From b81818b287db0196d623dcba5b36488c6122a64f Mon Sep 17 00:00:00 2001
From: epriestley <git@epriestley.com>
Date: Sun, 26 Apr 2020 08:30:30 -0700
Subject: [PATCH] Accommodate PHP 7.4 changes to certain "preg_match_all()"
 calls

Summary:
Ref T13518. The result format of this call changed in PHP 7.4, which causes us to emit "-1" matches because "-1" survives `array_filter()`.

Filter results in a way that should survive both result formats.

Test Plan: Ran `arc unit --everything` under PHP 7.4.

Maniphest Tasks: T13518

Differential Revision: https://secure.phabricator.com/D21173
---
 src/parser/xhpast/api/XHPASTNode.php | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/src/parser/xhpast/api/XHPASTNode.php b/src/parser/xhpast/api/XHPASTNode.php
index 0f0f9911..4decaea1 100644
--- a/src/parser/xhpast/api/XHPASTNode.php
+++ b/src/parser/xhpast/api/XHPASTNode.php
@@ -163,7 +163,26 @@ final class XHPASTNode extends AASTNode {
     $re = '/\\\\.|(\$|\{\$|\${)([a-z_\x7F-\xFF][a-z0-9_\x7F-\xFF]*)/i';
     $matches = null;
     preg_match_all($re, $value, $matches, PREG_OFFSET_CAPTURE);
-    return ipull(array_filter($matches[2]), 0, 1);
+
+    // NOTE: The result format for this construction changed in PHP 7.4.
+    // See T13518.
+
+    $names = $matches[2];
+    foreach ($names as $name_idx => $name_match) {
+      if ($name_match === '') {
+        unset($names[$name_idx]);
+        continue;
+      }
+
+      if ($name_match[1] === -1) {
+        unset($names[$name_idx]);
+        continue;
+      }
+    }
+
+    $names = ipull($names, 0, 1);
+
+    return $names;
   }
 
   public function getStringLiteralValue() {