fix: reject unsupported Decimal round modes

phpunit/code/round-decimal-native-path.php

@@ -0,0 +1,14 @@
+<?php
+/**
+ * This file is part of TypePHP(AOT).
+ *
+ * @link     https://www.swoole.com/aot/
+ * @contact  service@swoole.com
+ */
+
+function main(): void
+{
+    $decimal = std::decimal('2.567');
+    $whole = round($decimal);
+    $precise = round($decimal, 2);
+}

phpunit/src/NegativeCompatibilityTest.php

@@ -145,6 +145,30 @@ function main(): void
 PHP,
         ];
 
+        yield 'Decimal round mode' => [
+            'convert',
+            'round() with Decimal supports at most 2 arguments',
+            <<<'PHP'
+<?php
+function main(): void
+{
+    round(std::decimal('2.5'), 0, PHP_ROUND_HALF_DOWN); // @diagnostic
+}
+PHP,
+        ];
+
+        yield 'round excessive arguments with Decimal' => [
+            'convert',
+            'round() expects at most 3 argument(s), 4 given',
+            <<<'PHP'
+<?php
+function main(): void
+{
+    round(std::decimal('2.5'), 0, PHP_ROUND_HALF_DOWN, 4); // @diagnostic
+}
+PHP,
+        ];
+
         yield 'break level exceeds enclosing depth' => [
             'convert',
             "Cannot 'break' 2 levels",

phpunit/src/RoundModeTest.php

@@ -56,6 +56,13 @@ class RoundModeTest extends TestCase
         self::assertSame(2, substr_count($cpp, 'php::fn::round('));
     }
 
+    public function testDecimalCallsWithoutAModeKeepTheDecimalFastPath(): void
+    {
+        $cpp = $this->compileToCpp('round-decimal-native-path.php');
+
+        self::assertSame(2, substr_count($cpp, 'php::Decimal::round('));
+    }
+
     private function compileToCpp(string $file): string
     {
         global $translator;

src/Optimizer/FuncCallOptimizer.php

@@ -1015,6 +1015,13 @@ trait FuncCallOptimizer
         }
         $type = $this->detectTypeOfExpr($e->args[0]->value);
         if ($type === Type::DECIMAL) {
+            // Decimal is a PHPX Box resource at the Zend boundary, so the
+            // generic round() function cannot implement its rounding mode.
+            // Reject the unsupported extension form instead of silently
+            // dropping the explicit argument or producing a resource TypeError.
+            if (count($e->args) > 2) {
+                $this->fatalError($e, 'round() with Decimal supports at most 2 arguments');
+            }
             $a0 = $this->parseExpr($e->args[0]->value);
             if (count($e->args) >= 2) {
                 return 'php::Decimal::round(' . $a0 . ', ' . $this->parseExpr($e->args[1]->value) . ')';