raise overflow error in Py3.3+ when non-BMP Unicode characters are coerced...

raise overflow error in Py3.3+ when non-BMP Unicode characters are coerced into a short Py_UNICODE value

CHANGES.rst

@@ -11,6 +11,10 @@ Features added
 Bugs fixed
 ----------
 
+* In CPython 3.3, converting a Unicode character to the Py_UNICODE type
+  could fail to raise an overflow for non-BMP characters that do not fit
+  into a wchar_t on the current platform.
+
 Other changes
 -------------
 

Cython/Utility/TypeConversion.c

@@ -209,8 +209,12 @@ static CYTHON_INLINE Py_UNICODE __Pyx_PyObject_AsPy_UNICODE(PyObject*);
 static CYTHON_INLINE Py_UNICODE __Pyx_PyObject_AsPy_UNICODE(PyObject* x) {
     long ival;
     #if CYTHON_PEP393_ENABLED
+    #if Py_UNICODE_SIZE > 2
     const long maxval = 1114111;
     #else
+    const long maxval = 65535;
+    #endif
+    #else
     static long maxval = 0;
     #endif
     if (PyUnicode_Check(x)) {