qt5base-lts/tests/auto/gui/text/qglyphrun
Eskil Abrahamsen Blomfeldt fccd419dd6 Remove false Q_UNREACHABLE from shaping code
This was added by 9ff76c27b9 on
the basis that it signifies a shaping error and would later assert
or crash.

But the line is easily reachable by user code. If Harfbuzz returns
0 glyphs, it just means it is unable to shape the string, for instance
if the input string only contains default ignorables (like a ZWJ)
and does not have any appropriate glyph to use for replacement.

Qt expects there to always be at least one glyph in the output
(num_glyphs == 0 is used to indicate shaping is not yet done), so
to avoid asserts later on, we simply populate the output with a
single 0 token, which is a required entry in the font that is
reserved for representing unrepresentable characters.

This also adds a test and therefore a zero-width joiner to the test
font to reproduce the issue.

[ChangeLog][QtGui][Text] Fixed a possible crash with certain fonts
when shaping strings consisting only of control characters.

Fixes: QTBUG-89155
Pick-to: 5.15
Pick-to: 6.0
Change-Id: Ia0dd6a04844c9be90dcab6c464bebe339a3dab11
Reviewed-by: Konstantin Ritt <ritt.ks@gmail.com>
2021-02-03 09:44:44 +01:00
..
BLACKLIST Remove blacklisting for b2qt tests that now pass 2021-01-28 09:27:14 +02:00
CMakeLists.txt CMake: Regenerate projects to use new qt_internal_ API 2020-09-23 16:59:06 +02:00
testdata.qrc
tst_qglyphrun.cpp Remove false Q_UNREACHABLE from shaping code 2021-02-03 09:44:44 +01:00