Noissue - Improved accuracy of evaluated expressions for A103 and A207

flake8-eyeo/flake8_eyeo.py

 # This file is part of Adblock Plus <https://adblockplus.org/>,
 # Copyright (C) 2006-present eyeo GmbH
 #
 # Adblock Plus is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License version 3 as
 # published by the Free Software Foundation.
 #
 # Adblock Plus 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
@@ skipping 27 matching lines @@
     'codecs.open': 'io.open',
 }
 
 ESSENTIAL_BUILTINS = set(dir(builtins)) - {'apply', 'buffer', 'coerce',
                                            'intern', 'file'}
 
 LEAVE_BLOCK = (ast.Return, ast.Raise, ast.Continue, ast.Break)
 VOLATILE = object()
 
 
-def evaluate(node):
+def evaluate(node, namespace):
     try:
-        return eval(compile(ast.Expression(node), '', 'eval'), {})
+        return eval(compile(ast.Expression(node), '', 'eval'), namespace)
     except Exception:
         return VOLATILE
 
 
 def is_const(node):
-    return evaluate(node) is not VOLATILE
+    namespace = {'__builtins__': {'True': True, 'False': False, 'None': None}}
+    return evaluate(node, namespace) is not VOLATILE
 
 
 def get_identifier(node):
     if isinstance(node, ast.Name):
         return node.id
     if isinstance(node, ast.Attribute) and isinstance(node.value, ast.Name):
         return '{}.{}'.format(node.value.id, node.attr)
 
 
 def get_statement(node):
@@ skipping 261 matching lines @@
             left_is_target = (isinstance(target, ast.Name) and
                               isinstance(node.value.left, ast.Name) and
                               target.id == node.value.left.id)
             if left_is_target:
                 self.errors.append((node, 'A106 use augment assignment, '
                                           'e.g. x += y instead x = x + y'))
         self.generic_visit(node)
 
     def _visit_hash_keys(self, nodes, what):
         keys = []
+        namespace = collections.defaultdict(object, vars(builtins))

[Vasily Kuznetsov, 2017/10/11 19:29:02]

This is clever!

         for node in nodes:
-            key = evaluate(node)
+            key = evaluate(node, namespace)
             if key is VOLATILE:
                 continue
 
             if key in keys:
                 self.errors.append((node, 'A207 duplicate ' + what))
                 continue
 
             keys.append(key)
 
     def visit_Dict(self, node):
@@ skipping 114 matching lines @@
                     return [(pos, 'A111 redundant parenthesis for {} '
                                   'statement'.format(statement))]
 
     return []
 
 
 for checker in [check_ast, check_non_default_encoding,
                 check_quotes, check_redundant_parenthesis]:
     checker.name = 'eyeo'
     checker.version = __version__