Problems using Python 3.9

[thepabloaguilar]

Bug report

What's wrong

I know Python 3.9 was too recent released but I would like do adopt it in some projects, when I try to run wemake-python-styleguide using the 3.9 version I get the following error:

Traceback (most recent call last):
  File "/home/runner/work/returns/returns/.venv/lib/python3.9/site-packages/wemake_python_styleguide/checker.py", line 154, in run
    visitor.run()
  File "/home/runner/work/returns/returns/.venv/lib/python3.9/site-packages/wemake_python_styleguide/visitors/base.py", line 191, in run
    self.visit(self.tree)
  File "/home/runner/work/returns/returns/.venv/lib/python3.9/site-packages/wemake_python_styleguide/visitors/base.py", line 186, in visit
    return route_visit(self, tree)
  File "/home/runner/work/returns/returns/.venv/lib/python3.9/site-packages/wemake_python_styleguide/compat/routing.py", line 36, in route_visit
    return getattr(
  File "/opt/hostedtoolcache/Python/3.9.0/x64/lib/python3.9/ast.py", line 415, in generic_visit
    self.visit(item)
  File "/home/runner/work/returns/returns/.venv/lib/python3.9/site-packages/wemake_python_styleguide/visitors/base.py", line 186, in visit
    return route_visit(self, tree)
  File "/home/runner/work/returns/returns/.venv/lib/python3.9/site-packages/wemake_python_styleguide/compat/routing.py", line 36, in route_visit
    return getattr(
  File "/home/runner/work/returns/returns/.venv/lib/python3.9/site-packages/wemake_python_styleguide/visitors/ast/complexity/annotations.py", line 34, in visit_any_function
    self._check_function_annotations_complexity(node)
  File "/home/runner/work/returns/returns/.venv/lib/python3.9/site-packages/wemake_python_styleguide/visitors/ast/complexity/annotations.py", line 58, in _check_function_annotations_complexity
    self._check_annotations_complexity(node, annotations)
  File "/home/runner/work/returns/returns/.venv/lib/python3.9/site-packages/wemake_python_styleguide/visitors/ast/complexity/annotations.py", line 67, in _check_annotations_complexity
    complexity = get_annotation_compexity(annotation)
  File "/home/runner/work/returns/returns/.venv/lib/python3.9/site-packages/wemake_python_styleguide/logic/complexity/annotations.py", line 36, in get_annotation_compexity
    annotation_node.slice.value,  # type: ignore
AttributeError: 'Tuple' object has no attribute 'value'

For more information you can see the failed pipeline here

Something weird happened, if I add --bug-report flag everything works 🤔

How is that should be

Should runs without any error with Python 3.9

System information

ubuntu-18.04

flake8 information

Contents of flake8 --bug-report:

{
  "dependencies": [],
  "platform": {
    "python_implementation": "CPython",
    "python_version": "3.9.0",
    "system": "Linux"
  },
  "plugins": [
    {
      "is_local": false,
      "plugin": "flake8-bandit",
      "version": "2.1.2"
    },
    {
      "is_local": false,
      "plugin": "flake8-broken-line",
      "version": "0.2.1"
    },
    {
      "is_local": false,
      "plugin": "flake8-bugbear",
      "version": "19.8.0"
    },
    {
      "is_local": false,
      "plugin": "flake8-comprehensions",
      "version": "3.2.3"
    },
    {
      "is_local": false,
      "plugin": "flake8-darglint",
      "version": "1.5.5"
    },
    {
      "is_local": false,
      "plugin": "flake8-debugger",
      "version": "3.2.1"
    },
    {
      "is_local": false,
      "plugin": "flake8-docstrings",
      "version": "1.5.0, pydocstyle: 5.1.1"
    },
    {
      "is_local": false,
      "plugin": "flake8-eradicate",
      "version": "0.3.0"
    },
    {
      "is_local": false,
      "plugin": "flake8-pyi",
      "version": "20.5.0"
    },
    {
      "is_local": false,
      "plugin": "flake8-pytest-style",
      "version": "1.3.0"
    },
    {
      "is_local": false,
      "plugin": "flake8-string-format",
      "version": "0.2.3"
    },
    {
      "is_local": false,
      "plugin": "flake8_commas",
      "version": "2.0.0"
    },
    {
      "is_local": false,
      "plugin": "flake8_isort",
      "version": "3.0.1"
    },
    {
      "is_local": false,
      "plugin": "flake8_quotes",
      "version": "2.1.2"
    },
    {
      "is_local": false,
      "plugin": "mccabe",
      "version": "0.6.1"
    },
    {
      "is_local": false,
      "plugin": "naming",
      "version": "0.9.1"
    },
    {
      "is_local": false,
      "plugin": "nitpick",
      "version": "0.23.0"
    },
    {
      "is_local": false,
      "plugin": "pycodestyle",
      "version": "2.6.0"
    },
    {
      "is_local": false,
      "plugin": "pyflakes",
      "version": "2.2.0"
    },
    {
      "is_local": false,
      "plugin": "rst-docstrings",
      "version": "0.0.12"
    },
    {
      "is_local": false,
      "plugin": "wemake_python_styleguide",
      "version": "0.14.1"
    }
  ],
  "version": "3.8.4"
}

Refs dry-python/returns#663

[tirkarthi]

Seems to be duplicate of #1652

[sobolevn]

Yeap.