Remove Python Compatibility Warnings (#182)

- The world has move to Python 3
  - If people need these checks they can pin to 21.4.3

Tests: Ensure all remaining tests still pass

Fixes #177

Author: cooperlees

Diff for: README.rst

@@ -131,45 +131,6 @@ Either assert for a more specific exception (builtin or custom), use
 data available in ``ex``.
 
 
-Python 3 compatibility warnings
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-These have higher risk of false positives but discover regressions that
-are dangerous to slip through when test coverage is not great. Let me
-know if a popular library is triggering any of the following warnings
-for valid code.
-
-**B301**: Python 3 does not include ``.iter*`` methods on dictionaries.
-The default behavior is to return iterables. Simply remove the ``iter``
-prefix from the method.  For Python 2 compatibility, also prefer the
-Python 3 equivalent if you expect that the size of the dict to be small
-and bounded. The performance regression on Python 2 will be negligible
-and the code is going to be the clearest.  Alternatively, use
-``six.iter*`` or ``future.utils.iter*``.
-
-**B302**: Python 3 does not include ``.view*`` methods on dictionaries.
-The default behavior is to return viewables. Simply remove the ``view``
-prefix from the method.  For Python 2 compatibility, also prefer the
-Python 3 equivalent if you expect that the size of the dict to be small
-and bounded. The performance regression on Python 2 will be negligible
-and the code is going to be the clearest.  Alternatively, use
-``six.view*`` or ``future.utils.view*``.
-
-**B303**: The ``__metaclass__`` attribute on a class definition does
-nothing on Python 3. Use ``class MyClass(BaseClass, metaclass=...)``.
-For Python 2 compatibility, use ``six.add_metaclass``.
-
-**B304**: ``sys.maxint`` is not a thing on Python 3. Use
-``sys.maxsize``.
-
-**B305**: ``.next()`` is not a thing on Python 3. Use the ``next()``
-builtin. For Python 2 compatibility, use ``six.next()``.
-
-**B306**: ``BaseException.message`` has been deprecated as of Python 2.6
-and is removed in Python 3. Use ``str(e)`` to access the user-readable
-message. Use ``e.args`` to access arguments passed to the exception.
-
-
 Opinionated warnings
 ~~~~~~~~~~~~~~~~~~~~
 

Diff for: bugbear.py

@@ -226,14 +226,7 @@ def visit_UAdd(self, node):
 
     def visit_Call(self, node):
         if isinstance(node.func, ast.Attribute):
-            for bug in (B301, B302, B305):
-                if node.func.attr in bug.methods:
-                    call_path = ".".join(self.compose_call_path(node.func.value))
-                    if call_path not in bug.valid_paths:
-                        self.errors.append(bug(node.lineno, node.col_offset))
-                    break
-            else:
-                self.check_for_b005(node)
+            self.check_for_b005(node)
         else:
             with suppress(AttributeError, IndexError):
                 if (
@@ -258,25 +251,8 @@ def visit_Call(self, node):
 
         self.generic_visit(node)
 
-    def visit_Attribute(self, node):
-        call_path = list(self.compose_call_path(node))
-        if ".".join(call_path) == "sys.maxint":
-            self.errors.append(B304(node.lineno, node.col_offset))
-        elif len(call_path) == 2 and call_path[1] == "message":
-            name = call_path[0]
-            for elem in reversed(self.node_stack[:-1]):
-                if isinstance(elem, ast.ExceptHandler) and elem.name == name:
-                    self.errors.append(B306(node.lineno, node.col_offset))
-                    break
-
     def visit_Assign(self, node):
-        if isinstance(self.node_stack[-2], ast.ClassDef):
-            # note: by hasattr below we're ignoring starred arguments, slices
-            # and tuples for simplicity.
-            assign_targets = {t.id for t in node.targets if hasattr(t, "id")}
-            if "__metaclass__" in assign_targets:
-                self.errors.append(B303(node.lineno, node.col_offset))
-        elif len(node.targets) == 1:
+        if len(node.targets) == 1:
             t = node.targets[0]
             if isinstance(t, ast.Attribute) and isinstance(t.value, ast.Name):
                 if (t.value.id, t.attr) == ("os", "environ"):
@@ -771,60 +747,6 @@ def visit(self, node):
     )
 )
 
-# Those could be false positives but it's more dangerous to let them slip
-# through if they're not.
-B301 = Error(
-    message=(
-        "B301 Python 3 does not include `.iter*` methods on dictionaries. "
-        "Remove the `iter` prefix from the method name. For Python 2 "
-        "compatibility, prefer the Python 3 equivalent unless you expect "
-        "the size of the container to be large or unbounded. Then use "
-        "`six.iter*` or `future.utils.iter*`."
-    )
-)
-B301.methods = {"iterkeys", "itervalues", "iteritems", "iterlists"}
-B301.valid_paths = {"six", "future.utils", "builtins"}
-
-B302 = Error(
-    message=(
-        "B302 Python 3 does not include `.view*` methods on dictionaries. "
-        "Remove the `view` prefix from the method name. For Python 2 "
-        "compatibility, prefer the Python 3 equivalent unless you expect "
-        "the size of the container to be large or unbounded. Then use "
-        "`six.view*` or `future.utils.view*`."
-    )
-)
-B302.methods = {"viewkeys", "viewvalues", "viewitems", "viewlists"}
-B302.valid_paths = {"six", "future.utils", "builtins"}
-
-B303 = Error(
-    message=(
-        "B303 `__metaclass__` does nothing on Python 3. Use "
-        "`class MyClass(BaseClass, metaclass=...)`. For Python 2 "
-        "compatibility, use `six.add_metaclass`."
-    )
-)
-
-B304 = Error(message="B304 `sys.maxint` is not a thing on Python 3. Use `sys.maxsize`.")
-
-B305 = Error(
-    message=(
-        "B305 `.next()` is not a thing on Python 3. Use the `next()` "
-        "builtin. For Python 2 compatibility, use `six.next()`."
-    )
-)
-B305.methods = {"next"}
-B305.valid_paths = {"six", "future.utils", "builtins"}
-
-B306 = Error(
-    message=(
-        "B306 `BaseException.message` has been deprecated as of Python "
-        "2.6 and is removed in Python 3. Use `str(e)` to access the "
-        "user-readable message. Use `e.args` to access arguments passed "
-        "to the exception."
-    )
-)
-
 # Warnings disabled by default.
 B901 = Error(
     message=(

Diff for: tests/b301_b302_b305.py

@@ -28,12 +28,6 @@
     B015,
     B016,
     B017,
-    B301,
-    B302,
-    B303,
-    B304,
-    B305,
-    B306,
     B901,
     B902,
     B903,
@@ -213,38 +207,6 @@ def test_b017(self):
         expected = self.errors(B017(22, 8))
         self.assertEqual(errors, expected)
 
-    def test_b301_b302_b305(self):
-        filename = Path(__file__).absolute().parent / "b301_b302_b305.py"
-        bbc = BugBearChecker(filename=str(filename))
-        errors = list(bbc.run())
-        self.assertEqual(
-            errors,
-            self.errors(
-                B301(39, 4),
-                B301(40, 4),
-                B301(41, 4),
-                B301(42, 4),
-                B302(43, 4),
-                B302(44, 4),
-                B302(45, 4),
-                B302(46, 4),
-                B305(47, 4),
-                B305(48, 4),
-            ),
-        )
-
-    def test_b303_b304(self):
-        filename = Path(__file__).absolute().parent / "b303_b304.py"
-        bbc = BugBearChecker(filename=str(filename))
-        errors = list(bbc.run())
-        self.assertEqual(errors, self.errors(B303(25, 4), B304(46, 4)))
-
-    def test_b306(self):
-        filename = Path(__file__).absolute().parent / "b306.py"
-        bbc = BugBearChecker(filename=str(filename))
-        errors = list(bbc.run())
-        self.assertEqual(errors, self.errors(B306(9, 10)))
-
     def test_b901(self):
         filename = Path(__file__).absolute().parent / "b901.py"
         bbc = BugBearChecker(filename=str(filename))