Added regression test

Author: staabm

tests/PHPStan/Rules/Comparison/MatchExpressionRuleTest.php

@@ -552,4 +552,13 @@ public function testBug11246(): void
 		$this->analyse([__DIR__ . '/data/bug-11246.php'], []);
 	}
 
+	public function testBug9879(): void
+	{
+		if (PHP_VERSION_ID < 80100) {
+			$this->markTestSkipped('Test requires PHP 8.1.');
+		}
+
+		$this->analyse([__DIR__ . '/data/bug-9879.php'], []);
+	}
+
 }

tests/PHPStan/Rules/Comparison/data/bug-9879.php

@@ -0,0 +1,18 @@
+<?php declare(strict_types = 1); // lint >= 8.1
+
+namespace Bug9879;
+
+final class A {
+	public function test(): void
+	{
+		for($idx = 0; $idx < 6; $idx += 1) {
+			match($idx % 3) {
+				0 => 1,
+				1 => 2,
+				2 => 0,
+			};
+		}
+
+	}
+
+}