Merged revisions 81823,81835 via svnmerge from
svn+ssh://pythondev@svn.python.org/python/branches/py3k

................
  r81823 | benjamin.peterson | 2010-06-07 17:31:26 -0500 (Mon, 07 Jun 2010) | 9 lines

  Merged revisions 81820 via svnmerge from
  svn+ssh://pythondev@svn.python.org/python/trunk

  ........
    r81820 | benjamin.peterson | 2010-06-07 17:23:23 -0500 (Mon, 07 Jun 2010) | 1 line

    correctly overflow when indexes are too large
  ........
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  r81835 | benjamin.peterson | 2010-06-08 09:57:22 -0500 (Tue, 08 Jun 2010) | 9 lines

  Merged revisions 81834 via svnmerge from
  svn+ssh://pythondev@svn.python.org/python/trunk

  ........
    r81834 | benjamin.peterson | 2010-06-08 09:53:29 -0500 (Tue, 08 Jun 2010) | 1 line

    kill extra word
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diff --git a/Lib/test/test_unicode.py b/Lib/test/test_unicode.py
index 6e4f048..75637f8 100644
--- a/Lib/test/test_unicode.py
+++ b/Lib/test/test_unicode.py
@@ -687,6 +687,9 @@
         self.assertRaises(IndexError, "{:}".format)
         self.assertRaises(IndexError, "{:s}".format)
         self.assertRaises(IndexError, "{}".format)
+        big = "23098475029384702983476098230754973209482573"
+        self.assertRaises(ValueError, ("{" + big + "}").format)
+        self.assertRaises(ValueError, ("{[" + big + "]}").format, [0])
 
         # issue 6089
         self.assertRaises(ValueError, "{0[0]x}".format, [None])
diff --git a/Misc/NEWS b/Misc/NEWS
index 92a7c65..5fe35fc 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -12,6 +12,9 @@
 Core and Builtins
 -----------------
 
+- In the str.format(), raise a ValueError when indexes to arguments are too
+  large.
+
 - Issue #8766: Initialize _warnings module before importing the first module.
   Fix a crash if an empty directory called "encodings" exists in sys.path.
 
diff --git a/Objects/stringlib/string_format.h b/Objects/stringlib/string_format.h
index ecb00a9..bc70e97 100644
--- a/Objects/stringlib/string_format.h
+++ b/Objects/stringlib/string_format.h
@@ -373,6 +373,8 @@
         if (_FieldNameIterator_item(self, name) == 0)
             return 0;
         *name_idx = get_integer(name);
+        if (*name_idx == -1 && PyErr_Occurred())
+            return 0;
         break;
     default:
         /* Invalid character follows ']' */
@@ -429,6 +431,8 @@
 
     /* see if "first" is an integer, in which case it's used as an index */
     *first_idx = get_integer(first);
+    if (*first_idx == -1 && PyErr_Occurred())
+        return 0;
 
     field_name_is_empty = first->ptr >= first->end;