Component\HttpClient\Psr18Client.

I pushed an example here.