Merge fix for issue #945.

doc/CHANGES.txt

@@ -46,6 +46,9 @@ Zope Changes
 
     Bugs fixed
     
+      - Collector #945:  Allow adding empty PythonScript instances
+        programmatically.
+
       - Updated doc/UNITTEST.txt and lib/python/Testing/README.txt to
         reflect progress made since UNITTEST.txt was originally written.
 

lib/python/RestrictedPython/RCompile.py

@@ -220,12 +220,13 @@ class RFunction(RModule):
         # Stitch the body code into the function.
         f.code.nodes = body_code.node.nodes
         f.name = self.name
-        # Look for a docstring.
-        stmt1 = f.code.nodes[0]
-        if (isinstance(stmt1, ast.Discard) and
-            isinstance(stmt1.expr, ast.Const) and
-            isinstance(stmt1.expr.value, str)):
-            f.doc = stmt1.expr.value
+        # Look for a docstring, if there are any nodes at all
+        if len(f.code.nodes) > 0:
+            stmt1 = f.code.nodes[0]
+            if (isinstance(stmt1, ast.Discard) and
+                isinstance(stmt1.expr, ast.Const) and
+                isinstance(stmt1.expr.value, str)):
+                f.doc = stmt1.expr.value
         # The caller may specify that certain variables are globals
         # so that they can be referenced before a local assignment.
         # The only known example is the variables context, container,

lib/python/RestrictedPython/tests/testRestrictions.py

@@ -13,7 +13,7 @@ import unittest
 from RestrictedPython import compile_restricted, PrintCollector
 from RestrictedPython.Eval import RestrictionCapableEval
 from RestrictedPython.tests import before_and_after, restricted_module, verify
-from RestrictedPython.RCompile import RModule
+from RestrictedPython.RCompile import RModule, RFunction
 
 try:
     __file__
@@ -437,6 +437,12 @@ class RestrictionTests(unittest.TestCase):
         co = self._compile_file("lambda.py")
         exec co in {}, {}
 
+    def checkEmpty(self):
+        rf = RFunction("", "", "issue945", "empty.py", {})
+        rf.parse()
+        rf2 = RFunction("", "# still empty\n\n# by", "issue945", "empty.py", {})
+        rf2.parse()
+
     def checkSyntaxError(self):
         err = ("def f(x, y):\n"
                "    if x, y < 2 + 1:\n"