Cover the preg_replace_callback arrow-function reproducer in ArrowFunctionReturnTypeRuleTest

The second playground link on phpstan/phpstan#14914 uses an arrow function
without an explicit return type as the preg_replace_callback callback. That
case goes through ArrowFunctionReturnTypeRule (not ClosureReturnTypeRule), so
add it to bug-14914.php and assert no error there. Without the
replaceInFunctionCallStackParameterType fix it reports
"Anonymous function should return 'aa' but returns 'aa'|'possible?'".

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: 2 people

tests/PHPStan/Rules/Functions/ArrowFunctionReturnTypeRuleTest.php

@@ -77,4 +77,9 @@ public function testBugFunctionMethodConstants(): void
 		$this->analyse([__DIR__ . '/data/bug-anonymous-function-method-constant.php'], []);
 	}
 
+	public function testBug14914(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-14914.php'], []);
+	}
+
 }

tests/PHPStan/Rules/Functions/data/bug-14914.php

@@ -18,3 +18,13 @@ function (array $match): string {
 		flags: PREG_UNMATCHED_AS_NULL,
 	);
 }
+
+function doBar(): void
+{
+	preg_replace_callback(
+		'/a|(?<b>b)/',
+		fn (array $match) => $match['b'] !== null ? 'aa' : 'possible?',
+		'abcd',
+		flags: PREG_UNMATCHED_AS_NULL,
+	);
+}