[Interest] Qt4/Mac and newer Harfbuzz (> 1.4.1) (FYI)

[René J.V. Bertin]

Hi,

I'm not certain if there's still much of a point in filing bug reports for Qt4, so I'll just mention the issue I ran into yesterday here.

I've been using Harfbuzz text rendering on Mac, and started getting crashes with certain content after I upgraded the harfbuzz library to 1.7.6 .

I traced the crash to an out-of-boundary issue at the end of HB_HeuristicSetGlyphAttributes() in src/3rdparty/harfbuzz/src/harfbuzz-shaper.cpp, apparently because the function gets called with an item that has length=0.

I cannot say I understand the context, nor why this could happen when Qt4 apparently uses its own harfbuzz copy, but the issue is reproducible and can be avoided with this workaround:

https://github.com/RJVB/macstrop/blob/master/aqua/qt4-mac-devel/files/patch-harfbuzz-support.diff

Note that harfbuzz support is always built in, but either always active (`configure -harfbuzz`) or activatable with QT_ENABLE_HARFBUZZ=1 .

HtH,
R.