Description

The following code:

<?php
$ldap_server = 'ldap://localhost';
$root_dn = 'ou=people,dc=example,dc=com';

$ldap = ldap_connect( $ldap_server );
ldap_set_option($ldap, LDAP_OPT_PROTOCOL_VERSION, 3);
ldap_bind($ldap); // Anonymous bind

// Creating an array with a hole in it
$attr = array_unique(['cn', 'uid', 'uid', 'mail']);
$res = ldap_search($ldap, $root_dn, 'uid=admin', $attr);
echo ldap_error($ldap);

Resulted in this output:

Warning: ldap_search(): Array initialization wrong in ./test.php on line 11

Call Stack:
    0.0012     401536   1. {main}() ./test.php:0
    0.1191     401816   2. ldap_search($ldap = class LDAP\Connection {  }, $base = 'ou=people,dc=example,dc=com', $filter = 'uid=admin', $attributes = [0 => 'cn', 1 => 'uid', 3 => 'mail']) ./test.php:11

Success  

But I expected this output instead:

Success

If $attr has no holes in the keys (i.e. remove array_unique() or call array_values()) then it works fine.

Maybe this is normal, but in that case I believe the documentation should clarify that, as it currently does not say anything about $attributes parameter needing to be a list with keys in a strict sequence.

PHP Version

8.2.27, 8.4.2

Operating System

MacOS 14.6.1