From 95ed512a75ffdbab37173d9ba2c748a3daebf675 Mon Sep 17 00:00:00 2001
From: Jillur Rahman <22579419+developerjillur@users.noreply.github.com>
Date: Wed, 28 Oct 2026 12:09:55 +0600
Subject: [PATCH] Fix alias-aware field selection merging

---
 src/Type/Definition/ResolveInfo.php |  11 ++-
 tests/Type/ResolveInfoTest.php      | 111 ++++++++++++++++++++++++++++
 2 files changed, 118 insertions(+), 4 deletions(-)

diff --git a/src/Type/Definition/ResolveInfo.php b/src/Type/Definition/ResolveInfo.php
index 5204cd547..64d131963 100644
--- a/src/Type/Definition/ResolveInfo.php
+++ b/src/Type/Definition/ResolveInfo.php
@@ -350,7 +350,7 @@ public function getFieldSelectionWithAliases(int $depth = 0): array
                 $field = $this->parentType->getField($fieldNode->name->value);
                 $fieldType = $field->getType();
 
-                $fields = array_merge_recursive(
+                $fields = array_replace_recursive(
                     $fields,
                     $this->foldSelectionWithAlias($selectionSet, $depth, $fieldType)
                 );
@@ -470,7 +470,10 @@ private function foldSelectionWithAlias(SelectionSetNode $selectionSet, int $des
                     continue;
                 }
 
-                $aliasInfo['selectionSet'] = $this->foldSelectionWithAlias($nestedSelectionSet, $descend - 1, $fieldType);
+                $aliasInfo['selectionSet'] = array_replace_recursive(
+                    $aliasInfo['selectionSet'] ?? [],
+                    $this->foldSelectionWithAlias($nestedSelectionSet, $descend - 1, $fieldType)
+                );
             } elseif ($selection instanceof FragmentSpreadNode) {
                 $spreadName = $selection->name->value;
                 $fragment = $this->fragments[$spreadName] ?? null;
@@ -481,7 +484,7 @@ private function foldSelectionWithAlias(SelectionSetNode $selectionSet, int $des
                 $fieldType = $this->schema->getType($fragment->typeCondition->name->value);
                 assert($fieldType instanceof Type, 'ensured by query validation');
 
-                $fields = array_merge_recursive(
+                $fields = array_replace_recursive(
                     $this->foldSelectionWithAlias($fragment->selectionSet, $descend, $fieldType),
                     $fields
                 );
@@ -500,7 +503,7 @@ private function foldSelectionWithAlias(SelectionSetNode $selectionSet, int $des
                     continue;
                 }
 
-                $fields = array_merge_recursive(
+                $fields = array_replace_recursive(
                     $this->foldSelectionWithAlias($selection->selectionSet, $descend, $fieldType),
                     $fields
                 );
diff --git a/tests/Type/ResolveInfoTest.php b/tests/Type/ResolveInfoTest.php
index 4940a2570..e6a6fda4c 100644
--- a/tests/Type/ResolveInfoTest.php
+++ b/tests/Type/ResolveInfoTest.php
@@ -1048,6 +1048,117 @@ public function testGetFieldSelectionWithAliases(): void
         self::assertEmpty($result10->errors, 'Query With Union type should have no errors');
     }
 
+    /** @dataProvider providerGetFieldSelectionWithAliasesMergedSelections */
+    public function testGetFieldSelectionWithAliasesMergedSelections(string $document, bool $recursiveType): void
+    {
+        $post = new ObjectType([
+            'name' => 'Post',
+            'fields' => [
+                'id' => Type::id(),
+                'text' => Type::string(),
+            ],
+        ]);
+
+        if ($recursiveType) {
+            $post->config['fields'] = [
+                'id' => Type::id(),
+                'text' => Type::string(),
+                'related' => $post,
+            ];
+        }
+
+        $user = new ObjectType([
+            'name' => 'User',
+            'fields' => [
+                'name' => Type::string(),
+                'posts' => [
+                    'type' => Type::nonNull(Type::listOf(Type::nonNull($post))),
+                    'args' => [
+                        'limit' => Type::int(),
+                        'ids' => Type::listOf(Type::int()),
+                    ],
+                ],
+            ],
+        ]);
+
+        $selection = null;
+        $query = new ObjectType([
+            'name' => 'Query',
+            'fields' => [
+                'user' => [
+                    'type' => $user,
+                    'resolve' => static function ($value, array $args, $context, ResolveInfo $info) use (&$selection) {
+                        $selection = $info->getFieldSelectionWithAliases(1);
+
+                        return null;
+                    },
+                ],
+            ],
+        ]);
+
+        $result = GraphQL::executeQuery(new Schema(['query' => $query]), $document);
+
+        self::assertSame([], $result->errors);
+        self::assertIsArray($selection);
+        self::assertSame($post, $selection['posts']['recent']['type']);
+        self::assertSame(Type::string(), $selection['name']['name']['type']);
+        self::assertSame(['limit' => 2, 'ids' => [1, 2]], $selection['posts']['recent']['args']);
+        self::assertEquals([
+            'name' => [
+                'name' => ['args' => [], 'type' => Type::string()],
+            ],
+            'posts' => [
+                'recent' => [
+                    'args' => ['limit' => 2, 'ids' => [1, 2]],
+                    'type' => $post,
+                    'selectionSet' => [
+                        'id' => [
+                            'id' => ['args' => [], 'type' => Type::id()],
+                        ],
+                        'text' => [
+                            'text' => ['args' => [], 'type' => Type::string()],
+                        ],
+                    ],
+                ],
+            ],
+        ], $selection);
+    }
+
+    /** @return \Generator<string, array{string, bool}> */
+    public static function providerGetFieldSelectionWithAliasesMergedSelections(): \Generator
+    {
+        $first = 'name recent: posts(limit: 2, ids: [1, 2]) { id }';
+        $second = 'name recent: posts(limit: 2, ids: [1, 2]) { text }';
+
+        $documents = [
+            'named fragment after field' => <<<GRAPHQL
+            { user { {$first} ...Posts } }
+            fragment Posts on User { {$second} }
+            GRAPHQL,
+            'named fragment before field' => <<<GRAPHQL
+            { user { ...Posts {$second} } }
+            fragment Posts on User { {$first} }
+            GRAPHQL,
+            'inline fragment after field' => <<<GRAPHQL
+            { user { {$first} ... on User { {$second} } } }
+            GRAPHQL,
+            'inline fragment before field' => <<<GRAPHQL
+            { user { ... on User { {$first} } {$second} } }
+            GRAPHQL,
+            'duplicate root field nodes' => <<<GRAPHQL
+            { user { {$first} } user { {$second} } }
+            GRAPHQL,
+            'duplicate nested field nodes' => <<<GRAPHQL
+            { user { {$first} {$second} } }
+            GRAPHQL,
+        ];
+
+        foreach ($documents as $name => $document) {
+            yield $name => [$document, false];
+            yield "{$name} with recursive type" => [$document, true];
+        }
+    }
+
     public function testPathAndUnaliasedPath(): void
     {
         $resolveInfo = new ObjectType([