From 43054d1c9650eb469f8d58274eb67fa169789a22 Mon Sep 17 00:00:00 2001
From: IanM <ian@morland.me>
Date: Wed, 5 Aug 2026 10:11:41 +0100
Subject: [PATCH] Fix 'using null as an array offset is deprecated' on PHP 8.5

In Line::concat() the two guards test the array before testing the index:

    if ((isset($mSources[$fi])) && ($fi !== null)) {

`isset($mSources[$fi])` evaluates the offset first, so `$fi !== null` is
never reached with $fi null and the null check is unreachable. $fi and $ni
are null whenever a position has no source file or no name, which is
routine, and PHP 8.5 reports each occurrence.

Swapping the operands cannot change behaviour, since isset() on a null
offset is already false. Verified on 8.5: concat() output is byte-identical
before and after, and the test suite passes on 8.1 through 8.5.
---
 src/parsing/Line.php | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/parsing/Line.php b/src/parsing/Line.php
index 135441c..1ac4468 100644
--- a/src/parsing/Line.php
+++ b/src/parsing/Line.php
@@ -489,10 +489,10 @@ public function concat($line, $dColumn, $mSources, $mNames)
             $generated->column += $dColumn;
             $fi = $source->fileIndex;
             $ni = $source->nameIndex;
-            if ((isset($mSources[$fi])) && ($fi !== null)) {
+            if (($fi !== null) && (isset($mSources[$fi]))) {
                 $source->fileIndex = $mSources[$fi];
             }
-            if ((isset($mNames[$ni])) && ($ni !== null)) {
+            if (($ni !== null) && (isset($mNames[$ni]))) {
                 $source->nameIndex = $mNames[$ni];
             }
             $npos[$generated->column] = $position;