feature #42959 [DependencyInjection] Make auto-aliases private by default (nicolas-grekas)

This PR was merged into the 5.4 branch.

Discussion
----------

[DependencyInjection] Make auto-aliases private by default

| Q             | A
| ------------- | ---
| Branch?       | 5.4
| Bug fix?      | no
| New feature?  | no
| Deprecations? | yes
| Tickets       | -
| License       | MIT
| Doc PR        | -

Replaces #41209

Before, this creates a public autoalias:
```yaml
    app.lock:
        tags:
            - { name: auto_alias, format: "app.%database_type%_lock" }
```

After, this creates a public autoalias:
```yaml
    app.lock:
        public: true
        tags:
            - { name: auto_alias, format: "app.%database_type%_lock" }
```

Omitting `public: true` will trigger a deprecation warning when the alias is accessed from `$container->get()`. In 6.0, the alias will be private by default if `public: true` is not set.

Commits
-------

679f25eace [DependencyInjection] Make auto-aliases private by default

Author: nicolas-grekas

CHANGELOG.md

@@ -6,6 +6,7 @@ CHANGELOG
 
  * Add `service_closure()` to the PHP-DSL
  * Add support for autoconfigurable attributes on methods, properties and parameters
+ * Make auto-aliases private by default
 
 5.3
 ---

Compiler/AutoAliasServicePass.php

@@ -20,6 +20,8 @@
  */
 class AutoAliasServicePass implements CompilerPassInterface
 {
+    private $privateAliases = [];
+
     /**
      * {@inheritdoc}
      */
@@ -33,9 +35,26 @@ public function process(ContainerBuilder $container)
 
                 $aliasId = $container->getParameterBag()->resolveValue($tag['format']);
                 if ($container->hasDefinition($aliasId) || $container->hasAlias($aliasId)) {
-                    $container->setAlias($serviceId, new Alias($aliasId, true));
+                    $alias = new Alias($aliasId, $container->getDefinition($serviceId)->isPublic());
+                    $container->setAlias($serviceId, $alias);
+
+                    if (!$alias->isPublic()) {
+                        $alias->setPublic(true);
+                        $this->privateAliases[] = $alias;
+                    }
                 }
             }
         }
     }
+
+    /**
+     * @internal to be removed in Symfony 6.0
+     */
+    public function getPrivateAliases(): array
+    {
+        $privateAliases = $this->privateAliases;
+        $this->privateAliases = [];
+
+        return $privateAliases;
+    }
 }

Compiler/PassConfig.php

@@ -51,7 +51,7 @@ public function __construct()
         ];
 
         $this->optimizationPasses = [[
-            new AutoAliasServicePass(),
+            $autoAliasServicePass = new AutoAliasServicePass(),
             new ValidateEnvPlaceholdersPass(),
             new ResolveDecoratorStackPass(),
             new ResolveChildDefinitionsPass(),
@@ -78,7 +78,7 @@ public function __construct()
 
         $this->removingPasses = [[
             new RemovePrivateAliasesPass(),
-            new ReplaceAliasByActualDefinitionPass(),
+            (new ReplaceAliasByActualDefinitionPass())->setAutoAliasServicePass($autoAliasServicePass),
             new RemoveAbstractDefinitionsPass(),
             new RemoveUnusedDefinitionsPass(),
             new AnalyzeServiceReferencesPass(),

Compiler/ReplaceAliasByActualDefinitionPass.php

@@ -25,6 +25,19 @@
 class ReplaceAliasByActualDefinitionPass extends AbstractRecursivePass
 {
     private $replacements;
+    private $autoAliasServicePass;
+
+    /**
+     * @internal to be removed in Symfony 6.0
+     *
+     * @return $this
+     */
+    public function setAutoAliasServicePass(AutoAliasServicePass $autoAliasServicePass): self
+    {
+        $this->autoAliasServicePass = $autoAliasServicePass;
+
+        return $this;
+    }
 
     /**
      * Process the Container to replace aliases with service definitions.
@@ -36,15 +49,25 @@ public function process(ContainerBuilder $container)
         // First collect all alias targets that need to be replaced
         $seenAliasTargets = [];
         $replacements = [];
+
+        $privateAliases = $this->autoAliasServicePass ? $this->autoAliasServicePass->getPrivateAliases() : [];
+        foreach ($privateAliases as $target) {
+            $target->setDeprecated('symfony/dependency-injection', '5.4', 'Accessing the "%alias_id%" service directly from the container is deprecated, use dependency injection instead.');
+        }
+
         foreach ($container->getAliases() as $definitionId => $target) {
             $targetId = (string) $target;
             // Special case: leave this target alone
             if ('service_container' === $targetId) {
                 continue;
             }
-            // Check if target needs to be replaces
+            // Check if target needs to be replaced
             if (isset($replacements[$targetId])) {
                 $container->setAlias($definitionId, $replacements[$targetId])->setPublic($target->isPublic());
+
+                if ($target->isDeprecated()) {
+                    $container->getAlias($definitionId)->setDeprecated(...array_values($target->getDeprecation('%alias_id%')));
+                }
             }
             // No need to process the same target twice
             if (isset($seenAliasTargets[$targetId])) {
@@ -69,6 +92,10 @@ public function process(ContainerBuilder $container)
             $container->setDefinition($definitionId, $definition);
             $container->removeDefinition($targetId);
             $replacements[$targetId] = $definitionId;
+
+            if ($target->isPublic() && $target->isDeprecated()) {
+                $definition->addTag('container.private', $target->getDeprecation('%service_id%'));
+            }
         }
         $this->replacements = $replacements;
 

Tests/Compiler/ReplaceAliasByActualDefinitionPassTest.php

@@ -31,20 +31,22 @@ public function testProcess()
         $bDefinition = new Definition('\stdClass');
         $container->setDefinition('b', $bDefinition);
 
-        $container->setAlias('a_alias', 'a')->setPublic(true);
-        $container->setAlias('b_alias', 'b')->setPublic(true);
+        $container->setAlias('a_alias', 'a')->setPublic(true)->setDeprecated('foo/bar', '1.2', '%alias_id%');
+        $container->setAlias('b_alias', 'b')->setPublic(true)->setDeprecated('foo/bar', '1.2', '%alias_id%');
 
         $container->setAlias('container', 'service_container');
 
         $this->process($container);
 
         $this->assertTrue($container->has('a'), '->process() does nothing to public definitions.');
         $this->assertTrue($container->hasAlias('a_alias'));
+        $this->assertTrue($container->getAlias('a_alias')->isDeprecated());
         $this->assertFalse($container->has('b'), '->process() removes non-public definitions.');
         $this->assertTrue(
             $container->has('b_alias') && !$container->hasAlias('b_alias'),
             '->process() replaces alias to actual.'
         );
+        $this->assertTrue($container->getDefinition('b_alias')->hasTag('container.private'));
 
         $this->assertTrue($container->has('container'));