qt5base-lts/util/unicode/README
Edward Welbourne 1a1718b342 Add missing docs for UCD additions at 5.15
Also remove two stray commas pointed out in code-review and some
others noticed on checking for similar.
This amends commit c3eb521a0f.

Change-Id: If20c5146b740defe8d25ff61d399031b5c66ded1
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
2019-11-28 11:04:27 +01:00

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Unicode is used to generate the unicode data in src/corelib/text/.
To update:
* Find the data (UAX #44, UCD; not the XML version) at
ftp://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/. (These last are
only in the zip, not in the web-space's unpacked versions.)
* In tst_QTextBoundaryFinder's data/ sub-directory, update its files
from the auxiliary/ sub-directory of the UCD data.
* 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.
* 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.