[subset] Subr subsetting fails on some CID-keyed CFF

Recently an issue with --no-hinting was fixed in #709, but I’m getting another error when subsetting a CID-keyed CFF:

$ pyftsubset OurAwesomeUnreleasedFont.otf --no-hinting --text="情"
Traceback (most recent call last):
  File "/Users/mnakamura/.pyenv/versions/fonttools-2.7.13/bin/pyftsubset", line 11, in <module>
    load_entry_point('fonttools', 'console_scripts', 'pyftsubset')()
  File "/Users/mnakamura/.ghq/github.com/mashabow/fonttools/Lib/fontTools/misc/loggingTools.py", line 372, in wrapper
    return func(*args, **kwds)
  File "/Users/mnakamura/.ghq/github.com/mashabow/fonttools/Lib/fontTools/subset/__init__.py", line 2975, in main
    subsetter.subset(font)
  File "/Users/mnakamura/.ghq/github.com/mashabow/fonttools/Lib/fontTools/subset/__init__.py", line 2789, in subset
    self._prune_post_subset(font)
  File "/Users/mnakamura/.ghq/github.com/mashabow/fonttools/Lib/fontTools/subset/__init__.py", line 2772, in _prune_post_subset
    retain = table.prune_post_subset(self.options)
  File "/Users/mnakamura/.ghq/github.com/mashabow/fonttools/Lib/fontTools/subset/__init__.py", line 2281, in prune_post_subset
    subr.subset_subroutines (local_subrs, font.GlobalSubrs)
  File "/Users/mnakamura/.ghq/github.com/mashabow/fonttools/Lib/fontTools/subset/__init__.py", line 1917, 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'

According to Lib/fontTools/subset/__init__.py#L2266-L2281, when processing the GlobalSubrs, the value of local_subrs is always [] even if there are actually some local subrs. This seems to cause the error in subr.subset_subroutines().

Note that this font hasn’t been released yet, so unfortunately we cannot provide samples for now.

[miguelsousa]

Team work \o/

[behdad]

But if any of the global subroutines in turn contains a callsubr command, the call to subr.subset_subroutines method fails because it expects that these local_surbs have _used attribute, which of course they can’t have.

Ah, you just successfully debugged https://github.com/fonttools/fonttools/issues/656 ! Thank you!!! Let me think about this a bit.