Change license back to GPL 2

[georgringer]

Since https://github.com/TYPO3-Solr/ext-solr/pull/1792 it is GPL3 but as core is GPL2 IMHO & IANAL the extension must be GPL 2 as well!

[dkd-kaehm]

@georgringer See:

• https://github.com/TYPO3-Solr/ext-solr/pull/1792#issuecomment-2687249510
• https://github.com/TYPO3-Solr/ext-solr/pull/1792#issuecomment-2687250930

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Infos:

We want to look at it closely.

TYPO3 guidelines speaks about "GPLv2 or any later version"

TYPO3 guidelines for Extensions says:

TYPO3 is released under the terms of GNU General Public License version 2 or any later version. The copyright notice with a reference to the license text must be included at the top of every TYPO3 PHP class file. User files must have this copyright notice as well. Example:

<?php
declare(strict_types = 1);

/*
 * This file is part of the TYPO3 CMS project.
 *
 * It is free software; you can redistribute it and/or modify it under
 * the terms of the GNU General Public License, either version 2
 * of the License, or any later version.
 *
 * For the full copyright and license information, please read the
 * LICENSE.txt file that was distributed with this source code.
 *
 * The TYPO3 project - inspiring people to share!
 */

 namespace Vendor\SomeExtension\SomeFolder;

Help wanted.

If somebody has a 100% legal declaration and proof against using GPLv3 and/or for GPLv2, please leave the comments or contact us.

QA:

License Compatibility to TYPO3

• [x] Can a TYPO3 extension use the GPLv3? Most probably YES, See: https://typo3.org/project/licenses

  TYPO3 CMS 3.x and higher is licensed under the GNU General Public License, version 2 or later.

  • [x] Doesn't matter, because of "2 or later" ~If "it depends": Can EXT:solr and its add-ons use GPLv3?~

License Compatibility to Apache Solr

• [x] Must EXT:solr be compatible with Apache Solr license? Most probably yes, because EXT:solr uses and distributes the Apache Solr TYPO3 plugin, which is licensed as Apache License 2.0
• [x] Is GPLv3 compatible with Apache License 2.0? YES, see: https://www.gnu.org/licenses/license-list.html#apache2 Or https://en.wikipedia.org/wiki/GNU_General_Public_License#Compatibility_and_multi-licensing

  The fourth and final discussion draft[32] was released on 31 May 2007. It introduced Apache License version 2.0 compatibility (prior versions are incompatible)

[dkd-kaehm]

IMHO we can and must leave the GPLv3 as is. See my previous comment.