From d2ffaf574db94b0d8ad8dabf3a45ad1d6f736b0e Mon Sep 17 00:00:00 2001
From: Chris Riley <chris.riley@bexio.com>
Date: Tue, 14 Dec 2021 16:48:33 +0000
Subject: [PATCH] \#126: Fixes issues reading/writing typed properties which
 are uninitialised and not passed in the data array

---
 .../Visitor/HydratorMethodsVisitor.php        | 20 ++++++++++++++--
 .../Functional/HydratorFunctionalTest.php     | 24 +++++++++++++++++++
 2 files changed, 42 insertions(+), 2 deletions(-)

diff --git a/src/GeneratedHydrator/CodeGenerator/Visitor/HydratorMethodsVisitor.php b/src/GeneratedHydrator/CodeGenerator/Visitor/HydratorMethodsVisitor.php
index ce4f7391..3a6c7f98 100644
--- a/src/GeneratedHydrator/CodeGenerator/Visitor/HydratorMethodsVisitor.php
+++ b/src/GeneratedHydrator/CodeGenerator/Visitor/HydratorMethodsVisitor.php
@@ -110,9 +110,14 @@ private function generatePropertyHydrateCall(ObjectProperty $property, string $i
             return ['$object->' . $propertyName . ' = ' . $inputArrayName . '[' . $escapedName . '] ?? null;'];
         }
 
+        $nullCheck = '    || $object->' . $propertyName . ' !== null && \\array_key_exists(' . $escapedName . ', ' . $inputArrayName . ')';
+        if ($property->hasType) {
+            $nullCheck = '    || isset($object->' . $propertyName . ') && $object->' . $propertyName . ' !== null && \\array_key_exists(' . $escapedName . ', ' . $inputArrayName . ')';
+        }
+
         return [
             'if (isset(' . $inputArrayName . '[' . $escapedName . '])',
-            '    || $object->' . $propertyName . ' !== null && \\array_key_exists(' . $escapedName . ', ' . $inputArrayName . ')',
+            $nullCheck,
             ') {',
             '    $object->' . $propertyName . ' = ' . $inputArrayName . '[' . $escapedName . '];',
             '}',
@@ -141,7 +146,18 @@ private function replaceConstructor(ClassMethod $method): void
             $bodyParts[] = '$this->extractCallbacks[] = \\Closure::bind(static function ($object, &$values) {';
             foreach ($properties as $property) {
                 $propertyName = $property->name;
-                $bodyParts[]  = "    \$values['" . $propertyName . "'] = \$object->" . $propertyName . ';';
+                $requiresGuard = $property->hasType && !($property->hasDefault || $property->allowsNull);
+                $indent = $requiresGuard ? '        ' : '    ';
+
+                if ($requiresGuard) {
+                    $bodyParts[] = '    if (isset($object->' . $propertyName . ')) {';
+                }
+
+                $bodyParts[]  = $indent . "\$values['" . $propertyName . "'] = \$object->" . $propertyName . ';';
+
+                if ($requiresGuard) {
+                    $bodyParts[] = '    }';
+                }
             }
 
             $bodyParts[] = '}, null, ' . var_export($className, true) . ');' . "\n";
diff --git a/tests/GeneratedHydratorTest/Functional/HydratorFunctionalTest.php b/tests/GeneratedHydratorTest/Functional/HydratorFunctionalTest.php
index 0c5c4ca9..28deb8fb 100644
--- a/tests/GeneratedHydratorTest/Functional/HydratorFunctionalTest.php
+++ b/tests/GeneratedHydratorTest/Functional/HydratorFunctionalTest.php
@@ -100,6 +100,30 @@ public function testHydratorWillNotRaisedUnitiliazedTypedPropertyAccessError():
         ], $hydrator->extract($instance));
     }
 
+    /**
+     * Ensures that the hydrator will not attempt to read unitialized PHP >= 7.4
+     * typed property, which would cause "Uncaught Error: Typed property Foo::$a
+     * must not be accessed before initialization" PHP engine errors.
+     *
+     * @requires PHP >= 7.4
+     */
+    public function testHydratorWillNotRaisedUnitiliazedTypedPropertyAccessErrorIfPropertyIsntHydrated(): void
+    {
+        $instance = new ClassWithTypedProperties();
+        $hydrator = $this->generateHydrator($instance);
+
+        $hydrator->hydrate(['untyped0' => 3], $instance);
+
+        self::assertSame([
+            'property0' => 1, // 'property0' has a default value, it should keep it.
+            'property1' => 2, // 'property1' has a default value, it should keep it.
+            'property3' => null, // 'property3' is not required, it should remain null.
+            'property4' => null, // 'property4' default value is null, it should remain null.
+            'untyped0' => 3, // 'untyped0' is null by default
+            'untyped1' => null, // 'untyped1' is null by default
+        ], $hydrator->extract($instance));
+    }
+
     /** @requires PHP >= 7.4 */
     public function testHydratorWillSetAllTypedProperties(): void
     {