closes #74748: getitem protocal should return Const node, not the bare python value

This one is cute. It's a fix for a crash that occurs on code like

 "any string literal"[0].upper()

due to the fact that the extracted string literal is not properly wrapped,
but returned as a naked string object.

(patch by google)

3 files changed, 11 insertions, 2 deletions

diff --git a/ChangeLog b/ChangeLog
index 36d8f72e..8b9aa2a0 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -2,7 +2,12 @@ Change log for the astng package
 ================================
 
 --
-    * #74746: should return empty module when __main__ is imported (patch by google)
+    * #74746: should return empty module when __main__ is imported (patch by
+      google)
+
+    * #74748: getitem protocal return constant value instead of a Const node
+      (patch by google)
+
 
 2011-07-18  --  0.22.0
     * added column offset information on nodes (patch by fawce)
diff --git a/node_classes.py b/node_classes.py
index 4dd8520c..607ad907 100644
--- a/node_classes.py
+++ b/node_classes.py
@@ -435,7 +435,7 @@ class Const(NodeNG, Instance):
 
     def getitem(self, index, context=None):
         if isinstance(self.value, basestring):
-            return self.value[index]
+            return Const(self.value[index])
         raise TypeError('%r (value=%s)' % (self, self.value))
 
     def has_dynamic_getattr(self):
diff --git a/test/unittest_inference.py b/test/unittest_inference.py
index a1483a18..5eca958f 100644
--- a/test/unittest_inference.py
+++ b/test/unittest_inference.py
@@ -397,6 +397,7 @@ l = [1]
 t = (2,)
 d = {}
 s = ''
+s2 = '_'
         '''
         astng = builder.string_build(code, __name__, __file__)
         n = astng['l']
@@ -427,6 +428,9 @@ s = ''
         self.assertIsInstance(infered, Instance)
         self.failUnlessEqual(infered.name, 'str')
         self.failUnless('lower' in infered._proxied.locals)
+        n = astng['s2']
+        infered = n.infer().next()
+        self.failUnlessEqual(infered.getitem(0).value, '_')
 
     def test_unicode_type(self):
         if sys.version_info >= (3, 0):