Edward Welbourne d2473b30c4 Revise UCD-generated data files' SPDX headers
The existing data comes under Unicode-DFS-2016 but future updates
shall come under Unicode-3.0, so update the existing headers with the
former and the generator script with the latter. Leave a note in the
attribution file about this transitional state and how to resolve it.

Replaced UNICODE_LICENSE.txt from src/corelib/text/ with
LICENSES/Unicode-DFS-2016.txt, as fetched using reuse download.
This doesn't look like a rename but only actually adds some irrelevant
lines about where on the Unicode website the upstream files (to which
we do not apply this license) come from and changes some spacing.

Pick-to: 6.5
Fixes: QTBUG-121653
Change-Id: I50c9f4badc77a9aa402af946561aff58ae9e3e7a
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
Reviewed-by: Kai Köhne <kai.koehne@qt.io>
(cherry picked from commit d5e40b5e58c187086d7c23af1860c1af28957ccc)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
2024-04-22 15:22:23 +00:00
..
2022-10-11 14:10:59 +00:00
2022-05-16 16:37:38 +02:00
2022-05-16 16:37:38 +02:00

Unicode is used to generate the unicode data in src/corelib/text/.

To update:
* Run `./update_ucd.sh $Version`. This automates the following steps:
  * Find the data (UAX #44, UCD; not the XML version) at
    https://www.unicode.org/Public/zipped/$Version/
  * Unpack the zip file; for each file in data/, replace with the new
    version; find the *BreakProperty.txt in auxiliary/ and emoji-data.txt
    in emoji/.
  * In tst_QTextBoundaryFinder's data/ sub-directory, update its files
    from the auxiliary/ sub-directory of the UCD data.
  * Download https://www.unicode.org/Public/idna/$Version/IdnaMappingTable.txt
    and put it into data/.
  * Download https://www.unicode.org/Public/idna/$Version/IdnaTestV2.txt
    and put it into tests/auto/corelib/io/qurluts46/testdata.
* If needed, add an entry to enum QChar::UnicodeVersion for the new
  Unicode version
* In that case, also update main.cpp's initAgeMap and DATA_VERSION_S*
  to match
* Build this project. Its binary, unicode, ignores command-line
  options and assumes it is being run from this directory. When run,
  it produces lots of output. If it gets as far as updating
  qunicodetables.cpp the output hopefully doesn't matter.
* It'll end prematurely with a qFatal() message if it needs updates,
  either in main.cpp or in QChar:
  * "unassigned or unhandled age value:" initAgeMap() and
    QChar::UnicodeVersion;
  * "Unhandled script property value:" initScriptMap(), QChar::Script,
    qharfbuzzng.cpp's _qtscript_to_hbscript[] array and
    qfontconfigdatabase.cpp's specialLanguages.
  * "unassigned word break class:" enum WordBreakClass,
    word_break_class_string and initWordBreak();
* Assertions or other qFatal()s may trigger: if so, study code and
  understand what's more complicated about this update; talk to folk
  named in the git logs, maybe push a WIP to gerrit to solicit
  advice. Some bit-field may need to be expanded, for example. In some
  cases QChar may need additions to some of its enums.
* Build with the modified code, fix any compilation issues, make check
  in suitable directories, including tst_QTextBoundaryFinder.
* That may have updated qtbase/src/corelib/text/qunicodetables.cpp; if
  so the update matters; be sure to commit the changes to data/ at the
  same time and update text/qt_attribution.json to match; use the UCD
  Revision number, rather than the Unicode standard number, as the
  Version, for all that qunicodetables.cpp uses the latter (see the
  'UAX #44, UCD' page linked from https://www.unicode.org/ucd/ for the
  table with this).
* If there are enum additions in qchar.h (public API), be sure to also
  update the documentation in qchar.cpp for each affected enum,
  respecting the existing ordering.
* If you don't normally build in the source tree, remember to delete
  qtbase/.qmake.stash while you're cleaning up.

The script writingSystems.sh generates a list of writing systems,
ostensibly as a the basis for updating QFontDatabase::WritingSystem
enum; however, the Release 20 output of it contains many more writing
systems than are present in that enum, suggesting it has not been run
in a very long time. Further research needed.