shells/xonsh fail with python39

[Chavdar Ivanov <ci4ic4%gmail.com@localhost>]

Hi,
I am in the process of switching my pkgsrc setup from python3.7 to
3.9. shells/xonsh is supposed to work with python version >= 3.7, but
with 3.9 I am getting in the 'make package' stage:

....
running install
Building lexer and parser tables.
ERROR: /usr/pkgsrc/shells/xonsh/work/xonsh-0.8.8/xonsh/parsers/base.py:3262:
Symbol '__peg_parser___tok' used, but not defined as a token or a rule
Traceback (most recent call last):
  File "/usr/pkgsrc/shells/xonsh/work/xonsh-0.8.8/setup.py", line 412,
in <module>
    main()
  File "/usr/pkgsrc/shells/xonsh/work/xonsh-0.8.8/setup.py", line 408, in main
    setup(**skw)
  File "/usr/pkg/lib/python3.9/site-packages/setuptools/__init__.py",
line 153, in setup
    return distutils.core.setup(**attrs)
  File "/usr/pkg/lib/python3.9/distutils/core.py", line 148, in setup
    dist.run_commands()
  File "/usr/pkg/lib/python3.9/distutils/dist.py", line 966, in run_commands
    self.run_command(cmd)
  File "/usr/pkg/lib/python3.9/distutils/dist.py", line 985, in run_command
    cmd_obj.run()
  File "/usr/pkgsrc/shells/xonsh/work/xonsh-0.8.8/setup.py", line 214, in run
    build_tables()
  File "/usr/pkgsrc/shells/xonsh/work/xonsh-0.8.8/setup.py", line 90,
in build_tables
    Parser(
  File "/usr/pkgsrc/shells/xonsh/work/xonsh-0.8.8/xonsh/lazyasd.py",
line 79, in __call__
    return obj(*args, **kwargs)
  File "/usr/pkgsrc/shells/xonsh/work/xonsh-0.8.8/xonsh/parsers/v35.py",
line 38, in __init__
    super().__init__(
  File "/usr/pkgsrc/shells/xonsh/work/xonsh-0.8.8/xonsh/parsers/base.py",
line 508, in __init__
    self.parser = yacc.yacc(**yacc_kwargs)
  File "/usr/pkg/lib/python3.9/site-packages/ply/yacc.py", line 3432, in yacc
    raise YaccError('Unable to build parser')
ply.yacc.YaccError: Unable to build parser
*** Error code 1

Stop.
make[1]: stopped in /usr/pkgsrc/shells/xonsh
*** Error code 1
...

Any hints?

Chavdar


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