Optionally used in Qt GUI. Configure with -system-harfbuzz to force the use of the system library, or -no-harfbuzz to disable the use of HarfBuzz entirely.
The sources can be found in qt-everywhere-src-5.15.2/qtbase/src/3rdparty/harfbuzz.
Copyright © 2008,2010 Nokia Corporation and/or its subsidiary(-ies) Copyright © 2006 Behdad Esfahbod Copyright © 2005 David Turner Copyright © 2004,2007,2008,2009,2010 Red Hat, Inc. Copyright © 1998-2004 David Turner and Werner Lemberg
HarfBuzz was previously licensed under different licenses. This was changed in January 2008. If you need to relicense your old copies, consult the announcement of the license change on the internet. Other than that, each copy of HarfBuzz is licensed under the COPYING file included with it. The actual license follows: Permission is hereby granted, without written agreement and without license or royalty fees, to use, copy, modify, and distribute this software and its documentation for any purpose, provided that the above copyright notice and the following two paragraphs appear in all copies of this software. IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.