Build issues to debug for v1.086

[arrowtype]

Following my own build instructions, I run into issues in prepping the variable font build:

Traceback (most recent call last):
  File "/Users/stephennixon/type-repos/recursive/mastering/build.py", line 5, in <module>
    from build_files import buildFiles, getFolders
  File "/Users/stephennixon/type-repos/recursive/mastering/build_files.py", line 4, in <module>
    from prep_fonts import prep, copyFiles
  File "/Users/stephennixon/type-repos/recursive/mastering/prep_fonts.py", line 6, in <module>
    from designspaceProblems import DesignSpaceChecker
  File "/Users/stephennixon/type-repos/recursive/venv/lib/python3.11/site-packages/designspaceProblems/__init__.py", line 10, in <module>
    from ufoProcessor.ufoOperator import UFOOperator
ModuleNotFoundError: No module named 'ufoProcessor.ufoOperator'
Traceback (most recent call last):
  File "/Users/stephennixon/type-repos/recursive/mastering/build.py", line 5, in <module>
    from build_files import buildFiles, getFolders
  File "/Users/stephennixon/type-repos/recursive/mastering/build_files.py", line 4, in <module>
    from prep_fonts import prep, copyFiles
  File "/Users/stephennixon/type-repos/recursive/mastering/prep_fonts.py", line 6, in <module>
    from designspaceProblems import DesignSpaceChecker
  File "/Users/stephennixon/type-repos/recursive/venv/lib/python3.11/site-packages/designspaceProblems/__init__.py", line 10, in <module>
    from ufoProcessor.ufoOperator import UFOOperator
ModuleNotFoundError: No module named 'ufoProcessor.ufoOperator'

I’ll debug it and keep notes here.

[arrowtype]

Okay, that first issue was solved by pip installing ufoProcessor directly from its repo.

Now, onto new issues!

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Current blocker:

version=1.086 # (replace version number)                    
python build.py --varfiles --version $version
python build.py --variable --version $version
🚚 Building files for mastering

🚚 Generating sources
🏗  Copying files
🏗  Opening sources
🏗  Checking family name
🏗  Removing non-exporting glyphs
🏗  Decomposing scaled, flipped, and nested components
🏗  Clearing guides
🏗  Removing glyphs that aren't in every font
🏗  Removing non-compatible glyphs
🏗  Making kerning compatible
🏗  Sorting glyph order to be common
🏗  Setting production names
🏗  Setting version
🏗  Closing and saving sources
🏗  Checking full design space
🏗  Writing report
✅ Done preparing sources
🏗  Moved features into UFOs
🏗  Added mark, mkmk, and GDEF to features
Exception ignored in: <function UFOOperator.__del__ at 0x107390900>
Traceback (most recent call last):
  File "/Users/stephennixon/type-repos/recursive/venv/lib/python3.11/site-packages/ufoProcessor/ufoOperator.py", line 485, in __del__
  File "/Users/stephennixon/type-repos/recursive/venv/lib/python3.11/site-packages/ufoProcessor/ufoOperator.py", line 490, in changed
AttributeError: 'NoneType' object has no attribute 'keys'
🏗  Constructing variable font
Traceback (most recent call last):
  File "/Users/stephennixon/type-repos/recursive/mastering/build.py", line 66, in <module>
    build_variable(designspacePath=files["designspace"],
  File "/Users/stephennixon/type-repos/recursive/mastering/build_variable.py", line 147, in build_variable
    fp.build_variable_font(designspacePath,
  File "/Users/stephennixon/type-repos/recursive/venv/lib/python3.11/site-packages/fontmake/font_project.py", line 298, in build_variable_font
    font = ufo2ft.compileVariableTTF(
           ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/stephennixon/type-repos/recursive/venv/lib/python3.11/site-packages/ufo2ft/__init__.py", line 597, in compileVariableTTF
    fonts = compileVariableTTFs(designSpaceDoc, **kwargs)
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/stephennixon/type-repos/recursive/venv/lib/python3.11/site-packages/ufo2ft/__init__.py", line 663, in compileVariableTTFs
    vfNameToTTFont = varLib.build_many(
                     ^^^^^^^^^^^^^^^^^^
  File "/Users/stephennixon/type-repos/recursive/venv/lib/python3.11/site-packages/fontTools/varLib/__init__.py", line 1120, in build_many
    vf = build(
         ^^^^^^
  File "/Users/stephennixon/type-repos/recursive/venv/lib/python3.11/site-packages/fontTools/varLib/__init__.py", line 1209, in build
    _merge_OTL(vf, model, master_fonts, axisTags)
  File "/Users/stephennixon/type-repos/recursive/venv/lib/python3.11/site-packages/fontTools/varLib/__init__.py", line 758, in _merge_OTL
    merger.mergeTables(font, master_fonts, ["GSUB", "GDEF", "GPOS"])
  File "/Users/stephennixon/type-repos/recursive/venv/lib/python3.11/site-packages/fontTools/varLib/merger.py", line 156, in mergeTables
    self.mergeThings(font[tag], [m.get(tag) for m in master_ttfs])
  File "/Users/stephennixon/type-repos/recursive/venv/lib/python3.11/site-packages/fontTools/varLib/merger.py", line 1245, in mergeThings
    super(VariationMerger, self).mergeThings(out, lst)
  File "/Users/stephennixon/type-repos/recursive/venv/lib/python3.11/site-packages/fontTools/varLib/merger.py", line 143, in mergeThings
    self.mergeObjects(out, lst)
  File "/Users/stephennixon/type-repos/recursive/venv/lib/python3.11/site-packages/fontTools/varLib/merger.py", line 114, in mergeObjects
    mergerFunc(self, value, values)
  File "/Users/stephennixon/type-repos/recursive/venv/lib/python3.11/site-packages/fontTools/varLib/merger.py", line 1245, in mergeThings
    super(VariationMerger, self).mergeThings(out, lst)
  File "/Users/stephennixon/type-repos/recursive/venv/lib/python3.11/site-packages/fontTools/varLib/merger.py", line 143, in mergeThings
    self.mergeObjects(out, lst)
  File "/Users/stephennixon/type-repos/recursive/venv/lib/python3.11/site-packages/fontTools/varLib/merger.py", line 114, in mergeObjects
    mergerFunc(self, value, values)
  File "/Users/stephennixon/type-repos/recursive/venv/lib/python3.11/site-packages/fontTools/varLib/merger.py", line 1245, in mergeThings
    super(VariationMerger, self).mergeThings(out, lst)
  File "/Users/stephennixon/type-repos/recursive/venv/lib/python3.11/site-packages/fontTools/varLib/merger.py", line 143, in mergeThings
    self.mergeObjects(out, lst)
  File "/Users/stephennixon/type-repos/recursive/venv/lib/python3.11/site-packages/fontTools/varLib/merger.py", line 114, in mergeObjects
    mergerFunc(self, value, values)
  File "/Users/stephennixon/type-repos/recursive/venv/lib/python3.11/site-packages/fontTools/varLib/merger.py", line 1245, in mergeThings
    super(VariationMerger, self).mergeThings(out, lst)
  File "/Users/stephennixon/type-repos/recursive/venv/lib/python3.11/site-packages/fontTools/varLib/merger.py", line 148, in mergeThings
    raise ShouldBeConstant(self, expected=out, got=lst)
fontTools.varLib.errors.ShouldBeConstant: 

Couldn't merge the fonts, because some values were different, but should have
been the same. This happened while performing the following operation:
GPOS.table.FeatureList.FeatureCount

The problem is likely to be in Recursive Mono Casual A Slanted:
Expected to see .FeatureCount==5, instead saw 3

Incompatible features between masters.
Expected: kern, kern, kern, mark, mkmk.
Got: kern, mark, mkmk.

In the varfontprep-report.txt, there is a line saying that kerning is different... This is what I’ll investigate next.

[kerning: kerning group does not match / public.kern1.H_right: ['H', 'Hbrevebelow', 'Hcircumflex', 'Hdotbelow', 'N', 'Nacute', 'Ncaron', 'Ncommaaccent', 'Ndot', 'Ndotbelow', 'Nlinebelow', 'Ntilde', 'U', 'Uacute', 'Ubreve', 'Ucircumflex', 'Udieresis', 'Udotbelow', 'Ugrave', 'Ugravedbl', 'Uhook', 'Uhorn', 'Uhornacute', 'Uhorndot', 'Uhorngrave', 'Uhornhook', 'Uhorntilde', 'Uhungarumlaut', 'Uinvertedbreve', 'Umacron', 'Umacrondieresis', 'Uogonek', 'Uring', 'Utilde', 'Utildeacute', 'Eng', 'LJ', 'NJ', 'Nhookleft', 'd', 'ddotbelow', 'dlinebelow'], ['H', 'Hbrevebelow', 'Hcircumflex', 'Hdotbelow', 'N', 'Nacute', 'Ncaron', 'Ncommaaccent', 'Ndot', 'Ndotbelow', 'Nlinebelow', 'Ntilde', 'U', 'Uacute', 'Ubreve', 'Ucircumflex', 'Udieresis', 'Udotbelow', 'Ugrave', 'Ugravedbl', 'Uhook', 'Uhorn', 'Uhornacute', 'Uhorndot', 'Uhorngrave', 'Uhornhook', 'Uhorntilde', 'Uhungarumlaut', 'Uinvertedbreve', 'Umacron', 'Umacrondieresis', 'Uogonek', 'Uring', 'Utilde', 'Utildeacute', 'Eng', 'LJ', 'NJ', 'Nhookleft', 'd', 'ddotbelow', 'dlinebelow', 'one.sans'], font: Recursive Sans Casual B, groupName: public.kern1.H_right (5, 2)]

[arrowtype]

Well, I’m not yet sure how to get past this, so it’ll take more digging.

I think the solution may lie in understanding and fixing this early part of the above traceback:

🏗  Added mark, mkmk, and GDEF to features
Exception ignored in: <function UFOOperator.__del__ at 0x107390900>
Traceback (most recent call last):
  File "/Users/stephennixon/type-repos/recursive/venv/lib/python3.11/site-packages/ufoProcessor/ufoOperator.py", line 485, in __del__
  File "/Users/stephennixon/type-repos/recursive/venv/lib/python3.11/site-packages/ufoProcessor/ufoOperator.py", line 490, in changed
AttributeError: 'NoneType' object has no attribute 'keys'

[arrowtype]

Another possible issue causing the build failure is detailed at googlefonts/fontmake#894.

Basically, ufo2ft now splits kerning by script, and the Sans sources for Recursive have kerning for /pi and other Greek characters. I’ll try adding some blank kerns for Greek into the Mono sources, and see whether that makes a difference here.

Also, re: "In the varfontprep-report.txt, there is a line saying that kerning is different... This is what I’ll investigate next." I see that the second font in that list includes one.sans in the list. So, I’ll set groups to be the same, again.

[arrowtype]

Adding blank kerning to mono sources for /pi /pi actually did help, but didn't fully solve things:

Couldn't merge the fonts, because some values were different, but should have
been the same. This happened while performing the following operation:
GPOS.table.FeatureList.FeatureCount

The problem is likely to be in Recursive Mono Casual A Slanted:
Expected to see .FeatureCount==5, instead saw 4

Incompatible features between masters.
Expected: kern, kern, kern, mark, mkmk.
Got: kern, kern, mark, mkmk.

Next, I’ll debug the ufoOperator traceback.