Cover get_parent_class(self::class) inside a trait

self::class is not late static bound: inside a trait it is already the using class as a
constant class-string, indistinguishable from writing Bar::class, so it keeps the exact
parent while $this / static::class stay conservative.

Author: zonuexe

tests/PHPStan/Analyser/nsrt/get-parent-class.php

@@ -49,6 +49,12 @@ public function doBaz()
 		assertType('class-string|false', get_parent_class());
 		assertType('class-string|false', get_parent_class($this));
 		assertType('class-string|false', get_parent_class(static::class));
+
+		// self::class is not late static bound - it is the using class, so it is already a
+		// constant class-string here, indistinguishable from writing Bar::class.
+		assertType('\'ParentClass\\\\Bar\'', self::class);
+		assertType('\'ParentClass\\\\Foo\'', get_parent_class(self::class));
+		assertType('\'ParentClass\\\\Foo\'', get_parent_class(Bar::class));
 	}
 
 }