Extend the cases where 'undefined-variable' and 'used-before-assignment' can be detected. Closes issue #291.

6 files changed, 89 insertions, 5 deletions

diff --git a/ChangeLog b/ChangeLog
index 5ae6341..8ef316f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -95,6 +95,9 @@ ChangeLog for Pylint
       string contains mixed attribute access arguments and manual
       fields. Closes issue #322.
 
+    * Extend the cases where 'undefined-variable' and 'used-before-assignment'
+      can be detected. Closes issue #291.
+
 
 2014-07-26  --  1.3.0
 
diff --git a/checkers/variables.py b/checkers/variables.py
index 6a26f5a..12a26ad 100644
--- a/checkers/variables.py
+++ b/checkers/variables.py
@@ -37,6 +37,7 @@ import six
 
 SPECIAL_OBJ = re.compile("^_{2}[a-z]+_{2}$")
 
+PY3K = sys.version_info >= (3, 0)
 
 def in_for_else_branch(parent, stmt):
     """Returns True if stmt in inside the else branch for a parent For stmt."""
@@ -731,9 +732,8 @@ builtins. Remember that you should avoid to define new builtins when possible.'
                 # class A:
                 #    b = 1
                 #    c = lambda b=b: b * b
-                class_assignment = (isinstance(frame, astroid.Class) and
-                                    name in frame.locals)
-                if not class_assignment:
+                if not (isinstance(frame, astroid.Class) and
+                            name in frame.locals):
                     continue
             # the name has already been consumed, only check it's not a loop
             # variable used outside the loop
@@ -773,10 +773,35 @@ builtins. Remember that you should avoid to define new builtins when possible.'
                             maybee0601 = not any(isinstance(child, astroid.Nonlocal)
                                                  and name in child.names
                                                  for child in defframe.get_children())
+
+                # Handle a couple of class scoping issues.
+                annotation_return = False
+                # The class reuses itself in the class scope.
+                recursive_klass = (frame is defframe and
+                                       defframe.parent_of(node) and
+                                       isinstance(defframe, astroid.Class) and
+                                       node.name == defframe.name)
                 if (self._to_consume[-1][-1] == 'lambda' and
                         isinstance(frame, astroid.Class)
                         and name in frame.locals):
                     maybee0601 = True
+                elif (isinstance(defframe, astroid.Class) and
+                          isinstance(frame, astroid.Function)):
+                    # Special rule for function return annotations,
+                    # which uses the same name as the class where
+                    # the function lives.
+                    if (PY3K and node is frame.returns and
+                            defframe.parent_of(frame.returns)):
+                        maybee0601 = annotation_return = True
+
+                    if (maybee0601 and defframe.name in defframe.locals and
+                            defframe.locals[name][0].lineno < frame.lineno):
+                        # Detect class assignments with the same
+                        # name as the class. In this case, no warning
+                        # should be raised.
+                        maybee0601 = False
+                elif recursive_klass:
+                    maybee0601 = True
                 else:
                     maybee0601 = maybee0601 and stmt.fromlineno <= defstmt.fromlineno
 
@@ -785,8 +810,11 @@ builtins. Remember that you should avoid to define new builtins when possible.'
                         and not are_exclusive(stmt, defstmt, ('NameError',
                                                               'Exception',
                                                               'BaseException'))):
-                    if defstmt is stmt and isinstance(node, (astroid.DelName,
-                                                             astroid.AssName)):
+                    if recursive_klass or (defstmt is stmt and
+                                              isinstance(node, (astroid.DelName,
+                                                                    astroid.AssName))):
+                        self.add_message('undefined-variable', args=name, node=node)
+                    elif annotation_return:
                         self.add_message('undefined-variable', args=name, node=node)
                     elif self._to_consume[-1][-1] != 'lambda':
                         # E0601 may *not* occurs in lambda scope.
diff --git a/test/functional/undefined_variable.py b/test/functional/undefined_variable.py
index 003708c..0b5f7aa 100644
--- a/test/functional/undefined_variable.py
+++ b/test/functional/undefined_variable.py
@@ -109,6 +109,18 @@ class TestClass(Ancestor):  # [used-before-assignment]
             """ no op """
         return MissingAncestor1
 
+class Self(object):
+    """ Detect when using the same name inside the class scope. """
+    obj = Self # [undefined-variable]
+
+class Self1(object):
+    """ No error should be raised here. """
+
+    def test(self):
+        """ empty """
+        return Self1
+
+
 class Ancestor(object):
     """ No op """
 
diff --git a/test/functional/undefined_variable.txt b/test/functional/undefined_variable.txt
index 5695be1..497f320 100644
--- a/test/functional/undefined_variable.txt
+++ b/test/functional/undefined_variable.txt
@@ -15,3 +15,4 @@ used-before-assignment:86:test_arguments:Using variable 'TestClass' before assig
 used-before-assignment:90:TestClass:Using variable 'Ancestor' before assignment
 used-before-assignment:93:TestClass.MissingAncestor:Using variable 'Ancestor1' before assignment
 used-before-assignment:100:TestClass.test1.UsingBeforeDefinition:Using variable 'Empty' before assignment
+undefined-variable:114:Self:Undefined variable 'Self'
\ No newline at end of file
diff --git a/test/functional/undefined_variable_py30.py b/test/functional/undefined_variable_py30.py
new file mode 100644
index 0000000..74e65a6
--- /dev/null
+++ b/test/functional/undefined_variable_py30.py
@@ -0,0 +1,37 @@
+"""Test warnings about access to undefined variables
+for various Python 3 constructs. """
+# pylint: disable=too-few-public-methods, no-init, no-self-use
+
+class Undefined:
+    """ test various annotation problems. """
+
+    def test(self)->Undefined: # [undefined-variable]
+        """ used Undefined, which is Undefined in this scope. """
+
+    Undefined = True
+
+    def test1(self)->Undefined:
+        """ This Undefined exists at local scope. """
+
+    def test2(self):
+        """ This should not emit. """
+        def func()->Undefined:
+            """ empty """
+            return
+        return func
+
+
+class Undefined1:
+    """ Other annotation problems. """
+
+    Undef = 42
+    ABC = 42
+
+    class InnerScope:
+        """ Test inner scope definition. """
+
+        def test_undefined(self)->Undef: # [undefined-variable]
+            """ Looking at a higher scope is impossible. """
+
+        def test1(self)->ABC: # [undefined-variable]
+            """ Triggers undefined-variable. """
diff --git a/test/functional/undefined_variable_py30.txt b/test/functional/undefined_variable_py30.txt
new file mode 100644
index 0000000..30004bd
--- /dev/null
+++ b/test/functional/undefined_variable_py30.txt
@@ -0,0 +1,3 @@
+undefined-variable:8:Undefined.test:Undefined variable 'Undefined'

+undefined-variable:33:Undefined1.InnerScope.test_undefined:Undefined variable 'Undef'

+undefined-variable:36:Undefined1.InnerScope.test1:Undefined variable 'ABC'
\ No newline at end of file