[DI] add syntax to stack decorators

src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Compiler/UnusedTagsPass.php

@@ -38,6 +38,7 @@ class UnusedTagsPass implements CompilerPassInterface
         'container.service_locator',
         'container.service_locator_context',
         'container.service_subscriber',
+        'container.stack',
         'controller.argument_value_resolver',
         'controller.service_arguments',
         'data_collector',

src/Symfony/Component/DependencyInjection/Compiler/PassConfig.php

@@ -51,6 +51,7 @@ class PassConfig
         $this->optimizationPasses = [[
             new AutoAliasServicePass(),
             new ValidateEnvPlaceholdersPass(),
+            new ResolveDecoratorStackPass(),
             new ResolveChildDefinitionsPass(),
             new RegisterServiceSubscribersPass(),
             new ResolveParameterPlaceHoldersPass(false, false),

src/Symfony/Component/DependencyInjection/Compiler/ResolveDecoratorStackPass.php

@@ -0,0 +1,127 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\DependencyInjection\Compiler;
+
+use Symfony\Component\DependencyInjection\Alias;
+use Symfony\Component\DependencyInjection\ChildDefinition;
+use Symfony\Component\DependencyInjection\ContainerBuilder;
+use Symfony\Component\DependencyInjection\Definition;
+use Symfony\Component\DependencyInjection\Exception\InvalidArgumentException;
+use Symfony\Component\DependencyInjection\Exception\ServiceCircularReferenceException;
+use Symfony\Component\DependencyInjection\Reference;
+
+/**
+ * @author Nicolas Grekas <p@tchwork.com>
+ */
+class ResolveDecoratorStackPass implements CompilerPassInterface
+{
+    private $tag;
+
+    public function __construct(string $tag = 'container.stack')
+    {
+        $this->tag = $tag;
+    }
+
+    public function process(ContainerBuilder $container)
+    {
+        $stacks = [];
+
+        foreach ($container->findTaggedServiceIds($this->tag) as $id => $tags) {
+            $definition = $container->getDefinition($id);
+
+            if (!$definition instanceof ChildDefinition) {
+                throw new InvalidArgumentException(sprintf('Invalid service "%s": only definitions with a "parent" can have the "%s" tag.', $id, $this->tag));
+            }
+
+            if (!$stack = $definition->getArguments()) {
+                throw new InvalidArgumentException(sprintf('Invalid service "%s": the stack of decorators is empty.', $id));
+            }
+
+            $stacks[$id] = $stack;
+        }
+
+        if (!$stacks) {
+            return;
+        }
+
+        $resolvedDefinitions = [];
+
+        foreach ($container->getDefinitions() as $id => $definition) {
+            if (!isset($stacks[$id])) {
+                $resolvedDefinitions[$id] = $definition;
+                continue;
+            }
+
+            foreach (array_reverse($this->resolveStack($stacks, [$id]), true) as $k => $v) {
+                $resolvedDefinitions[$k] = $v;
+            }
+
+            $alias = $container->setAlias($id, $k);
+
+            if ($definition->getChanges()['public'] ?? false) {
+                $alias->setPublic($definition->isPublic());
+            }
+
+            if ($definition->isDeprecated()) {
+                $alias->setDeprecated(...array_values($definition->getDeprecation('%alias_id%')));
+            }
+        }
+
+        $container->setDefinitions($resolvedDefinitions);
+    }
+
+    private function resolveStack(array $stacks, array $path): array
+    {
+        $definitions = [];
+        $id = end($path);
+        $prefix = '.'.$id.'.';
+
+        if (!isset($stacks[$id])) {
+            return [$id => new ChildDefinition($id)];
+        }
+
+        if (key($path) !== $searchKey = array_search($id, $path)) {
+            throw new ServiceCircularReferenceException($id, \array_slice($path, $searchKey));
+        }
+
+        foreach ($stacks[$id] as $k => $definition) {
+            if ($definition instanceof ChildDefinition && isset($stacks[$definition->getParent()])) {
+                $path[] = $definition->getParent();
+                $definition = unserialize(serialize($definition)); // deep clone
+            } elseif ($definition instanceof Definition) {
+                $definitions[$decoratedId = $prefix.$k] = $definition;
+                continue;
+            } elseif ($definition instanceof Reference || $definition instanceof Alias) {
+                $path[] = (string) $definition;
+            } else {
+                throw new InvalidArgumentException(sprintf('Invalid service "%s": unexpected value of type "%s" found in the stack of decorators.', $id, get_debug_type($definition)));
+            }
+
+            $p = $prefix.$k;
+
+            foreach ($this->resolveStack($stacks, $path) as $k => $v) {
+                $definitions[$decoratedId = $p.$k] = $definition instanceof ChildDefinition ? $definition->setParent($k) : new ChildDefinition($k);
+                $definition = null;
+            }
+            array_pop($path);
+        }
+
+        if (1 === \count($path)) {
+            foreach ($definitions as $k => $definition) {
+                $definition->setPublic(false)->setTags([])->setDecoratedService($decoratedId);
+            }
+            $definition->setDecoratedService(null);
+        }
+
+        return $definitions;
+    }
+}

src/Symfony/Component/DependencyInjection/Loader/Configurator/AbstractServiceConfigurator.php

@@ -81,6 +81,18 @@ abstract class AbstractServiceConfigurator extends AbstractConfigurator
         return $this->parent->get($id);
     }
 
+    /**
+     * Registers a stack of decorator services.
+     *
+     * @param InlineServiceConfigurator[]|ReferenceConfigurator[] $services
+     */
+    final public function stack(string $id, array $services): AliasConfigurator
+    {
+        $this->__destruct();
+
+        return $this->parent->stack($id, $services);
+    }
+
     /**
      * Registers a service.
      */

src/Symfony/Component/DependencyInjection/Loader/Configurator/ServicesConfigurator.php

@@ -15,6 +15,7 @@ use Symfony\Component\DependencyInjection\Alias;
 use Symfony\Component\DependencyInjection\ChildDefinition;
 use Symfony\Component\DependencyInjection\ContainerBuilder;
 use Symfony\Component\DependencyInjection\Definition;
+use Symfony\Component\DependencyInjection\Exception\InvalidArgumentException;
 use Symfony\Component\DependencyInjection\Exception\ServiceNotFoundException;
 use Symfony\Component\DependencyInjection\Loader\PhpFileLoader;
 
@@ -131,6 +132,39 @@ class ServicesConfigurator extends AbstractConfigurator
         return new ServiceConfigurator($this->container, $definition->getInstanceofConditionals(), true, $this, $definition, $id, []);
     }
 
+    /**
+     * Registers a stack of decorator services.
+     *
+     * @param InlineServiceConfigurator[]|ReferenceConfigurator[] $services
+     */
+    final public function stack(string $id, array $services): AliasConfigurator
+    {
+        foreach ($services as $i => $service) {
+            if ($service instanceof InlineServiceConfigurator) {
+                $definition = $service->definition->setInstanceofConditionals($this->instanceof);
+
+                $changes = $definition->getChanges();
+                $definition->setAutowired((isset($changes['autowired']) ? $definition : $this->defaults)->isAutowired());
+                $definition->setAutoconfigured((isset($changes['autoconfigured']) ? $definition : $this->defaults)->isAutoconfigured());
+                $definition->setBindings(array_merge($this->defaults->getBindings(), $definition->getBindings()));
+                $definition->setChanges($changes);
+
+                $services[$i] = $definition;
+            } elseif (!$service instanceof ReferenceConfigurator) {
+                throw new InvalidArgumentException(sprintf('"%s()" expects a list of definitions as returned by "%s()" or "%s()", "%s" given at index "%s" for service "%s".', __METHOD__, InlineServiceConfigurator::FACTORY, ReferenceConfigurator::FACTORY, $service instanceof AbstractConfigurator ? $service::FACTORY.'()' : get_debug_type($service)), $i, $id);
+            }
+        }
+
+        $alias = $this->alias($id, '');
+        $alias->definition = $this->set($id)
+            ->parent('')
+            ->args($services)
+            ->tag('container.stack')
+            ->definition;
+
+        return $alias;
+    }
+
     /**
      * Registers a service.
      */

src/Symfony/Component/DependencyInjection/Loader/XmlFileLoader.php

@@ -112,12 +112,12 @@ class XmlFileLoader extends FileLoader
         }
     }
 
-    private function parseDefinitions(\DOMDocument $xml, string $file, array $defaults)
+    private function parseDefinitions(\DOMDocument $xml, string $file, Definition $defaults)
     {
         $xpath = new \DOMXPath($xml);
         $xpath->registerNamespace('container', self::NS);
 
-        if (false === $services = $xpath->query('//container:services/container:service|//container:services/container:prototype')) {
+        if (false === $services = $xpath->query('//container:services/container:service|//container:services/container:prototype|//container:services/container:stack')) {
             return;
         }
         $this->setCurrentDir(\dirname($file));
@@ -126,12 +126,34 @@ class XmlFileLoader extends FileLoader
         $this->isLoadingInstanceof = true;
         $instanceof = $xpath->query('//container:services/container:instanceof');
         foreach ($instanceof as $service) {
-            $this->setDefinition((string) $service->getAttribute('id'), $this->parseDefinition($service, $file, []));
+            $this->setDefinition((string) $service->getAttribute('id'), $this->parseDefinition($service, $file, new Definition()));
         }
 
         $this->isLoadingInstanceof = false;
         foreach ($services as $service) {
-            if (null !== $definition = $this->parseDefinition($service, $file, $defaults)) {
+            if ('stack' === $service->tagName) {
+                $service->setAttribute('parent', '-');
+                $definition = $this->parseDefinition($service, $file, $defaults)
+                    ->setTags(array_merge_recursive(['container.stack' => [[]]], $defaults->getTags()))
+                ;
+                $this->setDefinition($id = (string) $service->getAttribute('id'), $definition);
+                $stack = [];
+
+                foreach ($this->getChildren($service, 'service') as $k => $frame) {
+                    $k = $frame->getAttribute('id') ?: $k;
+                    $frame->setAttribute('id', $id.'" at index "'.$k);
+
+                    if ($alias = $frame->getAttribute('alias')) {
+                        $this->validateAlias($frame, $file);
+                        $stack[$k] = new Reference($alias);
+                    } else {
+                        $stack[$k] = $this->parseDefinition($frame, $file, $defaults)
+                            ->setInstanceofConditionals($this->instanceof);
+                    }
+                }
+
+                $definition->setArguments($stack);
+            } elseif (null !== $definition = $this->parseDefinition($service, $file, $defaults)) {
                 if ('prototype' === $service->tagName) {
                     $excludes = array_column($this->getChildren($service, 'exclude'), 'nodeValue');
                     if ($service->hasAttribute('exclude')) {
@@ -148,51 +170,24 @@ class XmlFileLoader extends FileLoader
         }
     }
 
-    /**
-     * Get service defaults.
-     */
-    private function getServiceDefaults(\DOMDocument $xml, string $file): array
+    private function getServiceDefaults(\DOMDocument $xml, string $file): Definition
     {
         $xpath = new \DOMXPath($xml);
         $xpath->registerNamespace('container', self::NS);
 
         if (null === $defaultsNode = $xpath->query('//container:services/container:defaults')->item(0)) {
-            return [];
+            return new Definition();
         }
 
-        $bindings = [];
-        foreach ($this->getArgumentsAsPhp($defaultsNode, 'bind', $file) as $argument => $value) {
-            $bindings[$argument] = new BoundArgument($value, true, BoundArgument::DEFAULTS_BINDING, $file);
-        }
+        $defaultsNode->setAttribute('id', '<defaults>');
 
-        $defaults = [
-            'tags' => $this->getChildren($defaultsNode, 'tag'),
-            'bind' => $bindings,
-        ];
-
-        foreach ($defaults['tags'] as $tag) {
-            if ('' === $tag->getAttribute('name')) {
-                throw new InvalidArgumentException(sprintf('The tag name for tag "<defaults>" in "%s" must be a non-empty string.', $file));
-            }
-        }
-
-        if ($defaultsNode->hasAttribute('autowire')) {
-            $defaults['autowire'] = XmlUtils::phpize($defaultsNode->getAttribute('autowire'));
-        }
-        if ($defaultsNode->hasAttribute('public')) {
-            $defaults['public'] = XmlUtils::phpize($defaultsNode->getAttribute('public'));
-        }
-        if ($defaultsNode->hasAttribute('autoconfigure')) {
-            $defaults['autoconfigure'] = XmlUtils::phpize($defaultsNode->getAttribute('autoconfigure'));
-        }
-
-        return $defaults;
+        return $this->parseDefinition($defaultsNode, $file, new Definition());
     }
 
     /**
      * Parses an individual Definition.
      */
-    private function parseDefinition(\DOMElement $service, string $file, array $defaults): ?Definition
+    private function parseDefinition(\DOMElement $service, string $file, Definition $defaults): ?Definition
     {
         if ($alias = $service->getAttribute('alias')) {
             $this->validateAlias($service, $file);
@@ -200,8 +195,8 @@ class XmlFileLoader extends FileLoader
             $this->container->setAlias((string) $service->getAttribute('id'), $alias = new Alias($alias));
             if ($publicAttr = $service->getAttribute('public')) {
                 $alias->setPublic(XmlUtils::phpize($publicAttr));
-            } elseif (isset($defaults['public'])) {
-                $alias->setPublic($defaults['public']);
+            } elseif ($defaults->getChanges()['public'] ?? false) {
+                $alias->setPublic($defaults->isPublic());
             }
 
             if ($deprecated = $this->getChildren($service, 'deprecated')) {
@@ -231,16 +226,11 @@ class XmlFileLoader extends FileLoader
             $definition = new Definition();
         }
 
-        if (isset($defaults['public'])) {
-            $definition->setPublic($defaults['public']);
+        if ($defaults->getChanges()['public'] ?? false) {
+            $definition->setPublic($defaults->isPublic());
         }
-        if (isset($defaults['autowire'])) {
-            $definition->setAutowired($defaults['autowire']);
-        }
-        if (isset($defaults['autoconfigure'])) {
-            $definition->setAutoconfigured($defaults['autoconfigure']);
-        }
-
+        $definition->setAutowired($defaults->isAutowired());
+        $definition->setAutoconfigured($defaults->isAutoconfigured());
         $definition->setChanges([]);
 
         foreach (['class', 'public', 'shared', 'synthetic', 'abstract'] as $key) {
@@ -324,10 +314,6 @@ class XmlFileLoader extends FileLoader
 
         $tags = $this->getChildren($service, 'tag');
 
-        if (!empty($defaults['tags'])) {
-            $tags = array_merge($tags, $defaults['tags']);
-        }
-
         foreach ($tags as $tag) {
             $parameters = [];
             foreach ($tag->attributes as $name => $node) {
@@ -349,16 +335,17 @@ class XmlFileLoader extends FileLoader
             $definition->addTag($tag->getAttribute('name'), $parameters);
         }
 
+        $definition->setTags(array_merge_recursive($definition->getTags(), $defaults->getTags()));
+
         $bindings = $this->getArgumentsAsPhp($service, 'bind', $file);
         $bindingType = $this->isLoadingInstanceof ? BoundArgument::INSTANCEOF_BINDING : BoundArgument::SERVICE_BINDING;
         foreach ($bindings as $argument => $value) {
             $bindings[$argument] = new BoundArgument($value, true, $bindingType, $file);
         }
 
-        if (isset($defaults['bind'])) {
-            // deep clone, to avoid multiple process of the same instance in the passes
-            $bindings = array_merge(unserialize(serialize($defaults['bind'])), $bindings);
-        }
+        // deep clone, to avoid multiple process of the same instance in the passes
+        $bindings = array_merge(unserialize(serialize($defaults->getBindings())), $bindings);
+
         if ($bindings) {
             $definition->setBindings($bindings);
         }
@@ -443,7 +430,7 @@ class XmlFileLoader extends FileLoader
         // resolve definitions
         uksort($definitions, 'strnatcmp');
         foreach (array_reverse($definitions) as $id => list($domElement, $file)) {
-            if (null !== $definition = $this->parseDefinition($domElement, $file, [])) {
+            if (null !== $definition = $this->parseDefinition($domElement, $file, new Definition())) {
                 $this->setDefinition($id, $definition);
             }
         }

src/Symfony/Component/DependencyInjection/Loader/YamlFileLoader.php

@@ -315,19 +315,20 @@ class YamlFileLoader extends FileLoader
      *
      * @throws InvalidArgumentException When tags are invalid
      */
-    private function parseDefinition(string $id, $service, string $file, array $defaults)
+    private function parseDefinition(string $id, $service, string $file, array $defaults, bool $return = false)
     {
         if (preg_match('/^_[a-zA-Z0-9_]*$/', $id)) {
             throw new InvalidArgumentException(sprintf('Service names that start with an underscore are reserved. Rename the "%s" service or define it in XML instead.', $id));
         }
 
         if (\is_string($service) && 0 === strpos($service, '@')) {
-            $this->container->setAlias($id, $alias = new Alias(substr($service, 1)));
+            $alias = new Alias(substr($service, 1));
+
             if (isset($defaults['public'])) {
                 $alias->setPublic($defaults['public']);
             }
 
-            return;
+            return $return ? $alias : $this->container->setAlias($id, $alias);
         }
 
         if (\is_array($service) && $this->isUsingShortSyntax($service)) {
@@ -342,10 +343,52 @@ class YamlFileLoader extends FileLoader
             throw new InvalidArgumentException(sprintf('A service definition must be an array or a string starting with "@" but "%s" found for service "%s" in "%s". Check your YAML syntax.', get_debug_type($service), $id, $file));
         }
 
+        if (isset($service['stack'])) {
+            if (!\is_array($service['stack'])) {
+                throw new InvalidArgumentException(sprintf('A stack must be an array of definitions, "%s" given for service "%s" in "%s". Check your YAML syntax.', get_debug_type($service), $id, $file));
+            }
+
+            $stack = [];
+
+            foreach ($service['stack'] as $k => $frame) {
+                if (\is_array($frame) && 1 === \count($frame) && !isset(self::$serviceKeywords[key($frame)])) {
+                    $frame = [
+                        'class' => key($frame),
+                        'arguments' => current($frame),
+                    ];
+                }
+
+                if (\is_array($frame) && isset($frame['stack'])) {
+                    throw new InvalidArgumentException(sprintf('Service stack "%s" cannot contain another stack in "%s".', $id, $file));
+                }
+
+                $definition = $this->parseDefinition($id.'" at index "'.$k, $frame, $file, $defaults, true);
+
+                if ($definition instanceof Definition) {
+                    $definition->setInstanceofConditionals($this->instanceof);
+                }
+
+                $stack[$k] = $definition;
+            }
+
+            if ($diff = array_diff(array_keys($service), ['stack', 'public', 'deprecated'])) {
+                throw new InvalidArgumentException(sprintf('Invalid attribute "%s"; supported ones are "public" and "deprecated" for service "%s" in "%s". Check your YAML syntax.', implode('", "', $diff), $id, $file));
+            }
+
+            $service = [
+                'parent' => '',
+                'arguments' => $stack,
+                'tags' => ['container.stack'],
+                'public' => $service['public'] ?? null,
+                'deprecated' => $service['deprecated'] ?? null,
+            ];
+        }
+
         $this->checkDefinition($id, $service, $file);
 
         if (isset($service['alias'])) {
-            $this->container->setAlias($id, $alias = new Alias($service['alias']));
+            $alias = new Alias($service['alias']);
+
             if (isset($service['public'])) {
                 $alias->setPublic($service['public']);
             } elseif (isset($defaults['public'])) {
@@ -372,7 +415,7 @@ class YamlFileLoader extends FileLoader
                 }
             }
 
-            return;
+            return $return ? $alias : $this->container->setAlias($id, $alias);
         }
 
         if ($this->isLoadingInstanceof) {
@@ -426,7 +469,7 @@ class YamlFileLoader extends FileLoader
             $definition->setAbstract($service['abstract']);
         }
 
-        if (\array_key_exists('deprecated', $service)) {
+        if (isset($service['deprecated'])) {
             $deprecation = \is_array($service['deprecated']) ? $service['deprecated'] : ['message' => $service['deprecated']];
 
             if (!isset($deprecation['package'])) {
@@ -601,6 +644,14 @@ class YamlFileLoader extends FileLoader
             throw new InvalidArgumentException(sprintf('A "resource" attribute must be set when the "namespace" attribute is set for service "%s" in "%s". Check your YAML syntax.', $id, $file));
         }
 
+        if ($return) {
+            if (\array_key_exists('resource', $service)) {
+                throw new InvalidArgumentException(sprintf('Invalid "resource" attribute found for service "%s" in "%s". Check your YAML syntax.', $id, $file));
+            }
+
+            return $definition;
+        }
+
         if (\array_key_exists('resource', $service)) {
             if (!\is_string($service['resource'])) {
                 throw new InvalidArgumentException(sprintf('A "resource" attribute must be of type string for service "%s" in "%s". Check your YAML syntax.', $id, $file));

src/Symfony/Component/DependencyInjection/Loader/schema/dic/services/services-1.0.xsd

@@ -57,6 +57,7 @@
       <xsd:element name="prototype" type="prototype" minOccurs="0" />
       <xsd:element name="defaults" type="defaults" minOccurs="0" maxOccurs="1" />
       <xsd:element name="instanceof" type="instanceof" minOccurs="0" />
+      <xsd:element name="stack" type="stack" minOccurs="0" />
     </xsd:choice>
   </xsd:complexType>
 
@@ -176,6 +177,15 @@
     <xsd:attribute name="autoconfigure" type="boolean" />
   </xsd:complexType>
 
+  <xsd:complexType name="stack">
+    <xsd:choice maxOccurs="unbounded">
+      <xsd:element name="service" type="service" minOccurs="1" />
+      <xsd:element name="deprecated" type="deprecated" minOccurs="0" maxOccurs="1" />
+    </xsd:choice>
+    <xsd:attribute name="id" type="xsd:string" use="required" />
+    <xsd:attribute name="public" type="boolean" />
+  </xsd:complexType>
+
   <xsd:complexType name="tag">
     <xsd:attribute name="name" type="xsd:string" use="required" />
     <xsd:anyAttribute namespace="##any" processContents="lax" />

src/Symfony/Component/DependencyInjection/Tests/Fixtures/config/stack.php

@@ -0,0 +1,50 @@
+<?php
+
+namespace Symfony\Component\DependencyInjection\Loader\Configurator;
+
+use Symfony\Component\DependencyInjection\Tests\Fixtures\Prototype\Foo;
+
+return function (ContainerConfigurator $c) {
+    $services = $c->services();
+
+    $services->stack('stack_a', [
+        service('stdClass')
+            ->property('label', 'A')
+            ->property('inner', ref('.inner')),
+        service('stdClass')
+            ->property('label', 'B')
+            ->property('inner', ref('.inner')),
+        service('stdClass')
+            ->property('label', 'C'),
+    ])->public();
+
+    $services->stack('stack_abstract', [
+        service('stdClass')
+            ->property('label', 'A')
+            ->property('inner', ref('.inner')),
+        service('stdClass')
+            ->property('label', 'B')
+            ->property('inner', ref('.inner')),
+    ]);
+
+    $services->stack('stack_b', [
+        ref('stack_abstract'),
+        service('stdClass')
+            ->property('label', 'C'),
+    ])->public();
+
+    $services->stack('stack_c', [
+        service('stdClass')
+            ->property('label', 'Z')
+            ->property('inner', ref('.inner')),
+        ref('stack_a'),
+    ])->public();
+
+    $services->stack('stack_d', [
+        service()
+            ->parent('stack_abstract')
+            ->property('label', 'Z'),
+        service('stdClass')
+            ->property('label', 'C'),
+    ])->public();
+};

src/Symfony/Component/DependencyInjection/Tests/Fixtures/xml/stack.xml

@@ -0,0 +1,53 @@
+<?xml version="1.0" encoding="utf-8"?>
+<container xmlns="http://symfony.com/schema/dic/services" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://symfony.com/schema/dic/services https://symfony.com/schema/dic/services/services-1.0.xsd">
+    <services>
+        <stack id="stack_a" public="true">
+            <service class="stdClass">
+                <property name="label">A</property>
+                <property name="inner" type="service" id=".inner" />
+            </service>
+            <service class="stdClass">
+                <property name="label">B</property>
+                <property name="inner" type="service" id=".inner" />
+            </service>
+            <service class="stdClass">
+                <property name="label">C</property>
+            </service>
+        </stack>
+
+        <stack id="stack_abstract">
+            <service class="stdClass" abstract="true">
+                <property name="label">A</property>
+                <property name="inner" type="service" id=".inner" />
+            </service>
+            <service class="stdClass">
+                <property name="label">B</property>
+                <property name="inner" type="service" id=".inner" />
+            </service>
+        </stack>
+
+        <stack id="stack_b" public="true">
+            <service alias="stack_abstract" />
+            <service class="stdClass">
+                <property name="label">C</property>
+            </service>
+        </stack>
+
+        <stack id="stack_c" public="true">
+            <service class="stdClass">
+                <property name="label">Z</property>
+                <property name="inner" type="service" id=".inner" />
+            </service>
+            <service alias="stack_a" />
+        </stack>
+
+        <stack id="stack_d" public="true">
+            <service parent="stack_abstract">
+                <property name="label">Z</property>
+            </service>
+            <service class="stdClass">
+                <property name="label">C</property>
+            </service>
+        </stack>
+    </services>
+</container>

src/Symfony/Component/DependencyInjection/Tests/Fixtures/yaml/stack.yaml

@@ -0,0 +1,67 @@
+services:
+    stack_short:
+        stack:
+            - stdClass: [1, 2]
+
+    stack_a:
+        public: true
+        stack:
+            - class: stdClass
+              properties:
+                  label: A
+                  inner: '@.inner'
+            - class: stdClass
+              properties:
+                  label: B
+                  inner: '@.inner'
+            - class: stdClass
+              properties:
+                  label: C
+
+    stack_abstract:
+        stack:
+            - class: stdClass
+              abstract: true
+              properties:
+                  label: A
+                  inner: '@.inner'
+            - class: stdClass
+              properties:
+                  label: B
+                  inner: '@.inner'
+
+    stack_b:
+        public: true
+        stack:
+            - alias: 'stack_abstract'
+            - class: stdClass
+              properties:
+                  label: C
+
+    stack_c:
+        public: true
+        stack:
+            - class: stdClass
+              properties:
+                  label: Z
+                  inner: '@.inner'
+            - '@stack_a'
+
+    stack_d:
+        public: true
+        stack:
+            - parent: 'stack_abstract'
+              properties:
+                  label: 'Z'
+            - class: stdClass
+              properties:
+                  label: C
+
+    stack_e:
+        public: true
+        stack:
+            - class: stdClass
+              properties:
+                  label: Y
+                  inner: '@.inner'
+            - '@stack_d'

src/Symfony/Component/DependencyInjection/Tests/Loader/PhpFileLoaderTest.php

@@ -101,6 +101,38 @@ class PhpFileLoaderTest extends TestCase
         $container->compile();
     }
 
+    public function testStack()
+    {
+        $container = new ContainerBuilder();
+
+        $loader = new PhpFileLoader($container, new FileLocator(realpath(__DIR__.'/../Fixtures').'/config'));
+        $loader->load('stack.php');
+
+        $container->compile();
+
+        $expected = (object) [
+            'label' => 'A',
+            'inner' => (object) [
+                'label' => 'B',
+                'inner' => (object) [
+                    'label' => 'C',
+                ],
+            ],
+        ];
+        $this->assertEquals($expected, $container->get('stack_a'));
+        $this->assertEquals($expected, $container->get('stack_b'));
+
+        $expected = (object) [
+            'label' => 'Z',
+            'inner' => $expected,
+        ];
+        $this->assertEquals($expected, $container->get('stack_c'));
+
+        $expected = $expected->inner;
+        $expected->label = 'Z';
+        $this->assertEquals($expected, $container->get('stack_d'));
+    }
+
     /**
      * @group legacy
      * @expectedDeprecation Since symfony/dependency-injection 5.1: The signature of method "Symfony\Component\DependencyInjection\Loader\Configurator\Traits\DeprecateTrait::deprecate()" requires 3 arguments: "string $package, string $version, string $message", not defining them is deprecated.

src/Symfony/Component/DependencyInjection/Tests/Loader/XmlFileLoaderTest.php

@@ -1039,4 +1039,36 @@ class XmlFileLoaderTest extends TestCase
         $arguments = $container->getDefinition(FooWithAbstractArgument::class)->getArguments();
         $this->assertInstanceOf(AbstractArgument::class, $arguments['$baz']);
     }
+
+    public function testStack()
+    {
+        $container = new ContainerBuilder();
+
+        $loader = new XmlFileLoader($container, new FileLocator(self::$fixturesPath.'/xml'));
+        $loader->load('stack.xml');
+
+        $container->compile();
+
+        $expected = (object) [
+            'label' => 'A',
+            'inner' => (object) [
+                'label' => 'B',
+                'inner' => (object) [
+                    'label' => 'C',
+                ],
+            ],
+        ];
+        $this->assertEquals($expected, $container->get('stack_a'));
+        $this->assertEquals($expected, $container->get('stack_b'));
+
+        $expected = (object) [
+            'label' => 'Z',
+            'inner' => $expected,
+        ];
+        $this->assertEquals($expected, $container->get('stack_c'));
+
+        $expected = $expected->inner;
+        $expected->label = 'Z';
+        $this->assertEquals($expected, $container->get('stack_d'));
+    }
 }

src/Symfony/Component/DependencyInjection/Tests/Loader/YamlFileLoaderTest.php

@@ -958,4 +958,44 @@ class YamlFileLoaderTest extends TestCase
 
         $this->assertSame($expected, $container->getDefinition('foo')->getMethodCalls());
     }
+
+    public function testStack()
+    {
+        $container = new ContainerBuilder();
+
+        $loader = new YamlFileLoader($container, new FileLocator(self::$fixturesPath.'/yaml'));
+        $loader->load('stack.yaml');
+
+        $this->assertSame([1, 2], $container->getDefinition('stack_short')->getArguments()[0]->getArguments());
+
+        $container->compile();
+
+        $expected = (object) [
+            'label' => 'A',
+            'inner' => (object) [
+                'label' => 'B',
+                'inner' => (object) [
+                    'label' => 'C',
+                ],
+            ],
+        ];
+        $this->assertEquals($expected, $container->get('stack_a'));
+        $this->assertEquals($expected, $container->get('stack_b'));
+
+        $expected = (object) [
+            'label' => 'Z',
+            'inner' => $expected,
+        ];
+        $this->assertEquals($expected, $container->get('stack_c'));
+
+        $expected = $expected->inner;
+        $expected->label = 'Z';
+        $this->assertEquals($expected, $container->get('stack_d'));
+
+        $expected = (object) [
+            'label' => 'Y',
+            'inner' => $expected,
+        ];
+        $this->assertEquals($expected, $container->get('stack_e'));
+    }
 }