AssertionError in untyped function definition

[dfarley1]

Offending code:

protocol_page_translate.py
46:  
47:  
48:  def select_fields_to_translate(json_obj, translation):
49:      """Select Fields in Dashboard JSON to translate S --> C"""
50:      json_obj[".meta"] = translate_json(json_obj[".meta"], translation)

Calling code:

def select_fields_to_translate_file(filename, translation):
    with open(filename, "r") as f:
        try:
            bundle = json.load(f)
        except ValueError as error:
            print("{}: {}".format(filename, error), file=sys.stderr)
            return
    if not bundle:
        return
    bundle = select_fields_to_translate(bundle, translation).   <--- Here

Stacktrace:

protocol_page_translate.py:48: error: INTERNAL ERROR -- Please try using mypy master on Github:
https://mypy.rtfd.io/en/latest/common_issues.html#using-a-development-mypy-build
Please report a bug at https://github.com/python/mypy/issues
version: 0.760
Traceback (most recent call last):
  File "/usr/lib64/python3.6/runpy.py", line 193, in _run_module_as_main
    "__main__", mod_spec)
  File "/usr/lib64/python3.6/runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "/usr/lib64/python3.6/site-packages/mypy/__main__.py", line 12, in <module>
    main(None, sys.stdout, sys.stderr)
  File "/usr/lib64/python3.6/site-packages/mypy/main.py", line 89, in main
    res = build.build(sources, options, None, flush_errors, fscache, stdout, stderr)
  File "/usr/lib64/python3.6/site-packages/mypy/build.py", line 167, in build
    sources, options, alt_lib_path, flush_errors, fscache, stdout, stderr, extra_plugins
  File "/usr/lib64/python3.6/site-packages/mypy/build.py", line 235, in _build
    graph = dispatch(sources, manager, stdout)
  File "/usr/lib64/python3.6/site-packages/mypy/build.py", line 2611, in dispatch
    process_graph(graph, manager)
  File "/usr/lib64/python3.6/site-packages/mypy/build.py", line 2918, in process_graph
    process_stale_scc(graph, scc, manager)
  File "/usr/lib64/python3.6/site-packages/mypy/build.py", line 3017, in process_stale_scc
    graph[id].type_check_first_pass()
  File "/usr/lib64/python3.6/site-packages/mypy/build.py", line 2110, in type_check_first_pass
    self.type_checker().check_first_pass()
  File "/usr/lib64/python3.6/site-packages/mypy/checker.py", line 292, in check_first_pass
    self.accept(d)
  File "/usr/lib64/python3.6/site-packages/mypy/checker.py", line 399, in accept
    stmt.accept(self)
  File "/usr/lib64/python3.6/site-packages/mypy/nodes.py", line 676, in accept
    return visitor.visit_func_def(self)
  File "/usr/lib64/python3.6/site-packages/mypy/checker.py", line 724, in visit_func_def
    self._visit_func_def(defn)
  File "/usr/lib64/python3.6/site-packages/mypy/checker.py", line 728, in _visit_func_def
    self.check_func_item(defn, name=defn.name)
  File "/usr/lib64/python3.6/site-packages/mypy/checker.py", line 790, in check_func_item
    self.check_func_def(defn, typ, name)
  File "/usr/lib64/python3.6/site-packages/mypy/checker.py", line 833, in check_func_def
    self.check_for_missing_annotations(fdef)
  File "/usr/lib64/python3.6/site-packages/mypy/checker.py", line 1059, in check_for_missing_annotations
    code=codes.NO_UNTYPED_DEF)
  File "/usr/lib64/python3.6/site-packages/mypy/checker.py", line 4363, in fail
    self.msg.fail(msg, context, code=code)
  File "/usr/lib64/python3.6/site-packages/mypy/messages.py", line 148, in fail
    self.report(msg, context, 'error', code=code, file=file, origin=origin)
  File "/usr/lib64/python3.6/site-packages/mypy/messages.py", line 138, in report
    code=code)
  File "/usr/lib64/python3.6/site-packages/mypy/errors.py", line 319, in report
    self.add_error_info(info)
  File "/usr/lib64/python3.6/site-packages/mypy/errors.py", line 350, in add_error_info
    self._add_error_info(file, info)
  File "/usr/lib64/python3.6/site-packages/mypy/errors.py", line 322, in _add_error_info
    assert file not in self.flushed_files
AssertionError: 
protocol_page_translate.py:48: : note: use --pdb to drop into pdb

• What are the versions of mypy and Python you are using?
  Python 3.6, Mypy 0.760
• Do you see the same issue after installing mypy from Git master?
  Haven't tested yet
• What are the mypy flags you are using? (For example --strict-optional)
  --strict and a mypy.ini with a bunch of ignore_missing_imports for 3rd party libraries.

[ilevkivskyi]

I don't think this is caused by the actual code, but most likely is a duplicate of either #7510 or #4881