Fix undefined name in generators in class

8c8a27b provided a partial solution for generators in the class scope,
however it did not account for generators enclosing other generators.

Author: jayvdb

pyflakes/checker.py

@@ -480,30 +480,29 @@ def handleNodeLoad(self, node):
         name = getNodeName(node)
         if not name:
             return
-        # try local scope
-        try:
-            self.scope[name].used = (self.scope, node)
-        except KeyError:
-            pass
-        else:
-            return
 
-        scopes = [scope for scope in self.scopeStack[:-1]
-                  if isinstance(scope, (FunctionScope, ModuleScope, GeneratorScope))]
-        if isinstance(self.scope, GeneratorScope) and scopes[-1] != self.scopeStack[-2]:
-            scopes.append(self.scopeStack[-2])
+        in_generators = None
+        importStarred = None
 
         # try enclosing function scopes and global scope
-        importStarred = self.scope.importStarred
-        for scope in reversed(scopes):
-            importStarred = importStarred or scope.importStarred
+        for scope in self.scopeStack[-1::-1]:
+            # only generators used in a class scope can access the names
+            # of the class. this is skipped during the first iteration
+            if in_generators is False and isinstance(scope, ClassScope):
+                continue
+
             try:
                 scope[name].used = (self.scope, node)
             except KeyError:
                 pass
             else:
                 return
 
+            importStarred = importStarred or scope.importStarred
+
+            if in_generators is not False:
+                in_generators = isinstance(scope, GeneratorScope)
+
         # look in the built-ins
         if importStarred or name in self.builtIns:
             return

pyflakes/test/test_undefined_names.py

@@ -481,8 +481,20 @@ def test_definedInGenExp(self):
         Using the loop variable of a generator expression results in no
         warnings.
         """
-        self.flakes('(a for a in %srange(10) if a)' %
-                    ('x' if version_info < (3,) else ''))
+        self.flakes('(a for a in [1, 2, 3] if a)')
+
+        self.flakes('(b for b in (a for a in [1, 2, 3] if a) if b)')
+
+    def test_undefinedInGenExpNested(self):
+        """
+        The loop variables of generator expressions nested together are
+        not defined in the other generator.
+        """
+        self.flakes('(b for b in (a for a in [1, 2, 3] if b) if b)',
+                    m.UndefinedName)
+
+        self.flakes('(b for b in (a for a in [1, 2, 3] if a) if a)',
+                    m.UndefinedName)
 
     def test_undefinedWithErrorHandler(self):
         """
@@ -537,6 +549,15 @@ class A:
                 Y = {x:x for x in T}
             ''')
 
+    def test_definedInClassNested(self):
+        """Defined name for nested generator expressions in a class."""
+        self.flakes('''
+        class A:
+            T = range(10)
+
+            Z = (x for x in (a for a in T))
+        ''')
+
     def test_undefinedInLoop(self):
         """
         The loop variable is defined after the expression is computed.