Bug Report

We ran into this while moving a mid-sized PHP 8.5 codebase to typed signatures. No test or static check noticed it; a byte-for-byte comparison of every rendered page before and after the Rector run did, because a label silently disappeared.

Minimal PHP Code Causing Issue

https://getrector.com/demo/ddc74e4e-f838-4b17-9335-cca401864bd9

<?php
function g($a, $b) { return ($a !== null) ? $a : ($b ? 'yes' : 'no'); }
function h($a, $b) { return null === $a ? ($b ? 'yes' : 'no') : $a; }
function m($a, $b) { return isset($a) ? $a : ($b ? 'yes' : 'no'); } // control: already fixed via #9649

Config: RectorConfig::configure()->withRules([TernaryToNullCoalescingRector::class]);

Actual diff:

-function g($a, $b) { return ($a !== null) ? $a : ($b ? 'yes' : 'no'); }
-function h($a, $b) { return null === $a ? ($b ? 'yes' : 'no') : $a; }
+function g($a, $b) { return $a ?? $b ? 'yes' : 'no'; }
+function h($a, $b) { return $a ?? $b ? 'yes' : 'no'; }
-function m($a, $b) { return isset($a) ? $a : ($b ? 'yes' : 'no'); }
+function m($a, $b) { return $a ?? ($b ? 'yes' : 'no'); }

?? binds tighter than ?:, so the result parses as ($a ?? $b) ? 'yes' : 'no'. For $a = 'abc', $b = false the original returns 'abc', the rewritten code returns 'yes'.

Expected Behaviour

return $a ?? ($b ? 'yes' : 'no'); — as the isset() / is_null() branches already do since rector-src #7889, #7916 and #7969 (issues #9649, #9674).

Cause

In refactor(), the Identical / NotIdentical path calls createCoalesce($checkedNode, $fallbackNode) without preserveWrappedFallback($fallbackNode). The underlying cause is nikic/PHP-Parser#1119: the format-preserving printer does not re-add parentheses for an unchanged node moved under a new parent. A nested ternary fallback is always parenthesized in valid PHP 8 code, so every such case is affected.

Suggested fix: call $this->preserveWrappedFallback($fallbackNode) on that path as well, with a fixture (e.g. keep_right_parentheses_not_identical.php.inc) covering both !== null and === null. Happy to send a PR if that direction is welcome.