A reproduced subsetting issue when trying w/ a CJK font

[WinterholdPrime]

Hi all, I think I am reproducing a problem similar to #856. I am using a CJK font named Glow Sans (link, they are open source). When I tried to subset, it failed.
GlowSansSC-Extended-Medium.zip
I followed #856 but I am still confused how the issue was solved. Could anyone hint me? THX!

  fonttools subset "GlowSansSC-Extended-Medium.otf" --text=" 谟涅摩叙研究站删除部门無无关紧要等级收容类型次扰动风险特殊措施描述本文档已被标记为待理解乃是暴露的内禀过程且很可能有误附篇讨论之地点出席方序言不适用结束交互显示隐藏单击以放大危害性数据移信息图像未找到行后果脚注及参考：，。[]" --output-file="GlowSansSCExtMed_7912.otf"
>>
Traceback (most recent call last):
  File "C:\Program Files\WindowsApps\PythonSoftwareFoundation.Python.3.9_3.9.3568.0_x64__qbz5n2kfra8p0\lib\runpy.py", line 197, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File "C:\Program Files\WindowsApps\PythonSoftwareFoundation.Python.3.9_3.9.3568.0_x64__qbz5n2kfra8p0\lib\runpy.py", line 87, in _run_code
    exec(code, run_globals)
  File "C:\Users\zhang\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.9_qbz5n2kfra8p0\LocalCache\local-packages\Python39\Scripts\fonttools.exe\__main__.py", line 7, in <module>
  File "C:\Users\zhang\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.9_qbz5n2kfra8p0\LocalCache\local-packages\Python39\site-packages\fontTools\__main__.py", line 31, in main
    runpy.run_module(mod, run_name="__main__")
  File "C:\Program Files\WindowsApps\PythonSoftwareFoundation.Python.3.9_3.9.3568.0_x64__qbz5n2kfra8p0\lib\runpy.py", line 228, in run_module
    return _run_code(code, {}, init_globals, run_name, mod_spec)
  File "C:\Program Files\WindowsApps\PythonSoftwareFoundation.Python.3.9_3.9.3568.0_x64__qbz5n2kfra8p0\lib\runpy.py", line 87, in _run_code
    exec(code, run_globals)
  File "C:\Users\zhang\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.9_qbz5n2kfra8p0\LocalCache\local-packages\Python39\site-packages\fontTools\subset\__main__.py", line 6, in <module>
    sys.exit(main())
  File "C:\Users\zhang\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.9_qbz5n2kfra8p0\LocalCache\local-packages\Python39\site-packages\fontTools\misc\loggingTools.py", line 375, in wrapper
    return func(*args, **kwds)
  File "C:\Users\zhang\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.9_qbz5n2kfra8p0\LocalCache\local-packages\Python39\site-packages\fontTools\subset\__init__.py", line 3686, in main
    subsetter.subset(font)
  File "C:\Users\zhang\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.9_qbz5n2kfra8p0\LocalCache\local-packages\Python39\site-packages\fontTools\subset\__init__.py", line 3479, in subset
    self._prune_post_subset(font)
  File "C:\Users\zhang\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.9_qbz5n2kfra8p0\LocalCache\local-packages\Python39\site-packages\fontTools\subset\__init__.py", line 3462, in _prune_post_subset
    retain = table.prune_post_subset(font, self.options)
  File "C:\Users\zhang\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.9_qbz5n2kfra8p0\LocalCache\local-packages\Python39\site-packages\fontTools\subset\cff.py", line 380, in prune_post_subset
    self.remove_unused_subroutines()
  File "C:\Users\zhang\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.9_qbz5n2kfra8p0\LocalCache\local-packages\Python39\site-packages\fontTools\subset\cff.py", line 525, in remove_unused_subroutines
    subr.subset_subroutines(local_subrs, font.GlobalSubrs)
  File "C:\Users\zhang\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.9_qbz5n2kfra8p0\LocalCache\local-packages\Python39\site-packages\fontTools\subset\cff.py", line 141, in subset_subroutines
    p[i - 1] = subrs._used.index(p[i - 1] + subrs._old_bias) - subrs._new_bias
AttributeError: 'list' object has no attribute '_used'

[behdad]

First things first, what version of fonttools are you using?

[WinterholdPrime]

Hi, I am using python 3.9.13 and fonttools 4.42.1

[behdad]

I can reproduce the issue. Lemme find a fix.

[behdad]

This suggests a broken font. I don't know how to fix it. It's referencing subroutines in an FDArray that doesn't have Subroutines as far as I see.

[behdad]

So this is a font that both has Private.Subrs, AND an FDArray. And the GlobalSubrs refer to local subrs but we don't collect those because the GlobalSubrs are called with the FDArray Subrs only. I don't know how to "fix" this.

[WinterholdPrime]

Okay Behdad, thanks a lot for checking this!