Fix ci: pin linux, pin flake8, ignore type error, fix mypy

.github/workflows/CI.yaml

@@ -10,7 +10,7 @@ jobs:
     # https://github.com/actions/python-versions/blob/main/versions-manifest.json
     strategy:
       matrix:
-        os: [macos-latest, ubuntu-latest]
+        os: [macos-latest, ubuntu-20.04]
         python-version: [3.6, 3.7, 3.8, pypy-3.7]
     steps:
       - uses: actions/checkout@v2
@@ -21,7 +21,7 @@ jobs:
       - name: Install Requirements
         run: |
           python -m pip install --upgrade pip
-          pip install flake8 pylint pytest
+          pip install flake8==5.0.4 pylint pytest
           pip install -r requirements.txt
           pip install -r test/requirements.txt
           python setup.py install

mypy.ini

@@ -1,5 +1,4 @@
 [mypy]
 # follow_imports = False
 ignore_missing_imports = True
-show_none_errors = True
 strict_optional = True

stone/frontend/ir_generator.py

@@ -9,7 +9,7 @@
 try:
     from inspect import getfullargspec as get_args
 except ImportError:
-    from inspect import getargspec as get_args
+    from inspect import getargspec as get_args  # type: ignore
 
 _MYPY = False
 if _MYPY:

test/test_python_gen.py

@@ -1245,8 +1245,8 @@ def test_struct_equality_with_value(self):
         self.assertNotEqual(s, s_unequal)
 
     def test_struct_equality_with_different_types(self):
-        """Structs of different types that do not have an inheritance relationship are not considered
-        equal to each other."""
+        """Structs of different types that do not have an inheritance relationship are not
+        considered equal to each other."""
         s = self.decode(bv.Struct(self.ns.S), json.dumps({'f': 'F'}))
         t = self.decode(bv.Struct(self.ns.T), json.dumps({'f': 'F'}))
         self.assertNotEqual(s, t)

tox.ini

@@ -38,7 +38,7 @@ commands =
     pylint --rcfile=.pylintrc setup.py example stone test
 
 deps =
-    flake8
+    flake8<6
     pylint
     # This probably breaks on Windows. See
     # <https://github.com/tox-dev/tox/issues/384>.