PHP Parse error in DatabaseInterface.php after updating from 4.9.7 to 4.9.8

[aartsr]

Describe the bug

All previous phpmyadmin versions in the 4.9-branch have given no problems on this setup (I've simply reverted back to 4.9.7 for now). Using version 4.9.8 however throws this error: PHP Parse error: syntax error, unexpected '?' in ../phpmyadmin/libraries/classes/DatabaseInterface.php on line 1566. The line in question is $storageDbName = $GLOBALS['cfg']['Server']['pmadb'] ?? '';

Server configuration

Operating system: Debian Jessie
Web server: apache/2.4.10
Database version: MySQL 5.5.62
PHP version: 5.6.40
phpMyAdmin version: 4.9.8

Client configuration

Browsers: Firefox/Chrome/Edge
Operating system: Windows 10

Additional context

/**
* This function checks and initialises the phpMyAdmin configuration
* storage state before it is used into session cache.
*
* @return void
*/
public function initRelationParamsCache()
{
$storageDbName = $GLOBALS['cfg']['Server']['pmadb'] ?? '';
// Use "phpmyadmin" as a default database name to check to keep the behavior consistent
$storageDbName = $storageDbName !== null
&& is_string($storageDbName)
&& $storageDbName !== '' ? $storageDbName : 'phpmyadmin';

    // This will make users not having explicitly listed databases
    // have config values filled by the default phpMyAdmin storage table name values
    $this->relation->fixPmaTables($storageDbName, false);

    // This global will be changed if fixPmaTables did find one valid table
    $storageDbName = $GLOBALS['cfg']['Server']['pmadb'] ?? '';

    // Empty means that until now no pmadb was found eligible
    if (empty($storageDbName)) {
        $this->relation->fixPmaTables($GLOBALS['db'], false);
    }
}

[MauricioFauth]

Hi @aartsr.
Thank you for reporting this issue. This is a mistake that was introduced when we back-ported a fix into the 4.9.x branch.
As an immediate fix, you can change these lines to:

diff --git a/libraries/classes/DatabaseInterface.php b/libraries/classes/DatabaseInterface.php
index 7ab5d754fb..0edc297cd3 100644
--- a/libraries/classes/DatabaseInterface.php
+++ b/libraries/classes/DatabaseInterface.php
@@ -1563,7 +1563,7 @@ class DatabaseInterface
      */
     public function initRelationParamsCache()
     {
-        $storageDbName = $GLOBALS['cfg']['Server']['pmadb'] ?? '';
+        $storageDbName = isset($GLOBALS['cfg']['Server']['pmadb']) ? $GLOBALS['cfg']['Server']['pmadb'] : '';
         // Use "phpmyadmin" as a default database name to check to keep the behavior consistent
         $storageDbName = $storageDbName !== null
                             && is_string($storageDbName)
@@ -1574,7 +1574,7 @@ class DatabaseInterface
         $this->relation->fixPmaTables($storageDbName, false);
 
         // This global will be changed if fixPmaTables did find one valid table
-        $storageDbName = $GLOBALS['cfg']['Server']['pmadb'] ?? '';
+        $storageDbName = isset($GLOBALS['cfg']['Server']['pmadb']) ? $GLOBALS['cfg']['Server']['pmadb'] : '';
 
         // Empty means that until now no pmadb was found eligible
         if (empty($storageDbName)) {

[aartsr]

Thanx for the quick reply/fix.