Added regression test

Author: staabm

tests/PHPStan/Rules/Pure/PureFunctionRuleTest.php

@@ -204,4 +204,9 @@ public function testBug13201(): void
 		$this->analyse([__DIR__ . '/data/bug-13201.php'], []);
 	}
 
+	public function testBug12119(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-12119.php'], []);
+	}
+
 }

tests/PHPStan/Rules/Pure/data/bug-12119.php

@@ -0,0 +1,21 @@
+<?php
+
+namespace Bug12119;
+
+/** @phpstan-pure */
+function testFunction(string $s): string { return ''; }
+
+class HelloWorld
+{
+	/** @phpstan-pure */
+	public function testMethod(string $s): string { return ''; }
+
+	/** @phpstan-pure */
+	public function sayHello(string $s): string
+	{
+		$a = $this->testMethod('random_int');
+		$b = testFunction('random_int');
+
+		return $a . $b;
+	}
+}