From f42bbc2403ebc1178d9ae4f1029c0e8ddc6aa451 Mon Sep 17 00:00:00 2001
From: Nikita Popov <nikita.ppv@googlemail.com>
Date: Fri, 30 Nov 2018 11:00:48 +0100
Subject: [PATCH] Avoid default action for error production

error is not necessarily going to have a semantic value, make sure
that the default action $$=$1 is not used.

Fixes #551.
---
 grammar/php7.y                               | 1 +
 lib/PhpParser/Parser/Php7.php                | 2 +-
 test/code/parser/errorHandling/recovery.test | 8 +++++++-
 3 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/grammar/php7.y b/grammar/php7.y
index 7705113..681fda0 100644
--- a/grammar/php7.y
+++ b/grammar/php7.y
@@ -959,6 +959,7 @@ array_pair_list:
 comma_or_error:
       ','
     | error
+          { /* do nothing -- prevent default action of $$=$1. See #551. */ }
 ;
 
 inner_array_pair_list:
diff --git a/lib/PhpParser/Parser/Php7.php b/lib/PhpParser/Parser/Php7.php
index a28a2c4..b34ee82 100644
--- a/lib/PhpParser/Parser/Php7.php
+++ b/lib/PhpParser/Parser/Php7.php
@@ -2361,7 +2361,7 @@ class Php7 extends \PhpParser\ParserAbstract
                 $this->semValue = $this->semStack[$stackPos];
             },
             498 => function ($stackPos) {
-                $this->semValue = $this->semStack[$stackPos];
+                 /* do nothing -- prevent default action of $$=$this->semStack[$1]. See $551. */
             },
             499 => function ($stackPos) {
                  $this->semStack[$stackPos-(3-1)][] = $this->semStack[$stackPos-(3-3)]; $this->semValue = $this->semStack[$stackPos-(3-1)];
diff --git a/test/code/parser/errorHandling/recovery.test b/test/code/parser/errorHandling/recovery.test
index ae3518d..fdb5ed2 100644
--- a/test/code/parser/errorHandling/recovery.test
+++ b/test/code/parser/errorHandling/recovery.test
@@ -1400,4 +1400,10 @@ array(
             )
         )
     )
-)
\ No newline at end of file
+)
+-----
+<?php
+$a = ["a "thing"];
+-----
+!!php7
+Syntax error, unexpected T_STRING, expecting ',' or ')' or ']' from 2:11 to 2:15
\ No newline at end of file