[DeepClone] Idempotent readonly hydrate

nicolas-grekas · nicolas-grekas · commit d20a7c21be1a · 2026-04-15T10:17:48.000+02:00
diff --git a/src/DeepClone/DeepClone.php b/src/DeepClone/DeepClone.php
@@ -1371,7 +1371,17 @@ private static function getSimpleHydrator(string $class, int $flags = 0): \Closu
                             : $propertyReflector->setRawValue(...);
                     }
                 } elseif ($propertyReflector->isReadOnly()) {
-                    $notByRef->{$propertyReflector->name} = $propertyReflector->setValue(...);
+                    $notByRef->{$propertyReflector->name} = static function ($object, $value) use ($propertyReflector) {
+                        /* Idempotent hydrate: if the readonly slot already holds
+                         * the same value (===), silently skip. Avoids "Cannot
+                         * modify readonly property" on no-op rehydration. */
+                        if ($propertyReflector->isInitialized($object)
+                            && $propertyReflector->getValue($object) === $value)
+                        {
+                            return;
+                        }
+                        $propertyReflector->setValue($object, $value);
+                    };
                 }
             }
 
diff --git a/tests/DeepClone/DeepCloneTest.php b/tests/DeepClone/DeepCloneTest.php
@@ -1599,4 +1599,33 @@ public function testHydrateFlagsUnknownBitThrows()
         deepclone_hydrate(\stdClass::class, [], [], 1 << 30);
     }
 
+    public function testHydrateReadonlyIdempotentSkipsSameValue()
+    {
+        $obj = new HydrateReadonly(123);
+        $obj = deepclone_hydrate($obj, [HydrateReadonly::class => ['value' => 123]]);
+        $this->assertSame(123, $obj->getValue());
+    }
+
+    public function testHydrateReadonlyDifferentValueThrows()
+    {
+        $obj = new HydrateReadonly(123);
+        try {
+            deepclone_hydrate($obj, [HydrateReadonly::class => ['value' => 456]]);
+            $this->fail('Expected Error on readonly overwrite');
+        } catch (\Error $e) {
+            $this->assertStringContainsString('readonly', $e->getMessage());
+        }
+        $this->assertSame(123, $obj->getValue());
+    }
+
+    public function testHydrateReadonlyObjectIdentityIsSkipped()
+    {
+        $inner = new \stdClass();
+        $host = new class ($inner) {
+            public function __construct(public readonly \stdClass $o) {}
+        };
+        $class = $host::class;
+        $host = deepclone_hydrate($host, [$class => ['o' => $inner]]);
+        $this->assertSame($inner, $host->o);
+    }
 }

Original file line number	Diff line number	Diff line change
`@@ -1371,7 +1371,17 @@ private static function getSimpleHydrator(string $class, int $flags = 0): \Closu`
`1371`	`1371`	`: $propertyReflector->setRawValue(...);`
`1372`	`1372`	`}`
`1373`	`1373`	`} elseif ($propertyReflector->isReadOnly()) {`
`1374`		`- $notByRef->{$propertyReflector->name} = $propertyReflector->setValue(...);`
	`1374`	`+ $notByRef->{$propertyReflector->name} = static function ($object, $value) use ($propertyReflector) {`
	`1375`	`+ /* Idempotent hydrate: if the readonly slot already holds`
	`1376`	`+ * the same value (===), silently skip. Avoids "Cannot`
	`1377`	`+ * modify readonly property" on no-op rehydration. */`
	`1378`	`+ if ($propertyReflector->isInitialized($object)`
	`1379`	`+ && $propertyReflector->getValue($object) === $value)`
	`1380`	`+ {`
	`1381`	`+ return;`
	`1382`	`+ }`
	`1383`	`+ $propertyReflector->setValue($object, $value);`
	`1384`	`+ };`
`1375`	`1385`	`}`
`1376`	`1386`	`}`
`1377`	`1387`