Internal error

[sharmaeklavya2]

I ran the latest mypy from master (commit 13b7573) and I got an internal error. I didn't get this error with mypy version 0.511.

File which caused the traceback: https://github.com/zulip/zulip/blob/master/api/integrations/perforce/git_p4.py
This was the only file I ran mypy on.

I didn't use any extra flags with mypy (except --tb to generate the traceback once I got the internal error).

Here's the traceback:

api/integrations/perforce/git_p4.py: error: INTERNAL ERROR -- please report a bug at https://github.com/python/mypy/issues version: 0.520-dev-13b75737bb41d62ae4e7714704dcda3b446fa9f4
Traceback (most recent call last):
  File "/mnt/code/venvs/mypy_venv/bin/mypy", line 6, in <module>
    main(__file__)
  File "/mnt/code/venvs/mypy_venv/lib/python3.5/site-packages/mypy/main.py", line 46, in main
    res = type_check_only(sources, bin_dir, options)
  File "/mnt/code/venvs/mypy_venv/lib/python3.5/site-packages/mypy/main.py", line 93, in type_check_only
    options=options)
  File "/mnt/code/venvs/mypy_venv/lib/python3.5/site-packages/mypy/build.py", line 188, in build
    graph = dispatch(sources, manager)
  File "/mnt/code/venvs/mypy_venv/lib/python3.5/site-packages/mypy/build.py", line 1587, in dispatch
    graph = load_graph(sources, manager)
  File "/mnt/code/venvs/mypy_venv/lib/python3.5/site-packages/mypy/build.py", line 1670, in load_graph
    root_source=True)
  File "/mnt/code/venvs/mypy_venv/lib/python3.5/site-packages/mypy/build.py", line 1259, in __init__
    self.parse_file()
  File "/mnt/code/venvs/mypy_venv/lib/python3.5/site-packages/mypy/build.py", line 1442, in parse_file
    first.visit_file(self.tree, self.xpath, self.id, self.options)
  File "/usr/lib/python3.5/contextlib.py", line 77, in __exit__
    self.gen.throw(type, value, traceback)
  File "/mnt/code/venvs/mypy_venv/lib/python3.5/site-packages/mypy/build.py", line 1347, in wrap_context
    yield
  File "/mnt/code/venvs/mypy_venv/lib/python3.5/site-packages/mypy/build.py", line 1442, in parse_file
    first.visit_file(self.tree, self.xpath, self.id, self.options)
  File "/mnt/code/venvs/mypy_venv/lib/python3.5/site-packages/mypy/semanal.py", line 3423, in visit_file
    d.accept(self)
  File "/mnt/code/venvs/mypy_venv/lib/python3.5/site-packages/mypy/nodes.py", line 1007, in accept
    return visitor.visit_try_stmt(self)
  File "/mnt/code/venvs/mypy_venv/lib/python3.5/site-packages/mypy/semanal.py", line 3614, in visit_try_stmt
    self.sem.analyze_try_stmt(s, self, add_global=self.sem.is_module_scope())
  File "/mnt/code/venvs/mypy_venv/lib/python3.5/site-packages/mypy/semanal.py", line 2632, in analyze_try_stmt
    handler.accept(visitor)
  File "/mnt/code/venvs/mypy_venv/lib/python3.5/site-packages/mypy/nodes.py", line 811, in accept
    return visitor.visit_block(self)
  File "/mnt/code/venvs/mypy_venv/lib/python3.5/site-packages/mypy/semanal.py", line 3458, in visit_block
    node.accept(self)
  File "/mnt/code/venvs/mypy_venv/lib/python3.5/site-packages/mypy/nodes.py", line 750, in accept
    return visitor.visit_class_def(self)
  File "/mnt/code/venvs/mypy_venv/lib/python3.5/site-packages/mypy/semanal.py", line 3526, in visit_class_def
    self.sem.check_no_global(cdef.name, cdef)
  File "/mnt/code/venvs/mypy_venv/lib/python3.5/site-packages/mypy/semanal.py", line 3318, in check_no_global
    self.name_already_defined(n, ctx, self.globals[n])
  File "/mnt/code/venvs/mypy_venv/lib/python3.5/site-packages/mypy/semanal.py", line 3330, in name_already_defined
    extra_msg = ' on line {}'.format(original_ctx.node.get_line())
AttributeError: 'NoneType' object has no attribute 'get_line'
api/integrations/perforce/git_p4.py: note: use --pdb to drop into pdb

[sharmaeklavya2]

I found a smaller reproducer:

try:
    from subprocess import CalledProcessError
except ImportError:
    class CalledProcessError(object):
        pass

[gvanrossum]

Could you bisect it?

[ilevkivskyi]

I think #3396 is to blame. @pkch could you please take a look?

[pkch]

Yeah, it's my mistake. Please check the PR.

[gvanrossum]

So since you withdrew the fix we need to merge the revert, right?

[pkch]

Yup, resubmitting the fix now.