Some Sphinx roles in subcommand descriptions cause a crash

[akaihola]

It seems that most Sphinx roles, when used in the description of an argparse subcommand, cause sphinx-argparse to crash. The ones listed under "Other semantic markup" on the Roles Sphinx documentation page seems to work correctly, though.

Here is a minimal Sphinx project to reproduce this problem:

conf.py

extensions = ['sphinxarg.ext']

contents.rst

.. argparse::
   :module: sphinxtest
   :func: get_parser

sphinxtest.py

import argparse

def get_parser():
    parser = argparse.ArgumentParser()
    subparsers = parser.add_subparsers()
    subparsers.add_parser('subcmd', description=':file:`role` makes sphinx-argparse fail')
    return parser

Build command (full virtualenv paths omitted for brevity)

$ rm html -rf ; PYTHONPATH=. sphinx-build -v . html     
Running Sphinx v1.7.2
making output directory...
loading pickled environment... not yet created
building [mo]: targets for 0 po files that are out of date
building [html]: targets for 1 source files that are out of date
updating environment: 1 added, 0 changed, 0 removed
reading sources... [100%] contents

Traceback (most recent call last):
  File "docutils/statemachine.py", line 307, in next_line
    self.line = self.input_lines[self.line_offset]
  File "docutils/statemachine.py", line 1152, in __getitem__
    return self.data[i]
IndexError: list index out of range

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "docutils/statemachine.py", line 230, in run
    self.next_line()
  File "docutils/statemachine.py", line 310, in next_line
    raise EOFError
EOFError

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "sphinx/cmdline.py", line 304, in main
    app.build(args.force_all, filenames)
  File "sphinx/application.py", line 331, in build
    self.builder.build_update()
  File "sphinx/builders/__init__.py", line 338, in build_update
    'out of date' % len(to_build))
  File "sphinx/builders/__init__.py", line 351, in build
    updated_docnames = set(self.env.update(self.config, self.srcdir, self.doctreedir))
  File "sphinx/environment/__init__.py", line 565, in update
    self._read_serial(docnames, self.app)
  File "sphinx/environment/__init__.py", line 584, in _read_serial
    self.read_doc(docname, app)
  File "sphinx/environment/__init__.py", line 659, in read_doc
    doctree = read_doc(self.app, self, self.doc2path(docname))
  File "sphinx/io.py", line 294, in read_doc
    pub.publish()
  File "docutils/core.py", line 217, in publish
    self.settings)
  File "docutils/readers/__init__.py", line 72, in read
    self.parse()
  File "docutils/readers/__init__.py", line 78, in parse
    self.parser.parse(self.input, document)
  File "sphinx/parsers.py", line 85, in parse
    self.statemachine.run(inputstring, document, inliner=self.inliner)
  File "docutils/parsers/rst/states.py", line 171, in run
    input_source=document['source'])
  File "docutils/statemachine.py", line 239, in run
    context, state, transitions)
  File "docutils/statemachine.py", line 460, in check_line
    return method(match, context, next_state)
  File "docutils/parsers/rst/states.py", line 2326, in explicit_markup
    nodelist, blank_finish = self.explicit_construct(match)
  File "docutils/parsers/rst/states.py", line 2338, in explicit_construct
    return method(self, expmatch)
  File "docutils/parsers/rst/states.py", line 2081, in directive
    directive_class, match, type_name, option_presets)
  File "docutils/parsers/rst/states.py", line 2130, in run_directive
    result = directive_instance.run()
  File "sphinxarg/ext.py", line 486, in run
    settings=self.state.document.settings))
  File "sphinxarg/ext.py", line 192, in print_subcommands
    for element in renderList(desc, markDownHelp):
  File "sphinxarg/ext.py", line 66, in renderList
    Parser().parse('\n\n'.join(l) + '\n', document)
  File "docutils/parsers/rst/__init__.py", line 191, in parse
    self.statemachine.run(inputlines, document, inliner=self.inliner)
  File "docutils/parsers/rst/states.py", line 171, in run
    input_source=document['source'])
  File "docutils/statemachine.py", line 245, in run
    result = state.eof(context)
  File "docutils/parsers/rst/states.py", line 2696, in eof
    self.blank(None, context, None)
  File "docutils/parsers/rst/states.py", line 2688, in blank
    context, self.state_machine.abs_line_number() - 1)
  File "docutils/parsers/rst/states.py", line 418, in paragraph
    textnodes, messages = self.inline_text(text, lineno)
  File "docutils/parsers/rst/states.py", line 427, in inline_text
    return self.inliner.parse(text, lineno, self.memo, self.parent)
  File "docutils/parsers/rst/states.py", line 645, in parse
    lineno)
  File "docutils/parsers/rst/states.py", line 787, in interpreted_or_phrase_ref
    lineno)
  File "docutils/parsers/rst/states.py", line 871, in interpreted
    nodes, messages2 = role_fn(role, rawsource, text, lineno, self)
  File "sphinx/roles.py", line 292, in emph_literal_role
    env = inliner.document.settings.env
AttributeError: 'Values' object has no attribute 'env'

Exception occurred:
  File "sphinx/roles.py", line 292, in emph_literal_role
    env = inliner.document.settings.env
AttributeError: 'Values' object has no attribute 'env'
The full traceback has been saved in /tmp/sphinx-err-kdcf92c8.log, if you want to report the issue to the developers.
Please also report this if it was a user error, so that a better error message can be provided next time.
A bug report can be filed in the tracker at <https://github.com/sphinx-doc/sphinx/issues>. Thanks!