pylint: upgrade to 1.4.0

third_party/pylint/checkers/python3.py

+# Copyright 2014 Google Inc.
+# This program is free software; you can redistribute it and/or modify it under
+# the terms of the GNU General Public License as published by the Free Software
+# Foundation; either version 2 of the License, or (at your option) any later
+# version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+# FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program; if not, write to the Free Software Foundation, Inc.,
+# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+"""Check Python 2 code for Python 2/3 source-compatible issues."""
+from __future__ import absolute_import
+
+import re
+import tokenize
+
+import astroid
+from pylint import checkers, interfaces
+from pylint.utils import WarningScope
+from pylint.checkers import utils
+
+
+_ZERO = re.compile("^0+$")
+
+def _is_old_octal(literal):
+    if _ZERO.match(literal):
+        return False
+    if re.match('0\d+', literal):
+        try:
+            int(literal, 8)
+        except ValueError:
+            return False
+        return True
+
+def _check_dict_node(node):
+    inferred_types = set()
+    try:
+        inferred = node.infer()
+        for inferred_node in inferred:
+            inferred_types.add(inferred_node)
+    except (astroid.InferenceError, astroid.UnresolvableName):
+        pass
+    return (not inferred_types
+            or any(isinstance(x, astroid.Dict) for x in inferred_types))
+
+
+class Python3Checker(checkers.BaseChecker):
+
+    __implements__ = interfaces.IAstroidChecker
+    enabled = False
+    name = 'python3'
+
+    msgs = {
+        # Errors for what will syntactically break in Python 3, warnings for
+        # everything else.
+        'E1601': ('print statement used',
+                  'print-statement',
+                  'Used when a print statement is used '
+                  '(`print` is a function in Python 3)',
+                  {'maxversion': (3, 0)}),
+        'E1602': ('Parameter unpacking specified',
+                  'parameter-unpacking',
+                  'Used when parameter unpacking is specified for a function'
+                  "(Python 3 doesn't allow it)",
+                  {'maxversion': (3, 0)}),
+        'E1603': ('Implicit unpacking of exceptions is not supported '
+                  'in Python 3',
+                  'unpacking-in-except',
+                  'Python3 will not allow implicit unpacking of '
+                  'exceptions in except clauses. '
+                  'See http://www.python.org/dev/peps/pep-3110/',
+                  {'maxversion': (3, 0),
+                   'old_names': [('W0712', 'unpacking-in-except')]}),
+        'E1604': ('Use raise ErrorClass(args) instead of '
+                  'raise ErrorClass, args.',
+                  'old-raise-syntax',
+                  "Used when the alternate raise syntax "
+                  "'raise foo, bar' is used "
+                  "instead of 'raise foo(bar)'.",
+                  {'maxversion': (3, 0),
+                   'old_names': [('W0121', 'old-raise-syntax')]}),
+        'E1605': ('Use of the `` operator',
+                  'backtick',
+                  'Used when the deprecated "``" (backtick) operator is used '
+                  'instead  of the str() function.',
+                  {'scope': WarningScope.NODE,
+                   'maxversion': (3, 0),
+                   'old_names': [('W0333', 'backtick')]}),
+        'W1601': ('apply built-in referenced',
+                  'apply-builtin',
+                  'Used when the apply built-in function is referenced '
+                  '(missing from Python 3)',
+                  {'maxversion': (3, 0)}),
+        'W1602': ('basestring built-in referenced',
+                  'basestring-builtin',
+                  'Used when the basestring built-in function is referenced '
+                  '(missing from Python 3)',
+                  {'maxversion': (3, 0)}),
+        'W1603': ('buffer built-in referenced',
+                  'buffer-builtin',
+                  'Used when the buffer built-in function is referenced '
+                  '(missing from Python 3)',
+                  {'maxversion': (3, 0)}),
+        'W1604': ('cmp built-in referenced',
+                  'cmp-builtin',
+                  'Used when the cmp built-in function is referenced '
+                  '(missing from Python 3)',
+                  {'maxversion': (3, 0)}),
+        'W1605': ('coerce built-in referenced',
+                  'coerce-builtin',
+                  'Used when the coerce built-in function is referenced '
+                  '(missing from Python 3)',
+                  {'maxversion': (3, 0)}),
+        'W1606': ('execfile built-in referenced',
+                  'execfile-builtin',
+                  'Used when the execfile built-in function is referenced '
+                  '(missing from Python 3)',
+                  {'maxversion': (3, 0)}),
+        'W1607': ('file built-in referenced',
+                  'file-builtin',
+                  'Used when the file built-in function is referenced '
+                  '(missing from Python 3)',
+                  {'maxversion': (3, 0)}),
+        'W1608': ('long built-in referenced',
+                  'long-builtin',
+                  'Used when the long built-in function is referenced '
+                  '(missing from Python 3)',
+                  {'maxversion': (3, 0)}),
+        'W1609': ('raw_input built-in referenced',
+                  'raw_input-builtin',
+                  'Used when the raw_input built-in function is referenced '
+                  '(missing from Python 3)',
+                  {'maxversion': (3, 0)}),
+        'W1610': ('reduce built-in referenced',
+                  'reduce-builtin',
+                  'Used when the reduce built-in function is referenced '
+                  '(missing from Python 3)',
+                  {'maxversion': (3, 0)}),
+        'W1611': ('StandardError built-in referenced',
+                  'standarderror-builtin',
+                  'Used when the StandardError built-in function is referenced '
+                  '(missing from Python 3)',
+                  {'maxversion': (3, 0)}),
+        'W1612': ('unicode built-in referenced',
+                  'unicode-builtin',
+                  'Used when the unicode built-in function is referenced '
+                  '(missing from Python 3)',
+                  {'maxversion': (3, 0)}),
+        'W1613': ('xrange built-in referenced',
+                  'xrange-builtin',
+                  'Used when the xrange built-in function is referenced '
+                  '(missing from Python 3)',
+                  {'maxversion': (3, 0)}),
+        'W1614': ('__coerce__ method defined',
+                  'coerce-method',
+                  'Used when a __coerce__ method is defined '
+                  '(method is not used by Python 3)',
+                  {'maxversion': (3, 0)}),
+        'W1615': ('__delslice__ method defined',
+                  'delslice-method',
+                  'Used when a __delslice__ method is defined '
+                  '(method is not used by Python 3)',
+                  {'maxversion': (3, 0)}),
+        'W1616': ('__getslice__ method defined',
+                  'getslice-method',
+                  'Used when a __getslice__ method is defined '
+                  '(method is not used by Python 3)',
+                  {'maxversion': (3, 0)}),
+        'W1617': ('__setslice__ method defined',
+                  'setslice-method',
+                  'Used when a __setslice__ method is defined '
+                  '(method is not used by Python 3)',
+                  {'maxversion': (3, 0)}),
+        'W1618': ('import missing `from __future__ import absolute_import`',
+                  'no-absolute-import',
+                  'Used when an import is not accompanied by '
+                  '`from __future__ import absolute_import`'
+                  ' (default behaviour in Python 3)',
+                  {'maxversion': (3, 0)}),
+        'W1619': ('division w/o __future__ statement',
+                  'old-division',
+                  'Used for non-floor division w/o a float literal or '
+                  '``from __future__ import division``'
+                  '(Python 3 returns a float for int division unconditionally)',
+                  {'maxversion': (3, 0)}),
+        'W1620': ('Calling a dict.iter*() method',
+                  'dict-iter-method',
+                  'Used for calls to dict.iterkeys(), itervalues() or iteritems() '
+                  '(Python 3 lacks these methods)',
+                  {'maxversion': (3, 0)}),
+        'W1621': ('Calling a dict.view*() method',
+                  'dict-view-method',
+                  'Used for calls to dict.viewkeys(), viewvalues() or viewitems() '
+                  '(Python 3 lacks these methods)',
+                  {'maxversion': (3, 0)}),
+        'W1622': ('Called a next() method on an object',
+                  'next-method-called',
+                  "Used when an object's next() method is called "
+                  '(Python 3 uses the next() built-in function)',
+                  {'maxversion': (3, 0)}),
+        'W1623': ("Assigning to a class' __metaclass__ attribute",
+                  'metaclass-assignment',
+                  "Used when a metaclass is specified by assigning to __metaclass__ "
+                  '(Python 3 specifies the metaclass as a class statement argument)',
+                  {'maxversion': (3, 0)}),
+        'W1624': ('Indexing exceptions will not work on Python 3',
+                  'indexing-exception',
+                  'Indexing exceptions will not work on Python 3. Use '
+                  '`exception.args[index]` instead.',
+                  {'maxversion': (3, 0),
+                   'old_names': [('W0713', 'indexing-exception')]}),
+        'W1625': ('Raising a string exception',
+                  'raising-string',
+                  'Used when a string exception is raised. This will not '
+                  'work on Python 3.',
+                  {'maxversion': (3, 0),
+                   'old_names': [('W0701', 'raising-string')]}),
+        'W1626': ('reload built-in referenced',
+                  'reload-builtin',
+                  'Used when the reload built-in function is referenced '
+                  '(missing from Python 3). You can use instead imp.reload '
+                  'or importlib.reload.',
+                  {'maxversion': (3, 0)}),
+        'W1627': ('__oct__ method defined',
+                  'oct-method',
+                  'Used when a __oct__ method is defined '
+                  '(method is not used by Python 3)',
+                  {'maxversion': (3, 0)}),
+        'W1628': ('__hex__ method defined',
+                  'hex-method',
+                  'Used when a __hex__ method is defined '
+                  '(method is not used by Python 3)',
+                  {'maxversion': (3, 0)}),
+        'W1629': ('__nonzero__ method defined',
+                  'nonzero-method',
+                  'Used when a __nonzero__ method is defined '
+                  '(method is not used by Python 3)',
+                  {'maxversion': (3, 0)}),
+        'W1630': ('__cmp__ method defined',
+                  'cmp-method',
+                  'Used when a __cmp__ method is defined '
+                  '(method is not used by Python 3)',
+                  {'maxversion': (3, 0)}),
+        'W1631': ('map is used as implicitly evaluated call',
+                  'implicit-map-evaluation',
+                  'Used when the map builtin is used as implicitly '
+                  'evaluated call, as in "map(func, args)" on a single line. '
+                  'This behaviour will not work in Python 3, where '
+                  'map is a generator and must be evaluated. '
+                  'Prefer a for-loop as alternative.',
+                  {'maxversion': (3, 0)}),
+    }
+
+    _missing_builtins = frozenset([
+        'apply',
+        'basestring',
+        'buffer',
+        'cmp',
+        'coerce',
+        'execfile',
+        'file',
+        'long',
+        'raw_input',
+        'reduce',
+        'StandardError',
+        'unicode',
+        'xrange',
+        'reload',
+    ])
+
+    _unused_magic_methods = frozenset([
+        '__coerce__',
+        '__delslice__',
+        '__getslice__',
+        '__setslice__',
+        '__oct__',
+        '__hex__',
+        '__nonzero__',
+        '__cmp__',
+    ])
+
+    def __init__(self, *args, **kwargs):
+        self._future_division = False
+        self._future_absolute_import = False
+        super(Python3Checker, self).__init__(*args, **kwargs)
+
+    def visit_function(self, node):
+        if node.is_method() and node.name in self._unused_magic_methods:
+            method_name = node.name
+            if node.name.startswith('__'):
+                method_name = node.name[2:-2]
+            self.add_message(method_name + '-method', node=node)
+
+    @utils.check_messages('parameter-unpacking')
+    def visit_arguments(self, node):
+        for arg in node.args:
+            if isinstance(arg, astroid.Tuple):
+                self.add_message('parameter-unpacking', node=arg)
+
+    @utils.check_messages('implicit-map-evaluation')
+    def visit_discard(self, node):
+        if (isinstance(node.value, astroid.CallFunc) and
+                isinstance(node.value.func, astroid.Name) and
+                node.value.func.name == 'map'):
+            module = node.value.func.lookup('map')[0]
+            if getattr(module, 'name', None) == '__builtin__':
+                self.add_message('implicit-map-evaluation', node=node)
+
+    def visit_name(self, node):
+        """Detect when a built-in that is missing in Python 3 is referenced."""
+        found_node = node.lookup(node.name)[0]
+        if getattr(found_node, 'name', None) == '__builtin__':
+            if node.name in self._missing_builtins:
+                message = node.name.lower() + '-builtin'
+                self.add_message(message, node=node)
+
+    @utils.check_messages('print-statement')
+    def visit_print(self, node):
+        self.add_message('print-statement', node=node)
+
+    @utils.check_messages('no-absolute-import')
+    def visit_from(self, node):
+        if node.modname == '__future__':
+            for name, _ in node.names:
+                if name == 'division':
+                    self._future_division = True
+                elif name == 'absolute_import':
+                    self._future_absolute_import = True
+        elif not self._future_absolute_import:
+            self.add_message('no-absolute-import', node=node)
+
+    @utils.check_messages('no-absolute-import')
+    def visit_import(self, node):
+        if not self._future_absolute_import:
+            self.add_message('no-absolute-import', node=node)
+
+    @utils.check_messages('metaclass-assignment')
+    def visit_class(self, node):
+        if '__metaclass__' in node.locals:
+            self.add_message('metaclass-assignment', node=node)
+
+    @utils.check_messages('old-division')
+    def visit_binop(self, node):
+        if not self._future_division and node.op == '/':
+            for arg in (node.left, node.right):
+                if isinstance(arg, astroid.Const) and isinstance(arg.value, float):
+                    break
+            else:
+                self.add_message('old-division', node=node)
+
+    @utils.check_messages('next-method-called',
+                          'dict-iter-method',
+                          'dict-view-method')
+    def visit_callfunc(self, node):
+        if not isinstance(node.func, astroid.Getattr):
+            return
+        if any([node.args, node.starargs, node.kwargs]):
+            return
+        if node.func.attrname == 'next':
+            self.add_message('next-method-called', node=node)
+        else:
+            if _check_dict_node(node.func.expr):
+                if node.func.attrname in ('iterkeys', 'itervalues', 'iteritems'):
+                    self.add_message('dict-iter-method', node=node)
+                elif node.func.attrname in ('viewkeys', 'viewvalues', 'viewitems'):
+                    self.add_message('dict-view-method', node=node)
+
+    @utils.check_messages('indexing-exception')
+    def visit_subscript(self, node):
+        """ Look for indexing exceptions. """
+        try:
+            for infered in node.value.infer():
+                if not isinstance(infered, astroid.Instance):
+                    continue
+                if utils.inherit_from_std_ex(infered):
+                    self.add_message('indexing-exception', node=node)
+        except astroid.InferenceError:
+            return
+
+    @utils.check_messages('unpacking-in-except')
+    def visit_excepthandler(self, node):
+        """Visit an except handler block and check for exception unpacking."""
+        if isinstance(node.name, (astroid.Tuple, astroid.List)):
+            self.add_message('unpacking-in-except', node=node)
+
+    @utils.check_messages('backtick')
+    def visit_backquote(self, node):
+        self.add_message('backtick', node=node)
+
+    @utils.check_messages('raising-string', 'old-raise-syntax')
+    def visit_raise(self, node):
+        """Visit a raise statement and check for raising
+        strings or old-raise-syntax.
+        """
+        if (node.exc is not None and
+                node.inst is not None and
+                node.tback is None):
+            self.add_message('old-raise-syntax', node=node)
+
+        # Ignore empty raise.
+        if node.exc is None:
+            return
+        expr = node.exc
+        if self._check_raise_value(node, expr):
+            return
+        else:
+            try:
+                value = next(astroid.unpack_infer(expr))
+            except astroid.InferenceError:
+                return
+            self._check_raise_value(node, value)
+
+    def _check_raise_value(self, node, expr):
+        if isinstance(expr, astroid.Const):
+            value = expr.value
+            if isinstance(value, str):
+                self.add_message('raising-string', node=node)
+                return True
+
+
+class Python3TokenChecker(checkers.BaseTokenChecker):
+    __implements__ = interfaces.ITokenChecker
+    name = 'python3'
+    enabled = False
+
+    msgs = {
+        'E1606': ('Use of long suffix',
+                  'long-suffix',
+                  'Used when "l" or "L" is used to mark a long integer. '
+                  'This will not work in Python 3, since `int` and `long` '
+                  'types have merged.',
+                  {'maxversion': (3, 0)}),
+        'E1607': ('Use of the <> operator',
+                  'old-ne-operator',
+                  'Used when the deprecated "<>" operator is used instead '
+                  'of "!=". This is removed in Python 3.',
+                  {'maxversion': (3, 0),
+                   'old_names': [('W0331', 'old-ne-operator')]}),
+        'E1608': ('Use of old octal literal',
+                  'old-octal-literal',
+                  'Usen when encountering the old octal syntax, '
+                  'removed in Python 3. To use the new syntax, '
+                  'prepend 0o on the number.',
+                  {'maxversion': (3, 0)}),
+    }
+
+    def process_tokens(self, tokens):
+        for idx, (tok_type, token, start, _, _) in enumerate(tokens):
+            if tok_type == tokenize.NUMBER:
+                if token.lower().endswith('l'):
+                    # This has a different semantic than lowercase-l-suffix.
+                    self.add_message('long-suffix', line=start[0])
+                elif _is_old_octal(token):
+                    self.add_message('old-octal-literal', line=start[0])
+            if tokens[idx][1] == '<>':
+                self.add_message('old-ne-operator', line=tokens[idx][2][0])
+
+
+def register(linter):
+    linter.register_checker(Python3Checker(linter))
+    linter.register_checker(Python3TokenChecker(linter))