Check bare raise occurs in except clause

pyflakes/checker.py

@@ -453,6 +453,17 @@ def getParent(self, node):
             if not hasattr(node, 'elts') and not hasattr(node, 'ctx'):
                 return node
 
+    def has_parent_type(self, node, cls):
+        """Check if node has any parent of type cls."""
+        while node:
+            try:
+                node = self.getParent(node)
+            except AttributeError:
+                return False
+            if isinstance(node, cls):
+                return True
+        return False
+
     def getCommonAncestor(self, lnode, rnode, stop):
         if stop in (lnode, rnode) or not (hasattr(lnode, 'parent') and
                                           hasattr(rnode, 'parent')):
@@ -746,7 +757,7 @@ def ignore(self, node):
 
     # "stmt" type nodes
     DELETE = PRINT = FOR = ASYNCFOR = WHILE = IF = WITH = WITHITEM = \
-        ASYNCWITH = ASYNCWITHITEM = RAISE = TRYFINALLY = EXEC = \
+        ASYNCWITH = ASYNCWITHITEM = TRYFINALLY = EXEC = \
         EXPR = ASSIGN = handleChildren
 
     PASS = ignore
@@ -1071,6 +1082,19 @@ def IMPORTFROM(self, node):
                 importation = Importation(name, node)
             self.addBinding(node, importation)
 
+    def RAISE(self, node):
+        try:
+            next(iter_child_nodes(node))
+            has_children = True
+        except StopIteration:
+            has_children = False
+
+        if not has_children:
+            if not self.has_parent_type(node, ast.ExceptHandler):
+                self.report(messages.ReraiseOutsideExcept, node)
+
+        self.handleChildren(node)
+
     def TRY(self, node):
         handler_names = []
         # List the exception handlers

pyflakes/messages.py

@@ -189,6 +189,13 @@ class ContinueInFinally(Message):
     message = '\'continue\' not supported inside \'finally\' clause'
 
 
+class ReraiseOutsideExcept(Message):
+    """
+    A bare raise used outside an except clause.
+    """
+    message = '\'raise\' not supported outside \'except\' clause'
+
+
 class DefaultExceptNotLast(Message):
     """
     Indicates an except: block as not the last exception handler.

pyflakes/test/test_other.py

@@ -885,6 +885,69 @@ def test_defaultExceptNotLast(self):
             pass
         ''', m.DefaultExceptNotLast, m.DefaultExceptNotLast)
 
+    def test_raise_name(self):
+        self.flakes('''
+        raise Exception
+        ''')
+
+    def test_raise_object(self):
+        self.flakes('''
+        raise Exception()
+        ''')
+
+    def test_raise_object_in_try(self):
+        self.flakes('''
+        try:
+            raise Exception()
+        except Exception:
+            pass
+        ''')
+
+    def test_reraise_in_except(self):
+        self.flakes('''
+        try:
+            int('x')
+        except ValueError:
+            raise
+        ''')
+
+    def test_reraise_in_except_with_if(self):
+        self.flakes('''
+        try:
+            int('x')
+        except ValueError as e:
+            if True:
+                raise
+        ''')
+
+    def test_reraise_in_try(self):
+        self.flakes('''
+        try:
+            raise
+        except Exception:
+            pass
+        ''', m.ReraiseOutsideExcept)
+
+    def test_reraise_in_finally(self):
+        self.flakes('''
+        try:
+            int('x')
+        except ValueError:
+            pass
+        finally:
+            raise
+        ''', m.ReraiseOutsideExcept)
+
+    def test_reraise_in_else(self):
+        self.flakes('''
+        try:
+            int('x')
+        except ValueError:
+            pass
+        else:
+            raise
+        ''', m.ReraiseOutsideExcept)
+
     @skipIf(version_info < (3,), "Python 3 only")
     def test_starredAssignmentNoError(self):
         """