diff --git a/examples/error/str.php b/examples/error/str.php
new file mode 100644
index 00000000..c83c38dd
--- /dev/null
+++ b/examples/error/str.php
@@ -0,0 +1,20 @@
+<?php
+class TestObject {
+    public string $a;
+    function __toString(): string
+    {
+        return $this->a;
+    }
+}
+function test(string $a)
+{
+    var_dump($a);
+}
+
+function main()
+{
+    $o = new TestObject();
+    $o->a = "hello";
+    test($o);
+}
+
diff --git a/examples/myext/test.php b/examples/myext/test.php
index b8b42c7b..7cb6f3f8 100644
--- a/examples/myext/test.php
+++ b/examples/myext/test.php
@@ -1,5 +1,12 @@
 <?php
 function my_add(int $a, int $b): int
 {
+    $env = $_ENV;
+    var_dump(count($env));
     return $a + $b;
+}
+
+function main()
+{
+    var_dump(my_add(1, 2));
 }
\ No newline at end of file
diff --git a/src/Php/CompilerBase.php b/src/Php/CompilerBase.php
index c6611f48..86c02e99 100644
--- a/src/Php/CompilerBase.php
+++ b/src/Php/CompilerBase.php
@@ -1377,14 +1377,8 @@ class CompilerBase extends \PhpAot\Core\Translator
                 }
                 if (!$this->hasVar($var)) {
                     $this->addLocalVar($var, $type);
-                } elseif (($this->getVarType($var) !== self::TYPE_VAR and $this->isTypedObject($var) and $type !== self::TYPE_OBJECT)
-                    // 禁止字符串与数组互相转换，其他类型如对象可以使用 __toString() 协议转为字符串，整数和浮点型也可以转为字符串
-                    or ($this->getVarType($var) === self::TYPE_STR and $type === self::TYPE_ARRAY)
-                    or ($this->getVarType($var) === self::TYPE_ARRAY and $type === self::TYPE_STR)
-                    // 禁止对象转为数组
-                    or ($this->getVarType($var) === self::TYPE_ARRAY and $type === self::TYPE_OBJECT)
-                ) {
-                    $this->fatalError($left, "Cannot re-assign variable `\${$var}` from " . $this->getVarType($var) . ' to ' . $type);
+                } else {
+                    $this->checkVarAssignExpr($left, $this->getVarType($var), $type);
                 }
             }
         } elseif ($this->isPropertyFetch($left) and !$left->getAttribute('nativeProperty')) {
@@ -3411,6 +3405,8 @@ class CompilerBase extends \PhpAot\Core\Translator
             return $this->convertToRef($arg->value);
         }
 
+        $this->checkVarAssignExpr($arg, $argInfo->type, $type);
+
         if ($argInfo->type === self::TYPE_OBJECT) {
             if ($this->isVarExpr($arg->value)) {
                 $object = $this->parseVariable($arg->value);
@@ -4730,6 +4726,37 @@ class CompilerBase extends \PhpAot\Core\Translator
         }
     }
 
+    protected function checkVarAssignExpr(NodeAbstract $left, string $toType, string $fromType): bool
+    {
+        if ($toType === self::TYPE_VAR or $fromType === self::TYPE_VAR) {
+            return true;
+        }
+        // 引用当前没有类型信息，按照 var 处理
+        if ($toType === self::TYPE_REF or $fromType === self::TYPE_REF) {
+            return true;
+        }
+        if ($toType === self::TYPE_OBJECT and $fromType === self::TYPE_OBJECT) {
+            return true;
+        }
+        if ($toType === self::TYPE_ARRAY and $fromType === self::TYPE_ARRAY) {
+            return true;
+        }
+        if ($toType === self::TYPE_STR) {
+            if ($fromType === self::TYPE_STR) {
+                return true;
+            }
+            if (!$this->strictTypes) {
+                $this->warning($left, "Attempt to implicitly convert `$fromType` to `$toType`");
+                return true;
+            }
+        }
+        // 原生类型可以互相转换，由 C++ 底层完成
+        if ($this->isNativeType($toType) and $this->isNativeType($fromType)) {
+            return true;
+        }
+        $this->fatalError($left, "Cannot re-assign variable from `$fromType` to `$toType`");
+    }
+
     protected function mustNoCall(NodeAbstract $node): void
     {
         $nodeFinder = new NodeFinder();
diff --git a/src/Php/MagicMethodDetector.php b/src/Php/MagicMethodDetector.php
index a038a45d..0d32ea02 100644
--- a/src/Php/MagicMethodDetector.php
+++ b/src/Php/MagicMethodDetector.php
@@ -32,7 +32,7 @@ trait MagicMethodDetector
                 $this->fatalError($v, 'Method ' . $this->class . "::{$name}() must take exactly 1 argument");
             }
         } elseif ($nameLower == '__tostring') {
-            if (!$this->checkArgType($returnType, self::TYPE_STR)) {
+            if (!$this->checkArgType($returnType, self::TYPE_STR, false)) {
                 $this->fatalError($v, 'Method ' . $this->class . "::{$name}() must return string");
             }
         } elseif ($nameLower == '__serialize') {
diff --git a/src/Php/Translator.php b/src/Php/Translator.php
index c2dc9a2d..2721399c 100644
--- a/src/Php/Translator.php
+++ b/src/Php/Translator.php
@@ -225,6 +225,11 @@ class Translator extends Preprocessor
             $this->error("The `libphpx.so` is not found, please run `make` to build it");
         }
 
+        $clangFormatVersion = shell_exec('clang-format --version');
+        if (empty($clangFormatVersion)) {
+            $this->formatCode = false;
+        }
+
         $files = $this->getFiles($path);
         // 应用 ignorePaths 过滤
         if (!empty($this->ignorePaths)) {