Bug #1704793: Raise KeyError if unicodedata.lookup cannot

represent the result in a single character.

Lib/test/test_unicodedata.py

@@ -6,7 +6,7 @@
 
 """#"
 import unittest, test.test_support
-import hashlib
+import hashlib, sys
 
 encoding = 'utf-8'
 
@@ -214,6 +214,10 @@ class UnicodeMiscTest(UnicodeDatabaseTest):
                 count += 1
         self.assert_(count >= 10) # should have tested at least the ASCII digits
 
+    def test_bug_1704793(self):
+        if sys.maxunicode == 65535:
+            self.assertRaises(KeyError, self.db.lookup, "GOTHIC LETTER FAIHU")
+
 def test_main():
     test.test_support.run_unittest(
         UnicodeMiscTest,

Misc/NEWS

@@ -26,6 +26,9 @@ Core and builtins
 Library
 -------
 
+- Bug #1704793: Raise KeyError if unicodedata.lookup cannot
+  represent the result in a single character.
+
 - Change location of the package index to pypi.python.org/pypi
 
 - Bug #1701409: Fix a segfault in printing ctypes.c_char_p and

Modules/unicodedata.c

@@ -1102,6 +1102,16 @@ unicodedata_lookup(PyObject* self, PyObject* args)
         return NULL;
     }
 
+#ifndef Py_UNICODE_WIDE
+    if (code >= 0x10000) {
+        /* Raise KeyError for compatibility; the possibly more
+           correct ValueError was not documented as a possible
+           exception for 2.5.x and earlier. */
+        PyErr_Format(PyExc_KeyError, "result %d larger than sys.maxunicode",
+                     code);
+        return NULL;
+    }
+#endif
     str[0] = (Py_UNICODE) code;
     return PyUnicode_FromUnicode(str, 1);    
 }