bug #31551 [ProxyManager] isProxyCandidate() does not take into accou…

…nt interfaces (andrerom)

This PR was merged into the 3.4 branch.

Discussion
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[ProxyManager] isProxyCandidate() does not take into account interfaces

| Q             | A
| ------------- | ---
| Branch?       | 2.8
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets |
| License       | MIT
| Doc PR        | N/A

When using factories it's common best practice to use interface as class name, especially in cases
where you know implementation can differ. Before this fix ProxyManager did not allow these to be lazy.

As we have have this issue on 2.8 and 3.4. it's very hard to debug, and goes against best practice for factories to not fix it, this is suggested for 2.8.

Commits
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e3739b1 [Bridge\ProxyManager] isProxyCandidate() does not take into account interfaces

src/Symfony/Bridge/ProxyManager/LazyProxy/PhpDumper/ProxyDumper.php

@@ -47,7 +47,7 @@ public function __construct($salt = '')
      */
     public function isProxyCandidate(Definition $definition)
     {
-        return $definition->isLazy() && ($class = $definition->getClass()) && class_exists($class);
+        return $definition->isLazy() && ($class = $definition->getClass()) && (class_exists($class) || interface_exists($class));
     }
 
     /**

src/Symfony/Bridge/ProxyManager/Tests/LazyProxy/PhpDumper/ProxyDumperTest.php

@@ -15,6 +15,7 @@
 use Symfony\Bridge\ProxyManager\LazyProxy\PhpDumper\ProxyDumper;
 use Symfony\Component\DependencyInjection\ContainerBuilder;
 use Symfony\Component\DependencyInjection\Definition;
+use Symfony\Component\DependencyInjection\LazyProxy\PhpDumper\DumperInterface;
 
 /**
  * Tests for {@see \Symfony\Bridge\ProxyManager\LazyProxy\PhpDumper\ProxyDumper}.
@@ -137,6 +138,7 @@ public function getProxyCandidates()
         $definitions = [
             [new Definition(__CLASS__), true],
             [new Definition('stdClass'), true],
+            [new Definition(DumperInterface::class), true],
             [new Definition(uniqid('foo', true)), false],
             [new Definition(), false],
         ];