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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Max recursion errors for mathtext on Python 3.6 / OSX","articleBody":"See: https://github.com/MacPython/matplotlib-wheels/issues/3\r\n\r\nErrors occur testing 1.5.3 and current `v2.x` branch on Python 3.6, OSX.\r\n\r\n```\r\n======================================================================\r\nERROR: matplotlib.tests.test_mathtext.test_mathtext_cm_53.test\r\n----------------------------------------------------------------------\r\nTraceback (most recent call last):\r\n  File \"/Users/travis/build/MacPython/matplotlib-wheels/venv/lib/python3.6/site-packages/nose/case.py\", line 198, in runTest\r\n    self.test(*self.arg)\r\n  File \"/Users/travis/build/MacPython/matplotlib-wheels/venv/lib/python3.6/site-packages/matplotlib/testing/decorators.py\", line 53, in failer\r\n    result = f(*args, **kwargs)\r\n  File \"/Users/travis/build/MacPython/matplotlib-wheels/venv/lib/python3.6/site-packages/matplotlib/testing/decorators.py\", line 207, in do_test\r\n    figure.savefig(actual_fname, **self._savefig_kwarg)\r\n  File \"/Users/travis/build/MacPython/matplotlib-wheels/venv/lib/python3.6/site-packages/matplotlib/figure.py\", line 1563, in savefig\r\n\r\n[snip]\r\n\r\n File \"/Users/travis/build/MacPython/matplotlib-wheels/venv/lib/python3.6/site-packages/pyparsing.py\", line 1510, in _parseCache\r\n    value = cache.get(lookup)\r\n  File \"/Users/travis/build/MacPython/matplotlib-wheels/venv/lib/python3.6/site-packages/pyparsing.py\", line 1459, in get\r\n    return cache.get(key, not_in_cache)\r\nRecursionError: maximum recursion depth exceeded\r\n```\r\n\r\nhttps://s3.amazonaws.com/archive.travis-ci.org/jobs/187592465/log.txt\r\n\r\nFurther investigation reveals:\r\n\r\n* error does not occur when running the individual mathtext tests, e.g. with `python tests.py matplotlib.tests.test_mathtext`, but only when running these tests as part of a full test suite `python tests.py`;\r\n* when dropping into the debugger on the test failure - `python tests.py --pdb` - this sequence of commands also cause the recursion error:\r\n\r\n```\r\nfrom matplotlib.font_manager import FontProperties\r\nfrom matplotlib import mathtext as mt\r\n\r\nmy_p = mt.Parser()\r\nbackend = mt.MathtextBackendPath()\r\nfont_output = mt.BakomaFonts(FontProperties(), backend)\r\nmy_str = '$\\\\sqrt{1+\\\\sqrt{1+\\\\sqrt{1+\\\\sqrt{1+\\\\sqrt{1+\\\\sqrt{1+\\\\sqrt{1+x}}}}}}}$'\r\nmy_p._state_stack = [my_p.State(font_output, 'default', 'rm', 100, 72)]\r\nmy_p._em_width_cache = {}\r\nresult = my_p._expression.parseString(my_str)\r\nprint(result)\r\n```\r\n\r\nThe same sequence of commands run on its own in Python 3.6, passes.\r\n\r\nThis string also generates the recursion errors, when dropped into the debugger:\r\n\r\n```\r\nr'$\\cos{1 + \\sqrt{1 + \\sqrt{1 + \\sqrt{1 + \\sqrt{1 + \\sqrt{1+\\cos{1+x}}}}}}}$'\r\n```\r\n\r\nbut not:\r\n\r\n```\r\nr'$\\cos{1 + \\sqrt{1 + \\sqrt{1 + \\sqrt{1 + \\sqrt{1 + \\cos{1+\\cos{1+x}}}}}}}$'\r\nr'$\\cos{1 + \\cos{1 + \\cos{1 + \\cos{1 + \\cos{1 + \\cos{1+\\cos{1+x}}}}}}}$'\r\nr'$\\sqrt{1 + \\sqrt{1 + \\sqrt{1 + \\sqrt{1 + \\sqrt{1+\\sqrt{1+x}}}}}}$'\r\n```\r\n\r\nIt looks like there is some horrible global state in the MathText module or pyparsing that is being triggered only under certain circumstances.\r\n\r\n@mdboom - can you reproduce?   Any insights into the problem?","author":{"url":"https://github.com/matthew-brett","@type":"Person","name":"matthew-brett"},"datePublished":"2017-01-11T05:32:03.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":13},"url":"https://github.com/7799/matplotlib/issues/7799"}