Added regression test

Author: staabm

tests/PHPStan/Rules/Variables/ParameterOutAssignedTypeRuleTest.php

@@ -64,4 +64,9 @@ public function testBenevolentArrayKey(): void
 		$this->analyse([__DIR__ . '/data/benevolent-array-key.php'], []);
 	}
 
+	public function testBug12754(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-12754.php'], []);
+	}
+
 }

tests/PHPStan/Rules/Variables/data/bug-12754.php

@@ -0,0 +1,26 @@
+<?php
+
+namespace Bug12754;
+
+class HelloWorld
+{
+	/**
+	 * @param list<array{string, string}> $list
+	 * @return void
+	 */
+	public function modify(array &$list): void
+	{
+		foreach ($list as $int => $array) {
+			$list[$int][1] = $this->apply($array[1]);
+		}
+	}
+
+	/**
+	 * @param string $value
+	 * @return string
+	 */
+	public function apply(string $value): mixed
+	{
+		return $value;
+	}
+}