Generating font from source has issues with Cyrillic kerning pairs

[pennig]

I get many "ambiguously connected by several anchor classes" INFO messages from the python script when running it. This also results in a font that has significant kerning differences when comparing the generated fonts with the ones available for download. A sample:

INFO:ufo2ft.featureWriters.markFeatureWriter.MarkFeatureWriter:The base glyph O-cy and mark glyph psilicyrcomb.case are ambiguously connected by several anchor classes: MC_onRight, MC_Top. The last one will prevail.
INFO:ufo2ft.featureWriters.markFeatureWriter.MarkFeatureWriter:The base glyph O-cy and mark glyph psilioxiacomb.case are ambiguously connected by several anchor classes: MC_onRight, MC_Top. The last one will prevail.
INFO:ufo2ft.featureWriters.markFeatureWriter.MarkFeatureWriter:The base glyph O-cy and mark glyph psilivariacomb.case are ambiguously connected by several anchor classes: MC_onRight, MC_Top. The last one will prevail.

I'm not sure whether this is FontLab's issue, or a python package version issue. This is particularly because FontLab crashes when done executing the script, and the fonttools python packages listed in the README no longer exist under the @feaLib-STAT tag.

Guidance would be appreciated.

[twardoch]

How exactly are you building the font, in which version of FontLab?

[pennig]

For building, I'm following the instructions from the README verbatim, save for the python3 install step, where I remove the @feaLib-STAT tag (to install the latest versions of those packages)
I'm using FontLab 7.2.0.7644 (on Big Sur)

[pennig]

I should note that the output .ttf files are significantly smaller in size as well. Seems like kerning pairs or hinting is getting lost along the way someplace.

[pennig]

@twardoch I hope you're doing well. Do you have any spare cycles to look into this, or perhaps more simply, #19 & #20? Removing the "(t)" symbol (leaving everything else untouched) was my ultimate goal in the "build Lato at home" endeavor that prompted this ticket.

[ronaldtse]

I am also getting the same "ambiguously connected" messages.

According to the README I'm using these commands (again, same issue as you encountered that the @feaLib-STAT tag no longer exists):

python3 -m pip install --user --upgrade fonttools fontmake afdko psautohint
python3 tools/03_build_lato_fontmake.py

I get these sizes:

$ ls -l ../build/Lato3Upr2M/static-otf/
366K Lato-Black.otf
433K Lato-Bold.otf
399K Lato-Hairline.otf
432K Lato-Heavy.otf
423K Lato-Light.otf
426K Lato-Medium.otf
434K Lato-Regular.otf
429K Lato-Semibold.otf
426K Lato-Thin.otf

$ ls -l ../build/Lato3Upr2M/static-ttf/
439K Lato-Black.ttf
473K Lato-Bold.ttf
469K Lato-Hairline.ttf
474K Lato-Heavy.ttf
472K Lato-Light.ttf
473K Lato-Medium.ttf
473K Lato-Regular.ttf
473K Lato-Semibold.ttf
472K Lato-Thin.ttf