diff --git a/src/Php/ArgInfo.php b/src/Php/ArgInfo.php
index 680f1d33..70902959 100644
--- a/src/Php/ArgInfo.php
+++ b/src/Php/ArgInfo.php
@@ -23,6 +23,7 @@ class ArgInfo
     public bool $byRef = false;
     public bool $variadic = false;
     public bool $nullable = false;
+    public bool $undeclared = false;
     public bool $property = false;
 
     /**
diff --git a/src/Php/Entity/FunctionDef.php b/src/Php/Entity/FunctionDef.php
index ff98ccbc..2c520efc 100644
--- a/src/Php/Entity/FunctionDef.php
+++ b/src/Php/Entity/FunctionDef.php
@@ -25,6 +25,7 @@ class FunctionDef
     public string $namespace;
     public bool $method = false;
     public bool $stub = false;
+    public bool $returnTypeUndeclared = false;
 
     /**
      * @var string 必须是带有命名空间的完整类名
diff --git a/src/Php/MagicMethodDetector.php b/src/Php/MagicMethodDetector.php
index 0d32ea02..f7f8b2d6 100644
--- a/src/Php/MagicMethodDetector.php
+++ b/src/Php/MagicMethodDetector.php
@@ -16,53 +16,151 @@ trait MagicMethodDetector
     public function checkRequiredArgNum(string $name, MethodDef $methodDef, NodeAbstract $v): void
     {
         $argInfoList = $methodDef->functionDef->argInfoList;
-        $returnType = $methodDef->functionDef->returnType;
+        $fnDef = $methodDef->functionDef;
+        $returnTypeUndeclared = $fnDef->returnTypeUndeclared;
 
         $nameLower = strtolower($name);
 
-        if ($nameLower == '__call' or $nameLower == '__callstatic' or $nameLower == '__set') {
+        if ($nameLower == '__call' or $nameLower == '__callstatic') {
             if (count($argInfoList) != 2) {
                 $this->fatalError($v, 'Method ' . $this->class . "::{$name}() must take exactly 2 arguments");
             }
-            if (!$this->checkArgType($argInfoList[0]->type, self::TYPE_STR)) {
-                $this->fatalError($v, 'Method ' . $this->class . "::{$name}() must take string as argument");
+            if ($argInfoList[0]->undeclared) {
+                $argInfoList[0]->type = self::TYPE_STR;
+            } elseif ($argInfoList[0]->type !== self::TYPE_STR) {
+                $this->fatalError($v, 'Method ' . $this->class . "::{$name}() must take string as first argument");
+            }
+            if ($argInfoList[1]->undeclared) {
+                $argInfoList[1]->type = self::TYPE_ARRAY;
+            } elseif ($argInfoList[1]->type !== self::TYPE_ARRAY) {
+                $this->fatalError($v, 'Method ' . $this->class . "::{$name}() must take array as second argument");
+            }
+        } elseif ($nameLower == '__set') {
+            if (count($argInfoList) != 2) {
+                $this->fatalError($v, 'Method ' . $this->class . "::{$name}() must take exactly 2 arguments");
+            }
+            if ($argInfoList[0]->undeclared) {
+                $argInfoList[0]->type = self::TYPE_STR;
+            } elseif ($argInfoList[0]->type !== self::TYPE_STR) {
+                $this->fatalError($v, 'Method ' . $this->class . "::{$name}() must take string as first argument");
+            }
+            if ($returnTypeUndeclared) {
+                $fnDef->returnType = self::TYPE_VOID;
+            } elseif ($fnDef->returnType !== self::TYPE_VOID) {
+                $this->fatalError($v, 'Method ' . $this->class . "::{$name}() must return void");
             }
         } elseif ($nameLower == '__get') {
             if (count($argInfoList) != 1) {
                 $this->fatalError($v, 'Method ' . $this->class . "::{$name}() must take exactly 1 argument");
             }
         } elseif ($nameLower == '__tostring') {
-            if (!$this->checkArgType($returnType, self::TYPE_STR, false)) {
+            if ($returnTypeUndeclared) {
+                $fnDef->returnType = self::TYPE_STR;
+            } elseif ($fnDef->returnType !== self::TYPE_STR) {
                 $this->fatalError($v, 'Method ' . $this->class . "::{$name}() must return string");
             }
         } elseif ($nameLower == '__serialize') {
-            if (!$this->checkArgType($returnType, self::TYPE_ARRAY)) {
+            if ($returnTypeUndeclared) {
+                $fnDef->returnType = self::TYPE_ARRAY;
+            } elseif ($fnDef->returnType !== self::TYPE_ARRAY) {
                 $this->fatalError($v, 'Method ' . $this->class . "::{$name}() must return array");
             }
         } elseif ($nameLower == '__unserialize') {
             if (count($argInfoList) != 1) {
                 $this->fatalError($v, 'Method ' . $this->class . "::{$name}() must take exactly 1 argument");
             }
-            if (!$this->checkArgType($argInfoList[0]->type, self::TYPE_ARRAY)) {
+            if ($argInfoList[0]->undeclared) {
+                $argInfoList[0]->type = self::TYPE_ARRAY;
+            } elseif ($argInfoList[0]->type !== self::TYPE_ARRAY) {
                 $this->fatalError($v, 'Method ' . $this->class . "::{$name}() must take array as argument");
             }
-        } elseif ($nameLower == '__isset' or $nameLower == '__unset' or $nameLower == '__set_state') {
+            if ($returnTypeUndeclared) {
+                $fnDef->returnType = self::TYPE_VOID;
+            } elseif ($fnDef->returnType !== self::TYPE_VOID) {
+                $this->fatalError($v, 'Method ' . $this->class . "::{$name}() must return void");
+            }
+        } elseif ($nameLower == '__isset') {
             if (count($argInfoList) != 1) {
                 $this->fatalError($v, 'Method ' . $this->class . "::{$name}() must take exactly 1 argument");
             }
-            if (!$this->checkArgType($argInfoList[0]->type, self::TYPE_STR)) {
+            if ($argInfoList[0]->undeclared) {
+                $argInfoList[0]->type = self::TYPE_STR;
+            } elseif ($argInfoList[0]->type !== self::TYPE_STR) {
                 $this->fatalError($v, 'Method ' . $this->class . "::{$name}() must take string as argument");
             }
-            if ($nameLower == '__set_state') {
-                if (!$this->checkArgType($returnType, self::TYPE_ARRAY)) {
-                    $this->fatalError($v, 'Method ' . $this->class . "::{$name}() must return array");
-                }
+            if ($returnTypeUndeclared) {
+                $fnDef->returnType = self::TYPE_BOOL;
+            } elseif ($fnDef->returnType !== self::TYPE_BOOL) {
+                $this->fatalError($v, 'Method ' . $this->class . "::{$name}() must return bool");
+            }
+        } elseif ($nameLower == '__unset') {
+            if (count($argInfoList) != 1) {
+                $this->fatalError($v, 'Method ' . $this->class . "::{$name}() must take exactly 1 argument");
+            }
+            if ($argInfoList[0]->undeclared) {
+                $argInfoList[0]->type = self::TYPE_STR;
+            } elseif ($argInfoList[0]->type !== self::TYPE_STR) {
+                $this->fatalError($v, 'Method ' . $this->class . "::{$name}() must take string as argument");
+            }
+            if ($returnTypeUndeclared) {
+                $fnDef->returnType = self::TYPE_VOID;
+            } elseif ($fnDef->returnType !== self::TYPE_VOID) {
+                $this->fatalError($v, 'Method ' . $this->class . "::{$name}() must return void");
+            }
+        } elseif ($nameLower == '__set_state') {
+            if (count($argInfoList) != 1) {
+                $this->fatalError($v, 'Method ' . $this->class . "::{$name}() must take exactly 1 argument");
+            }
+            if ($argInfoList[0]->undeclared) {
+                $argInfoList[0]->type = self::TYPE_ARRAY;
+            } elseif ($argInfoList[0]->type !== self::TYPE_ARRAY) {
+                $this->fatalError($v, 'Method ' . $this->class . "::{$name}() must take array as argument");
+            }
+            if ($returnTypeUndeclared) {
+                $fnDef->returnType = self::TYPE_OBJECT;
+            } elseif ($fnDef->returnType !== self::TYPE_OBJECT) {
+                $this->fatalError($v, 'Method ' . $this->class . "::{$name}() must return object");
             }
         } elseif ($nameLower == '__debuginfo') {
-            if (!$this->checkArgType($returnType, self::TYPE_ARRAY)) {
+            if ($returnTypeUndeclared) {
+                $fnDef->returnType = self::TYPE_ARRAY;
+            } elseif ($fnDef->returnType !== self::TYPE_ARRAY) {
+                $this->fatalError($v, 'Method ' . $this->class . "::{$name}() must return array");
+            }
+        } elseif ($nameLower == '__sleep') {
+            if ($returnTypeUndeclared) {
+                $fnDef->returnType = self::TYPE_ARRAY;
+            } elseif ($fnDef->returnType !== self::TYPE_ARRAY) {
                 $this->fatalError($v, 'Method ' . $this->class . "::{$name}() must return array");
             }
+        } elseif ($nameLower == '__wakeup') {
+            if ($returnTypeUndeclared) {
+                $fnDef->returnType = self::TYPE_VOID;
+            } elseif ($fnDef->returnType !== self::TYPE_VOID) {
+                $this->fatalError($v, 'Method ' . $this->class . "::{$name}() must return void");
+            }
+        } elseif ($nameLower == '__clone') {
+            if ($returnTypeUndeclared) {
+                $fnDef->returnType = self::TYPE_VOID;
+            } elseif ($fnDef->returnType !== self::TYPE_VOID) {
+                $this->fatalError($v, 'Method ' . $this->class . "::{$name}() must return void");
+            }
+        }
+
+        // 重建 params 字符串，使 C++ 函数签名使用 auto-fill 后的类型
+        $list = [];
+        foreach ($fnDef->argInfoList as $argInfo) {
+            if ($argInfo->variadic) {
+                $list[] = self::TYPE_ARRAY . ' ' . $argInfo->name;
+            } else {
+                $type = $argInfo->type;
+                if ($type === self::TYPE_STREAM || $type === self::TYPE_BOX) {
+                    $type = self::TYPE_VAR;
+                }
+                $list[] = $type . ' ' . $argInfo->name;
+            }
         }
+        $fnDef->params = implode(', ', $list);
     }
 
     protected function checkArgType(string $givenType, string $expectType, bool $canBeVar = true): bool
diff --git a/src/Php/Preprocessor.php b/src/Php/Preprocessor.php
index 4d2f3e35..81773edc 100644
--- a/src/Php/Preprocessor.php
+++ b/src/Php/Preprocessor.php
@@ -229,6 +229,7 @@ class Preprocessor extends CompilerBase
         }
         $class = '';
         $type = $this->parseTypeDecl($param->type, self::DECL_TYPE_OF_PARAM, $class);
+        $argInfo->undeclared = $param->type === null;
         if ($class and !$this->hasInterface($class) and !$this->isAbstractClass($class)) {
             $argInfo->class = $class;
         }
@@ -357,6 +358,7 @@ class Preprocessor extends CompilerBase
         $functionDef = new FunctionDef($fnName, $returnType, $this->namespace);
         $functionDef->returnClass = $class;
         $functionDef->stub = $this->stubFile;
+        $functionDef->returnTypeUndeclared = $v->returnType === null;
 
         if ($v->returnType instanceof NullableType or $v->returnType instanceof UnionType) {
             $typeInfo = $this->buildTypeCheckFromNode($v->returnType);
diff --git a/src/gen_stub.php b/src/gen_stub.php
index f7cac0f3..c314aba1 100755
--- a/src/gen_stub.php
+++ b/src/gen_stub.php
@@ -4809,6 +4809,51 @@ class FramelessFunctionInfo {
     }
 }
 
+/**
+ * 获取魔术方法的默认返回值类型。只有用户未显式声明类型时才使用。
+ */
+function getMagicMethodDefaultReturnType(FunctionOrMethodName $name): ?string
+{
+    if (!($name instanceof MethodName)) {
+        return null;
+    }
+    $map = [
+        '__set' => 'void',
+        '__tostring' => 'string',
+        '__serialize' => 'array',
+        '__unserialize' => 'void',
+        '__isset' => 'bool',
+        '__unset' => 'void',
+        '__set_state' => 'object',
+        '__debuginfo' => 'array',
+        '__sleep' => 'array',
+        '__wakeup' => 'void',
+        '__clone' => 'void',
+    ];
+    return $map[strtolower($name->methodName)] ?? null;
+}
+
+/**
+ * 获取魔术方法的默认参数类型。只有用户未显式声明类型时才使用。
+ */
+function getMagicMethodDefaultParamType(FunctionOrMethodName $name, int $index): ?string
+{
+    if (!($name instanceof MethodName)) {
+        return null;
+    }
+    $map = [
+        '__call' => ['string', 'array'],
+        '__callstatic' => ['string', 'array'],
+        '__set' => ['string'],
+        '__unserialize' => ['array'],
+        '__isset' => ['string'],
+        '__unset' => ['string'],
+        '__set_state' => ['array'],
+    ];
+    $methodParams = $map[strtolower($name->methodName)] ?? null;
+    return $methodParams[$index] ?? null;
+}
+
 function parseFunctionLike(
     PrettyPrinterAbstract $prettyPrinter,
     FunctionOrMethodName $name,
@@ -4930,7 +4975,8 @@ function parseFunctionLike(
 
             $type = $param->type ? Type::fromNode($param->type) : null;
             if ($type === null && !isset($docParamTypes[$varName])) {
-                $type = Type::fromString("mixed");
+                $defaultParamType = getMagicMethodDefaultParamType($name, $i);
+                $type = Type::fromString($defaultParamType ?? 'mixed');
             }
 
             if ($param->default instanceof Expr\ConstFetch &&
@@ -4974,7 +5020,7 @@ function parseFunctionLike(
 
         $returnType = $func->getReturnType();
         if ($returnType === null && $docReturnType === null && !$name->isConstructor() && !$name->isDestructor()) {
-            $docReturnType = "mixed";
+            $docReturnType = getMagicMethodDefaultReturnType($name) ?? 'mixed';
         }
 
         $return = new ReturnInfo(