It's debateable whether or not this is necessary when minifying on-the-fly...
Copyright (C) YYYY Developer
redistribute it and/or modify it under the terms of the GNU
General Public License (GNU GPL) as published by the Free Software
Foundation, either version 3 of the License, or (at your option)
any later version. The code is distributed WITHOUT ANY WARRANTY;
without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU GPL for more details.
As additional permission under GNU GPL version 3 section 7, you
may distribute non-source (e.g., minimized or compacted) forms of
that code without the copy of the GNU GPL normally required by
section 4, provided you include this license notice and a URL
through which recipients can access the Corresponding Source.
From a license compatibility point of view, would it be ok to add this notice at the beginning of the merged file ?
I would leave the license headers at the beginning of each minified file because that's how it appears now with pre-minified files that are simply included (e.g., jquery.js and jquery-ui.js).
p.s. ignore comment:2.
I am not confident with 'updating JSMin.php' and vote for a wontfix. The important thing is that we take licenses seriously and any Piwik user is able to find out the licenses of the libraries we use by looking at the well maintained file: https://github.com/piwik/piwik/blob/master/LEGALNOTICE
Most Open Source projects don't have such a file, so this is already a great effort to make visible the libraries we use and their licenses.
A couple of points:
jsmin is deprecated, cf : https://github.com/rgrove/jsmin-php/ :
This project is unmaintained. I stopped using it years ago. You shouldn't use it. You shouldn't use any version of JSMin.
I found https://github.com/tedivm/JShrink as a replacement and will remove jsmin while fixing #4373.
JShrink preserves licenses.
In 6624e27: fixes #4373, #1640
In fbd4675: Refs #1640 Adding jshrink to LEGALNOTICE + update help text
fixes #4373, #1640
Refs #1640 Adding jshrink to LEGALNOTICE + update help text