Add rule test for get_parent_class($this) === self::class not being always false

Covers the reported identical.alwaysFalse false positive at the rule level, in
addition to the type-inference assertions.

Author: zonuexe

tests/PHPStan/Rules/Comparison/StrictComparisonOfDifferentTypesRuleTest.php

@@ -347,6 +347,11 @@ public function testBug2835(): void
 		$this->analyse([__DIR__ . '/data/bug-2835.php'], []);
 	}
 
+	public function testBug14951(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-14951.php'], []);
+	}
+
 	public function testBug1860(): void
 	{
 		$this->analyse([__DIR__ . '/data/bug-1860.php'], [

tests/PHPStan/Rules/Comparison/data/bug-14951.php

@@ -0,0 +1,23 @@
+<?php declare(strict_types = 1);
+
+namespace Bug14951StrictComparison;
+
+class A
+{
+
+	public function isDirectChildOfA(): bool
+	{
+		// $this can be an instance of a subclass, so get_parent_class($this)
+		// can equal self::class for a direct child — this comparison is not always false.
+		return get_parent_class($this) === self::class;
+	}
+
+}
+
+class B extends A
+{
+}
+
+class C extends B
+{
+}