Deprecate passing $ifexpr to ForNode

phpstan-baseline.neon

@@ -6,12 +6,6 @@ parameters:
 			count: 1
 			path: src/Extension/CoreExtension.php
 
-		- # Avoid BC-break
-			message: '#^Constructor of class Twig\\Node\\ForNode has an unused parameter \$ifexpr\.$#'
-			identifier: constructor.unusedParameter
-			count: 1
-			path: src/Node/ForNode.php
-
 		- # 2 parameters will be required
 			message: '#^Method Twig\\Node\\IncludeNode\:\:addGetTemplate\(\) invoked with 2 parameters, 1 required\.$#'
 			identifier: arguments.count

src/Node/ForNode.php

@@ -31,6 +31,10 @@ class ForNode extends Node
     {
         $body = new Nodes([$body, $this->loop = new ForLoopNode($lineno)]);
 
+        if (null !== $ifexpr) {
+            trigger_deprecation('twig/twig', '3.19', \sprintf('Passing not-null to the "ifexpr" argument of the "%s" constructor is deprecated.', static::class));
+        }
+
         $nodes = ['key_target' => $keyTarget, 'value_target' => $valueTarget, 'seq' => $seq, 'body' => $body];
         if (null !== $else) {
             $nodes['else'] = $else;