refactor(compiler): 优化关键字方法分派逻辑

- 简化了关键字方法和扩展方法的检测流程
- 统一了接收器类型的获取方式
- 提取了重复的空值检查逻辑
- 改进了代码结构和可读性
- 为关键字扩展方法添加了测试用例

src/Php/CompilerBase.php

@@ -5444,34 +5444,23 @@ class CompilerBase extends \PhpAot\Core\Translator
         $magicMethod = false;
         $method = $this->identifierToStr($expr->name, literal: true);
 
-        // to* conversion methods are language keywords — always dispatched directly
+        // keyword methods (to* builtins + __ extensions) — dispatched before type-specific logic
         if ($this->isNamedMethod($expr->name)) {
             $methodName = $expr->name->toString();
-            if (isset(self::KEYWORD_METHOD_MAP[$methodName])) {
-                if ($this->isVarExpr($expr->var)) {
-                    $receiverType = $this->getVarType($object);
-                } else {
-                    $receiverType = $this->detectTypeOfExpr($expr->var);
-                }
+            $receiverType = $this->isVarExpr($expr->var) ? $this->getVarType($object) : $this->detectTypeOfExpr($expr->var);
             if ($receiverType === self::TYPE_VOID) {
                 $this->fatalError($expr->var, 'Cannot call method on void');
             }
+            // to* builtins
+            if (isset(self::KEYWORD_METHOD_MAP[$methodName])) {
                 if ($methodName === 'toObject') {
                     return $this->genToObjectCall($expr, $object);
                 }
                 return $this->genToConvertCall($object, $methodName, $receiverType);
             }
-            // keyword extension methods (__ functions) — dispatched before type-specific logic
+            // __ keyword extensions
             $kwExt = $this->findKeywordExtensionMethod($methodName);
             if ($kwExt) {
-                if ($this->isVarExpr($expr->var)) {
-                    $receiverType = $this->getVarType($object);
-                } else {
-                    $receiverType = $this->detectTypeOfExpr($expr->var);
-                }
-                if ($receiverType === self::TYPE_VOID) {
-                    $this->fatalError($expr->var, 'Cannot call method on void');
-                }
                 return $this->parseUniversalMethodCall($expr, $object, $methodName, $kwExt, $this->isVarExpr($expr->var));
             }
         }

tests/aot/keyword_extension/001.phpt

@@ -0,0 +1,26 @@
+--TEST--
+keyword extension method: varDump()
+--FILE--
+<?php
+declare(strict_types=1);
+use native_types;
+
+function __var_dump(mixed $var): void {
+    var_dump($var);
+}
+
+function main(): void {
+    $str = "hello world";
+    $str->varDump();
+
+    $int_val = 42;
+    $int_val->varDump();
+
+    $float_val = 3.14;
+    $float_val->varDump();
+}
+?>
+--EXPECT--
+string(11) "hello world"
+int(42)
+float(3.14)