From 495e377d5b6c66e9783d1f7202e7def155ec482d Mon Sep 17 00:00:00 2001
From: jblairy <julien@blairy.fr>
Date: Fri, 28 Aug 2026 14:37:59 +0200
Subject: [PATCH] [CodingStyle] Skip callee arity mismatch on
 ArrowFunctionDelegatingCallToFirstClassCallableRector
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Fixes a silent behavior change: the rule converts a 0-arity arrow function
delegating to a method with an unused optional parameter into a first-class
callable, which then forwards any extra argument the produced callable is
invoked with — the original arrow function silently ignored it.
---
 ...zero_arity_optional_param_on_callee.php.inc | 18 ++++++++++++++++++
 ...nctionAndClosureFirstClassCallableGuard.php |  2 +-
 2 files changed, 19 insertions(+), 1 deletion(-)
 create mode 100644 rules-tests/CodingStyle/Rector/ArrowFunction/ArrowFunctionDelegatingCallToFirstClassCallableRector/Fixture/skip_zero_arity_optional_param_on_callee.php.inc

diff --git a/rules-tests/CodingStyle/Rector/ArrowFunction/ArrowFunctionDelegatingCallToFirstClassCallableRector/Fixture/skip_zero_arity_optional_param_on_callee.php.inc b/rules-tests/CodingStyle/Rector/ArrowFunction/ArrowFunctionDelegatingCallToFirstClassCallableRector/Fixture/skip_zero_arity_optional_param_on_callee.php.inc
new file mode 100644
index 00000000000..5ea6ad6c332
--- /dev/null
+++ b/rules-tests/CodingStyle/Rector/ArrowFunction/ArrowFunctionDelegatingCallToFirstClassCallableRector/Fixture/skip_zero_arity_optional_param_on_callee.php.inc
@@ -0,0 +1,18 @@
+<?php
+
+namespace Rector\Tests\CodingStyle\Rector\ArrowFunction\ArrowFunctionDelegatingCallToFirstClassCallableRector\Fixture;
+
+use Rector\Tests\CodingStyle\Rector\ArrowFunction\ArrowFunctionDelegatingCallToFirstClassCallableRector\Source\FooBar;
+
+final class SkipZeroArityOptionalParamOnCallee
+{
+    public function run(?\Closure $callback = null)
+    {
+        return $this->apply($callback ?? fn () => FooBar::optionalArgs());
+    }
+
+    private function apply(callable $callback)
+    {
+        return $callback('not optional-args input');
+    }
+}
diff --git a/rules/CodingStyle/Guard/ArrowFunctionAndClosureFirstClassCallableGuard.php b/rules/CodingStyle/Guard/ArrowFunctionAndClosureFirstClassCallableGuard.php
index 9cea1b90e14..6c58fc97f4a 100644
--- a/rules/CodingStyle/Guard/ArrowFunctionAndClosureFirstClassCallableGuard.php
+++ b/rules/CodingStyle/Guard/ArrowFunctionAndClosureFirstClassCallableGuard.php
@@ -117,7 +117,7 @@ public function shouldSkip(
             return false;
         }
 
-        return count($parameters) > 1;
+        return count($parameters) !== count($args);
     }
 
     private function isBuiltinReflection(FunctionReflection|MethodReflection $reflection): bool