diff --git a/phpunit/code/property-default-array-for-int.php b/phpunit/code/property-default-array-for-int.php
new file mode 100644
index 00000000..6a5d56fe
--- /dev/null
+++ b/phpunit/code/property-default-array-for-int.php
@@ -0,0 +1,16 @@
+<?php
+
+class PropertyDefaultArrayForInt
+{
+    private int $a = [];
+
+    public function __construct()
+    {
+        var_dump($this->a);
+    }
+}
+
+function property_default_array_for_int(): void
+{
+    $test = new PropertyDefaultArrayForInt();
+}
diff --git a/phpunit/code/property-default-array-for-object.php b/phpunit/code/property-default-array-for-object.php
new file mode 100644
index 00000000..89d348b2
--- /dev/null
+++ b/phpunit/code/property-default-array-for-object.php
@@ -0,0 +1,15 @@
+<?php
+
+class PropertyDefaultArrayForObjectDep
+{
+}
+
+class PropertyDefaultArrayForObject
+{
+    public PropertyDefaultArrayForObjectDep $dep = [];
+}
+
+function property_default_array_for_object(): void
+{
+    $test = new PropertyDefaultArrayForObject();
+}
diff --git a/phpunit/code/property-default-class-const-type.php b/phpunit/code/property-default-class-const-type.php
new file mode 100644
index 00000000..fb5789be
--- /dev/null
+++ b/phpunit/code/property-default-class-const-type.php
@@ -0,0 +1,12 @@
+<?php
+
+class PropertyDefaultClassConstType
+{
+    public int $value = self::DEFAULT_VALUE;
+
+    private const DEFAULT_VALUE = 'invalid';
+}
+
+function main(): void
+{
+}
diff --git a/phpunit/code/property-default-expression-type.php b/phpunit/code/property-default-expression-type.php
new file mode 100644
index 00000000..78c031a6
--- /dev/null
+++ b/phpunit/code/property-default-expression-type.php
@@ -0,0 +1,10 @@
+<?php
+
+class PropertyDefaultExpressionType
+{
+    public int $value = 1.5 + 2;
+}
+
+function main(): void
+{
+}
diff --git a/phpunit/code/property-default-false-for-true.php b/phpunit/code/property-default-false-for-true.php
new file mode 100644
index 00000000..7643be27
--- /dev/null
+++ b/phpunit/code/property-default-false-for-true.php
@@ -0,0 +1,10 @@
+<?php
+
+class PropertyDefaultFalseForTrue
+{
+    public true $value = false;
+}
+
+function main(): void
+{
+}
diff --git a/phpunit/code/property-default-null-for-int.php b/phpunit/code/property-default-null-for-int.php
new file mode 100644
index 00000000..4431e760
--- /dev/null
+++ b/phpunit/code/property-default-null-for-int.php
@@ -0,0 +1,11 @@
+<?php
+
+class PropertyDefaultNullForInt
+{
+    public int $a = null;
+}
+
+function property_default_null_for_int(): void
+{
+    $test = new PropertyDefaultNullForInt();
+}
diff --git a/phpunit/code/property-default-string-for-int.php b/phpunit/code/property-default-string-for-int.php
new file mode 100644
index 00000000..11628ffe
--- /dev/null
+++ b/phpunit/code/property-default-string-for-int.php
@@ -0,0 +1,11 @@
+<?php
+
+class PropertyDefaultStringForInt
+{
+    public int $a = 'hello';
+}
+
+function property_default_string_for_int(): void
+{
+    $test = new PropertyDefaultStringForInt();
+}
diff --git a/phpunit/code/property-default-true-for-false.php b/phpunit/code/property-default-true-for-false.php
new file mode 100644
index 00000000..e88e8ca4
--- /dev/null
+++ b/phpunit/code/property-default-true-for-false.php
@@ -0,0 +1,10 @@
+<?php
+
+class PropertyDefaultTrueForFalse
+{
+    public false $value = true;
+}
+
+function main(): void
+{
+}
diff --git a/phpunit/code/property-default-valid.php b/phpunit/code/property-default-valid.php
new file mode 100644
index 00000000..9587b78f
--- /dev/null
+++ b/phpunit/code/property-default-valid.php
@@ -0,0 +1,23 @@
+<?php
+
+class PropertyDefaultValid
+{
+    public int $i = 123;
+    public float $f = 1.5;
+    public float $fromInt = 3;
+    public string $s = 'hello';
+    public bool $b = true;
+    public array $arr = [];
+    public ?int $ni = null;
+    public int|array $ia = [];
+    public mixed $m = [];
+    public $untyped = [];
+    public const NUM = 7;
+    public int $fromConst = self::NUM;
+}
+
+function property_default_valid(): void
+{
+    $test = new PropertyDefaultValid();
+    var_dump($test->i);
+}
diff --git a/phpunit/src/ClassTest.php b/phpunit/src/ClassTest.php
index 49d62cc6..a997fcb7 100644
--- a/phpunit/src/ClassTest.php
+++ b/phpunit/src/ClassTest.php
@@ -194,4 +194,74 @@ class ClassTest extends \BaseTest
         // 作为函数/方法默认参数值应当能够在编译期正确解析。
         $this->compile('class-const-default-value.php');
     }
+
+    public function testPropertyDefaultArrayForIntTypeFailsAtCompileTime()
+    {
+        $this->exec(
+            'Cannot use array as default value for property PropertyDefaultArrayForInt::$a of type int',
+            'property-default-array-for-int.php'
+        );
+    }
+
+    public function testPropertyDefaultStringForIntTypeFailsAtCompileTime()
+    {
+        $this->exec(
+            'Cannot use string as default value for property PropertyDefaultStringForInt::$a of type int',
+            'property-default-string-for-int.php'
+        );
+    }
+
+    public function testPropertyDefaultNullForNonNullableIntFailsAtCompileTime()
+    {
+        $this->exec(
+            'Cannot use null as default value for property PropertyDefaultNullForInt::$a of type int',
+            'property-default-null-for-int.php'
+        );
+    }
+
+    public function testPropertyDefaultArrayForObjectTypeFailsAtCompileTime()
+    {
+        $this->exec(
+            'Cannot use array as default value for property PropertyDefaultArrayForObject::$dep of type PropertyDefaultArrayForObjectDep',
+            'property-default-array-for-object.php'
+        );
+    }
+
+    public function testValidPropertyDefaultsCompile()
+    {
+        // 合法的默认值（含 int→float 协变、nullable、联合类型、mixed、常量）应通过检查。
+        $this->compile('property-default-valid.php');
+    }
+
+    public function testTrueDefaultForFalsePropertyFailsAtCompileTime()
+    {
+        $this->exec(
+            'Cannot use true as default value for property PropertyDefaultTrueForFalse::$value of type false',
+            'property-default-true-for-false.php'
+        );
+    }
+
+    public function testFalseDefaultForTruePropertyFailsAtCompileTime()
+    {
+        $this->exec(
+            'Cannot use false as default value for property PropertyDefaultFalseForTrue::$value of type true',
+            'property-default-false-for-true.php'
+        );
+    }
+
+    public function testClassConstantPropertyDefaultTypeFailsAtCompileTime()
+    {
+        $this->exec(
+            'Cannot use string as default value for property PropertyDefaultClassConstType::$value of type int',
+            'property-default-class-const-type.php'
+        );
+    }
+
+    public function testExpressionPropertyDefaultTypeFailsAtCompileTime()
+    {
+        $this->exec(
+            'Cannot use float as default value for property PropertyDefaultExpressionType::$value of type int',
+            'property-default-expression-type.php'
+        );
+    }
 }
diff --git a/src/Preprocessor.php b/src/Preprocessor.php
index b65cea84..612906d6 100644
--- a/src/Preprocessor.php
+++ b/src/Preprocessor.php
@@ -21,6 +21,7 @@ use TypePhp\Exception\SyntaxError;
 use TypePhp\Transform\PropertyHookLowering;
 use TypePhp\Transform\Visitor;
 use PhpParser\Modifiers;
+use PhpParser\ConstExprEvaluator;
 use PhpParser\Node;
 use PhpParser\Node\IntersectionType;
 use PhpParser\Node\NullableType;
@@ -620,12 +621,20 @@ class Preprocessor extends CompilerBase
         }
         $this->symbolDeclInFile[$fullClassNameLower] = $this->file;
 
+        // Property defaults may reference class constants declared later in the
+        // class body. Collect every constant first so default-value validation
+        // is independent of declaration order, matching PHP's class semantics.
+        foreach ($class->stmts as $stmt) {
+            if ($stmt instanceof Node\Stmt\ClassConst) {
+                $this->parseClassConstDef($stmt);
+            }
+        }
+
         $code = '';
         foreach ($class->stmts as $v) {
             $type = $v->getType();
             switch ($type) {
                 case 'Stmt_ClassConst':
-                    $this->parseClassConstDef($v);
                     break;
                 case 'Stmt_Property':
                     $this->parseClassPropertyDef($v);
@@ -891,10 +900,18 @@ class Preprocessor extends CompilerBase
         $default = null;
         $arrayInitPlan = null;
         if ($defaultNode !== null) {
+            $this->checkPropertyDefaultType($name, $typeNode, $defaultNode, $errorNode);
             if ($defaultNode instanceof Node\Expr\Array_) {
-                $type = Type::ARRAY;
                 $arrayInitPlan = $this->buildLiteralArrayInitPlan($defaultNode);
                 $default = $arrayInitPlan->expr;
+                // Only narrow the property type to `array` when the declared type
+                // cannot already hold an array. `mixed`/`iterable`/union/nullable
+                // types are represented as php::Var and can legally store an array,
+                // so forcing `array` here would wrongly reject non-array assignments
+                // (e.g. `mixed $value = []` followed by `$this->value = 123`).
+                if ($type !== Type::VAR) {
+                    $type = Type::ARRAY;
+                }
             } else {
                 $default = $this->parseIdentifier($defaultNode);
             }
@@ -918,6 +935,205 @@ class Preprocessor extends CompilerBase
         return $propDef;
     }
 
+    /**
+     * Diagnose, during preprocessing, whether a property's default value is
+     * compatible with its declared type.
+     *
+     * TypePHP rejects obvious mismatches such as `int $a = []` at compile time
+     * instead of silently coercing the declared type or deferring to a runtime
+     * TypeError, matching the static-compilation principles in CLAUDE.md.
+     */
+    protected function checkPropertyDefaultType(string $name, ?NodeAbstract $typeNode, NodeAbstract $defaultNode, NodeAbstract $errorNode): void
+    {
+        if ($typeNode === null) {
+            // Untyped property accepts any default value.
+            return;
+        }
+
+        $valueType = $this->detectDefaultValueType($defaultNode);
+        if ($valueType === null) {
+            // The value type is not statically decidable (e.g. user or class
+            // constant references); leave it to later stages.
+            return;
+        }
+
+        $allowed = $this->collectAllowedDefaultTypes($typeNode);
+        if ($allowed === null) {
+            // mixed / callable / otherwise unconstrained type declaration.
+            return;
+        }
+
+        if (in_array($valueType, $allowed, true)) {
+            return;
+        }
+
+        $className = $this->getFullClassName();
+        $typeStr   = $this->propertyTypeDeclToString($typeNode);
+        $this->fatalError(
+            $errorNode,
+            "Cannot use {$valueType} as default value for property {$className}::\${$name} of type {$typeStr}"
+        );
+    }
+
+    /**
+     * Determine the PHP value type of a constant expression used as a default
+     * value. Returns one of int/float/string/true/false/array/null, or null when
+     * the type cannot be decided statically.
+     */
+    protected function detectDefaultValueType(NodeAbstract $node, ?string $scopeClass = null, int $depth = 0): ?string
+    {
+        if ($depth > 16) {
+            return null;
+        }
+        $scopeClass ??= $this->getFullClassName();
+
+        switch ($node->getType()) {
+            case 'Scalar_Int':
+                return 'int';
+            case 'Scalar_Float':
+                return 'float';
+            case 'Scalar_String':
+            case 'Scalar_InterpolatedString':
+            case 'Expr_BinaryOp_Concat':
+                return 'string';
+            case 'Expr_Array':
+                return 'array';
+            case 'Expr_UnaryMinus':
+            case 'Expr_UnaryPlus':
+                return $this->detectDefaultValueType($node->expr, $scopeClass, $depth + 1);
+            case 'Expr_ConstFetch':
+                return match (strtolower($node->name->toString())) {
+                    'true'          => 'true',
+                    'false'         => 'false',
+                    'null'          => 'null',
+                    default         => null,
+                };
+            case 'Expr_ClassConstFetch':
+                if (!$node->class instanceof Node\Name || !$node->name instanceof Node\Identifier) {
+                    return null;
+                }
+                $constName = $node->name->toString();
+                if (strcasecmp($constName, 'class') === 0) {
+                    return 'string';
+                }
+                $className = $node->class->toString();
+                if (strcasecmp($className, 'self') === 0 || strcasecmp($className, 'static') === 0) {
+                    $targetClass = $scopeClass;
+                } elseif (strcasecmp($className, 'parent') === 0) {
+                    $targetClass = $this->getParentClass($scopeClass);
+                } else {
+                    $targetClass = $this->getNamespacedClassName($className);
+                }
+                if ($targetClass === '' || !$this->hasClass($targetClass)) {
+                    return null;
+                }
+                $targetDef = $this->getClass($targetClass);
+                if (!$targetDef->hasConstant($constName)) {
+                    return null;
+                }
+                return $this->detectDefaultValueType(
+                    $targetDef->getConstant($constName)->valueExpr,
+                    $targetClass,
+                    $depth + 1
+                );
+            default:
+                try {
+                    $value = (new ConstExprEvaluator(
+                        static function (Node\Expr $expr): never {
+                            throw new \RuntimeException('Unresolved constant expression');
+                        }
+                    ))->evaluateDirectly($node);
+                } catch (\Throwable) {
+                    return null;
+                }
+                return match (true) {
+                    is_int($value) => 'int',
+                    is_float($value) => 'float',
+                    is_string($value) => 'string',
+                    $value === true => 'true',
+                    $value === false => 'false',
+                    is_array($value) => 'array',
+                    $value === null => 'null',
+                    default => null,
+                };
+        }
+    }
+
+    /**
+     * Collect the set of value types accepted as a default for a declared type
+     * node. Returns null when the type imposes no statically-checkable
+     * constraint (mixed / callable / unknown).
+     *
+     * @return array<int, string>|null
+     */
+    protected function collectAllowedDefaultTypes(NodeAbstract $typeNode): ?array
+    {
+        if ($typeNode instanceof NullableType) {
+            $inner = $this->collectAllowedDefaultTypes($typeNode->type);
+            if ($inner === null) {
+                return null;
+            }
+            return array_values(array_unique(array_merge($inner, ['null'])));
+        }
+
+        if ($typeNode instanceof UnionType) {
+            $all = [];
+            foreach ($typeNode->types as $sub) {
+                $part = $this->collectAllowedDefaultTypes($sub);
+                if ($part === null) {
+                    // A mixed-like member accepts any default value.
+                    return null;
+                }
+                $all = array_merge($all, $part);
+            }
+            return array_values(array_unique($all));
+        }
+
+        if ($typeNode instanceof IntersectionType) {
+            // Intersection types are object-only; no scalar/array default valid.
+            return [];
+        }
+
+        return match (strtolower($this->parseIdentifier($typeNode))) {
+            'int'                      => ['int'],
+            'float', 'double'          => ['float', 'int'], // int coerces to float
+            'string'                   => ['string'],
+            'bool'                     => ['true', 'false'],
+            'true'                     => ['true'],
+            'false'                    => ['false'],
+            'array'                    => ['array'],
+            'iterable'                 => ['array'],
+            'null'                     => ['null'],
+            'object'                   => [], // no literal object default exists
+            'self', 'parent', 'static' => [],
+            'mixed'                    => null,
+            'callable'                 => null, // string/array/closure — not checkable
+            default                    => [],   // class type: only null via ?Type
+        };
+    }
+
+    protected function propertyTypeDeclToString(NodeAbstract $typeNode): string
+    {
+        if ($typeNode instanceof NullableType) {
+            return '?' . $this->propertyTypeDeclToString($typeNode->type);
+        }
+        if ($typeNode instanceof UnionType) {
+            $parts = [];
+            foreach ($typeNode->types as $t) {
+                $parts[] = $this->propertyTypeDeclToString($t);
+            }
+            return implode('|', $parts);
+        }
+        if ($typeNode instanceof IntersectionType) {
+            $parts = [];
+            foreach ($typeNode->types as $t) {
+                $parts[] = $this->propertyTypeDeclToString($t);
+            }
+            return implode('&', $parts);
+        }
+        return $this->parseIdentifier($typeNode);
+    }
+
     protected function parseClassPropertyDef(Node\Stmt\Property $v): void
     {
         $oriCtx = $this->context;
diff --git a/src/Translator.php b/src/Translator.php
index 1f15eca3..3b1950de 100644
--- a/src/Translator.php
+++ b/src/Translator.php
@@ -866,15 +866,36 @@ CODE;
 
         $code .= '// static property ' . PHP_EOL;
         foreach ($this->symbols->classes() as $classDef) {
+            // Traits are never instantiated on their own; their static properties
+            // live on the classes that use them (where the members are flattened).
+            // Initialising a default on the trait itself would write to the trait's
+            // static property table and, on PHP >= 8.3, trigger a
+            // "Accessing static trait property" deprecation when the value is read
+            // through `self::` from a consuming class. Skip traits here; the
+            // consuming classes still initialise their own (flattened) copies.
+            if ($classDef->trait) {
+                continue;
+            }
             foreach ($classDef->properties as $property) {
-                if (!$property->isStatic() || !$property->arrayInitPlan || !$property->default) {
+                if (!$property->isStatic() || $property->default === null) {
                     continue;
                 }
-                $statement = 'php::setStaticProperty('
-                    . $this->genCharPtr($classDef->getNamespacedName(false), true) . ', '
-                    . $this->genCharPtr($property->name) . ', '
-                    . $property->arrayInitPlan->expr . ');' . PHP_EOL;
-                $code .= $this->wrapArrayInitPlan($property->arrayInitPlan, $statement);
+                if ($property->arrayInitPlan) {
+                    $statement = 'php::setStaticProperty('
+                        . $this->genCharPtr($classDef->getNamespacedName(false), true) . ', '
+                        . $this->genCharPtr($property->name) . ', '
+                        . $property->arrayInitPlan->expr . ');' . PHP_EOL;
+                    $code .= $this->wrapArrayInitPlan($property->arrayInitPlan, $statement);
+                } else {
+                    $default = $property->type === Type::FLOAT
+                        ? $this->convertFloatExpr($property->default)
+                        : $property->default;
+                    $statement = 'php::setStaticProperty('
+                        . $this->genCharPtr($classDef->getNamespacedName(false), true) . ', '
+                        . $this->genCharPtr($property->name) . ', '
+                        . 'php::Var(' . $default . '));' . PHP_EOL;
+                    $code .= $statement;
+                }
             }
         }
 
@@ -1609,19 +1630,63 @@ CODE;
             if ($classDef && !$classDef->trait && !$classDef->enum) {
                 $className = $classDef->getNamespacedName();
                 $handlers = "property_handlers_{$className}";
-                $buildCreateBody = function (bool $attachHandlers) use ($classDef, $className, $handlers): string {
+                $initBlock = '';
+                foreach ($classDef->properties as $property) {
+                    if ($property->isStatic() || $property->default === null) {
+                        continue;
+                    }
+                    if ($property->arrayInitPlan) {
+                        $init = "auto value = {$property->arrayInitPlan->expr};\n";
+                        $init .= 'zend_update_property(obj->ce, obj, ' . $this->genZendStrl($property->name) . ", value.ptr());\n";
+                        $init .= "php::throwErrorIfOccurred();\n";
+                        $initBlock .= $this->wrapArrayInitPlan($property->arrayInitPlan, $init);
+                    } else {
+                        // Scalar / constant / null default value. Wrap it in a
+                        // php::Var so it can be stored as a zval in the object's
+                        // property table via zend_update_property. Each property is
+                        // wrapped in its own block so the local `value` does not
+                        // clash with siblings declared in the same create_object body.
+                        $default = $property->type === Type::FLOAT
+                            ? $this->convertFloatExpr($property->default)
+                            : $property->default;
+                        $init = "do {\n";
+                        $init .= "auto value = php::Var({$default});\n";
+                        $init .= 'zend_update_property(obj->ce, obj, ' . $this->genZendStrl($property->name) . ", value.ptr());\n";
+                        $init .= "php::throwErrorIfOccurred();\n";
+                        $init .= "} while (0);\n";
+                        $initBlock .= $init;
+                    }
+                }
+
+                $buildCreateBody = function (bool $attachHandlers) use ($classDef, $className, $handlers, $ce, $initBlock): string {
                     $body = $classDef->ctorInit;
-                    $body .= "auto obj = create_object_{$className}(class_type);\n";
                     if ($attachHandlers) {
+                        // PHP < 8.4: the custom handlers are attached to the object
+                        // AFTER the standard create_object, so object_properties_init
+                        // runs with the standard handlers (no asymmetric check). Our
+                        // explicit default inits run with the custom handlers
+                        // attached, so we set EG(fake_scope) to the object's own class
+                        // to satisfy asymmetric visibility for the class's own
+                        // properties.
+                        $body .= "auto obj = create_object_{$className}(class_type);\n";
                         $body .= "typephp_attach_property_handlers(obj, &{$handlers});\n";
-                    }
-                    foreach ($classDef->properties as $property) {
-                        if (!$property->isStatic() && $property->arrayInitPlan && $property->default) {
-                            $init = "auto value = {$property->arrayInitPlan->expr};\n";
-                            $init .= 'zend_update_property(obj->ce, obj, ' . $this->genZendStrl($property->name) . ", value.ptr());\n";
-                            $init .= "php::throwErrorIfOccurred();\n";
-                            $body .= $this->wrapArrayInitPlan($property->arrayInitPlan, $init);
-                        }
+                        $body .= "zend_class_entry *__typephp_saved_fake_scope = EG(fake_scope);\n";
+                        $body .= "EG(fake_scope) = obj->ce;\n";
+                        $body .= $initBlock;
+                        $body .= "EG(fake_scope) = __typephp_saved_fake_scope;\n";
+                    } else {
+                        // PHP >= 8.4: the custom handlers live in
+                        // default_object_handlers, so the object already carries the
+                        // asymmetric write_property hook at creation time and
+                        // object_properties_init would reject private(set)/protected(set)
+                        // default values (including inherited ones). Create the object
+                        // with the standard handlers, run the default initialization
+                        // (no visibility check), then attach the custom handlers.
+                        $body .= "auto obj = zend_objects_new(class_type);\n";
+                        $body .= "obj->handlers = const_cast<zend_object_handlers *>(zend_get_std_object_handlers());\n";
+                        $body .= "object_properties_init(obj, class_type);\n";
+                        $body .= $initBlock;
+                        $body .= "obj->handlers = &{$handlers};\n";
                     }
                     $body .= $classDef->ctorClean;
                     return $body . "return obj;\n";
@@ -1633,7 +1698,7 @@ CODE;
                 $code .= "{$ce}->create_object = [](zend_class_entry *class_type) -> zend_object* {\n";
                 $code .= $buildCreateBody(true);
                 $code .= "};\n";
-                if ($classDef->requireCtor) {
+                if ($classDef->requireCtor || $this->classHasAsymmetricOrHookedProperty($classDef)) {
                     $code .= "#else\n";
                     $code .= "create_object_{$className} = php_get_create_object_fn({$ce});\n";
                     $code .= "{$ce}->create_object = [](zend_class_entry *class_type) -> zend_object* {\n";
@@ -1646,6 +1711,46 @@ CODE;
         return $code;
     }
 
+    /**
+     * Whether the given class (or any of its ancestors) declares an asymmetric
+     * visibility property (private(set)/protected(set)) or a hooked property
+     * (getter/setter). Such classes install a custom write_property handler, and
+     * on PHP >= 8.4 that handler lives in the class's default object handlers, so
+     * the engine's object_properties_init would reject inherited default values
+     * unless we generate our own create_object that initializes with the standard
+     * handlers first.
+     */
+    private function classHasAsymmetricOrHookedProperty(ClassDef $classDef): bool
+    {
+        $current = $classDef;
+        $seen = [];
+        while ($current !== null) {
+            $key = strtolower(ltrim($current->getNamespacedName(), '\\'));
+            if (isset($seen[$key])) {
+                break;
+            }
+            $seen[$key] = true;
+            foreach ($current->properties as $property) {
+                if ($property->isPrivateSet()
+                    || $property->isProtectedSet()
+                    || $property->getter !== null
+                    || $property->setter !== null
+                ) {
+                    return true;
+                }
+            }
+            if (!$current->extends) {
+                break;
+            }
+            $parent = $this->getClassDef($current->extends);
+            if ($parent === null) {
+                break;
+            }
+            $current = $parent;
+        }
+        return false;
+    }
+
     protected function getRegisterClassFunction(string $name): string
     {
         return self::PREFIX . 'register_class_' . $name;
@@ -2884,13 +2989,13 @@ CODE;
 
         // 接口没有方法实体
         if ($classDef instanceof ClassDef) {
-            $arrayPropCount = 0;
+            $defaultPropCount = 0;
             foreach ($classDef->properties as $property) {
-                if ($property->type === Type::ARRAY && $property->arrayInitPlan && $property->default && !$property->isStatic()) {
-                    $arrayPropCount++;
+                if (!$property->isStatic() && $property->default !== null) {
+                    $defaultPropCount++;
                 }
             }
-            if ($arrayPropCount > 0) {
+            if ($defaultPropCount > 0) {
                 $classDef->requireCtor = true;
             }
             $methods = $classDef->methods;
diff --git a/src/gen_stub.php b/src/gen_stub.php
index 752c6b9b..c19ee29a 100755
--- a/src/gen_stub.php
+++ b/src/gen_stub.php
@@ -2371,12 +2371,16 @@ class EvaluatedValue
                     if ($class === 'self') {
                         $constName = ClassInfo::$currentClass . "::" . $constName;
                         if (isset($allConstInfos[$constName])) {
-                            return formatConstValue($allConstInfos[$constName]->getValue($allConstInfos)->value);
+                            return $allConstInfos[$constName]->getValue($allConstInfos)->value;
                         } else {
-                            return formatConstValue(getTranslator()->getClassConstValue($expr, ClassInfo::$currentClass, $constName));
+                            return normalizeConstExprValue(
+                                getTranslator()->getClassConstValue($expr, ClassInfo::$currentClass, $constName)
+                            );
                         }
                     } else {
-                        return formatConstValue(getTranslator()->getClassConstValue($expr, $class, $constName, ClassInfo::$currentClass));
+                        return normalizeConstExprValue(
+                            getTranslator()->getClassConstValue($expr, $class, $constName, ClassInfo::$currentClass)
+                        );
                     }
                 } else {
                     $constName = $expr->name->__toString();
@@ -2414,7 +2418,7 @@ class EvaluatedValue
                 if (isset($definedConstants[$constName])) {
                     $constValue = $definedConstants[$constName];
                     if (is_scalar($constValue)) {
-                        return formatConstValue($constValue);
+                        return $constValue;
                     }
                 }
 
@@ -2508,11 +2512,15 @@ class EvaluatedValue
                     // fully qualified class name (already stored in $this->value).
                     return '"' . addcslashes($this->value, '\\') . '"';
                 }
-                return $this->value;
+                return '"' . getTranslator()->escapeString((string) $this->value) . '"';
             } elseif ($this->expr instanceof Expr\ConstFetch) {
                 return getTranslator()->getConstValue($this->expr->name->toString());
             } elseif (!($this->expr instanceof String_)) {
-                throw new Exception("Expression at line " . $this->expr->getStartLine() . " must be a scalar string");
+                // ConstExprEvaluator has already reduced concatenations and
+                // other constant string expressions to their PHP value. Emit
+                // that value as a C string literal instead of rejecting every
+                // non-literal string expression.
+                return '"' . getTranslator()->escapeString((string) $this->value) . '"';
             }
             $expr = preg_replace("/(^'|'$)/", '"', getTranslator()->escapeString($expr));
         } elseif ($this->type->isInt() or $this->type->isFloat()) {
@@ -3306,6 +3314,11 @@ class PropertyInfo extends VariableLike
                 $defaultValue = EvaluatedValue::null();
             } else {
                 $defaultValue = EvaluatedValue::createFromExpression($this->defaultValue, null, null, $allConstInfos);
+                if ($simpleType !== null && $simpleType->isFloat() && $defaultValue->type->isInt()) {
+                    // PHP permits an integer default for a float property and
+                    // stores it as a double in the class default table.
+                    $defaultValue->type = $simpleType;
+                }
                 if ($defaultValue->isUnknownConstValue || ($defaultValue->originatingConsts && $defaultValue->getCExpr() === null)) {
                     echo "Skipping code generation for property $this->name, because it has an unknown constant default value\n";
                     return "";
@@ -6365,16 +6378,16 @@ function initPhpParser() {
     $isInitialized = true;
 }
 
-function formatConstValue(mixed $constValue)
+function normalizeConstExprValue(mixed $constValue): mixed
 {
-    if (is_string($constValue)) {
-        if (str_starts_with($constValue, '"') and str_ends_with($constValue, '"')) {
-            return $constValue;
-        }
-        return '"' . $constValue . '"';
-    } else {
-        return $constValue;
+    if (is_string($constValue)
+        && strlen($constValue) >= 2
+        && $constValue[0] === '"'
+        && $constValue[strlen($constValue) - 1] === '"'
+    ) {
+        return stripcslashes(substr($constValue, 1, -1));
     }
+    return $constValue;
 }
 
 function getTranslator(): Translator
diff --git a/tests/compiler/object_property/default-expressions-inheritance.phpt b/tests/compiler/object_property/default-expressions-inheritance.phpt
new file mode 100644
index 00000000..fc517d24
--- /dev/null
+++ b/tests/compiler/object_property/default-expressions-inheritance.phpt
@@ -0,0 +1,53 @@
+--TEST--
+Property defaults support constant expressions, inheritance, and traits
+--FILE--
+<?php
+
+const GLOBAL_NUMBER = 4;
+
+trait PropertyDefaultsTrait
+{
+    public int $traitValue = 10 + 1;
+    public static string $traitStatic = 'trait' . '-static';
+}
+
+class PropertyDefaultsParent
+{
+    private const LABEL_PREFIX = 'parent';
+
+    public int $sum = 1 + 2;
+    public float $ratio = 2;
+    protected string $label = self::LABEL_PREFIX . '-value';
+    public static int $counter = GLOBAL_NUMBER + 1;
+    public static float $staticRatio = 3;
+
+    public function label(): string
+    {
+        return $this->label;
+    }
+}
+
+class PropertyDefaultsChild extends PropertyDefaultsParent
+{
+    use PropertyDefaultsTrait;
+}
+
+function main(): void
+{
+    $value = new PropertyDefaultsChild();
+    var_dump($value->sum, $value->ratio, $value->label(), $value->traitValue);
+    var_dump(
+        PropertyDefaultsChild::$counter,
+        PropertyDefaultsChild::$staticRatio,
+        PropertyDefaultsChild::$traitStatic
+    );
+}
+?>
+--EXPECT--
+int(3)
+float(2)
+string(12) "parent-value"
+int(11)
+int(5)
+float(3)
+string(12) "trait-static"
diff --git a/tests/compiler/object_property/default-mixed-array.phpt b/tests/compiler/object_property/default-mixed-array.phpt
new file mode 100644
index 00000000..dbb4e883
--- /dev/null
+++ b/tests/compiler/object_property/default-mixed-array.phpt
@@ -0,0 +1,52 @@
+--TEST--
+property default value is array with mixed declared type
+--FILE--
+<?php
+
+declare(strict_types=1);
+
+class Test
+{
+    private mixed $value = [];
+
+    public function __construct(mixed $value)
+    {
+        $this->value = $value;
+    }
+
+    public function getValue(): mixed
+    {
+        return $this->value;
+    }
+}
+
+function main()
+{
+    $test = new Test(123);
+    var_dump($test->getValue());
+
+    $test = new Test('test');
+    var_dump($test->getValue());
+
+    $test = new Test([1, 2, 3]);
+    var_dump($test->getValue());
+
+    $test = new Test(new stdClass);
+    $v = $test->getValue();
+    var_dump($v instanceof stdClass);
+    var_dump(get_class($v));
+}
+?>
+--EXPECT--
+int(123)
+string(4) "test"
+array(3) {
+  [0]=>
+  int(1)
+  [1]=>
+  int(2)
+  [2]=>
+  int(3)
+}
+bool(true)
+string(8) "stdClass"
diff --git a/tests/compiler/object_property/default-values.phpt b/tests/compiler/object_property/default-values.phpt
new file mode 100644
index 00000000..a5adcb99
--- /dev/null
+++ b/tests/compiler/object_property/default-values.phpt
@@ -0,0 +1,55 @@
+--TEST--
+various property default values (array, int, float, string, bool, null, const)
+--FILE--
+<?php
+
+class Test
+{
+    public $untypedArray = [];
+    public mixed $mixedArray = [];
+    public array $typedArray = [];
+    public $untypedInt = 123;
+    public int $typedInt = 123;
+    public float $typedFloat = 1.5;
+    public string $typedString = 'hello';
+    public bool $typedBool = true;
+    public $untypedNull = null;
+    public $untypedConst = PHP_INT_MAX;
+
+    public function show(): void
+    {
+        var_dump(
+            $this->untypedArray,
+            $this->mixedArray,
+            $this->typedArray,
+            $this->untypedInt,
+            $this->typedInt,
+            $this->typedFloat,
+            $this->typedString,
+            $this->typedBool,
+            $this->untypedNull,
+            $this->untypedConst
+        );
+    }
+}
+
+function main()
+{
+    $t = new Test();
+    $t->show();
+}
+?>
+--EXPECT--
+array(0) {
+}
+array(0) {
+}
+array(0) {
+}
+int(123)
+int(123)
+float(1.5)
+string(5) "hello"
+bool(true)
+NULL
+int(9223372036854775807)