Add test for using first-class callable syntax inside annotations

See https://wiki.php.net/rfc/fcc_in_const_expr#examples

Author: thekid

src/test/php/lang/ast/unittest/emit/CallableSyntaxTest.class.php

@@ -6,6 +6,7 @@
 /**
  * Tests for first-class callable syntax
  *
+ * @see   https://wiki.php.net/rfc/fcc_in_const_expr
  * @see   https://wiki.php.net/rfc/first_class_callable_syntax#proposal
  */
 class CallableSyntaxTest extends EmittingTest {
@@ -182,4 +183,16 @@ public function __construct($value) { $this->value= $value; }
     }');
     Assert::equals($this, $f($this)->value);
   }
+
+  #[Test]
+  public function inside_annotation() {
+    $f= $this->run('use lang\Reflection; class %T {
+
+      #[Attr(strrev(...))]
+      public function run() {
+        return Reflection::of($this)->method("run")->annotation(Attr::class)->argument(0);
+      }
+    }');
+    Assert::equals('cba', $f('abc'));
+  }
 }