Added regression test

Author: staabm

tests/PHPStan/Rules/Comparison/ImpossibleCheckTypeFunctionCallRuleTest.php

@@ -1038,4 +1038,10 @@ public function testBug6788(): void
 		$this->analyse([__DIR__ . '/data/bug-6788.php'], []);
 	}
 
+	public function testBug13268(): void
+	{
+		$this->treatPhpDocTypesAsCertain = true;
+		$this->analyse([__DIR__ . '/data/bug-13268.php'], []);
+	}
+
 }

tests/PHPStan/Rules/Comparison/data/bug-13268.php

@@ -0,0 +1,28 @@
+<?php declare(strict_types = 1);
+
+namespace Bug13268;
+
+class HelloWorld
+{
+	public function assignInCall(string $string): ?string
+	{
+		if (
+			is_string(
+				$string = realpath($string)
+			)
+		) {
+			throw new \RuntimeException('Refusing to overwrite existing file: ' . $string);
+		}
+		return null;
+	}
+
+	public function dumpToLog(mixed $dumpToLog): ?string
+	{
+		if (is_string($dumpToLog)) {
+			if (file_exists($dumpToLog) || is_string($dumpToLog = realpath($dumpToLog))) {
+				throw new \RuntimeException('Refusing to overwrite existing file: ' . $dumpToLog);
+			}
+		}
+		return null;
+	}
+}