This patch adds a new Python C API called PyString_AsStringAndSize()

which implements the automatic conversion from Unicode to a string
object using the default encoding.

The new API is then put to use to have eval() and exec accept
Unicode objects as code parameter. This closes bugs #110924
and #113890.

As side-effect, the traditional C APIs PyString_Size() and
PyString_AsString() will also accept Unicode objects as
parameters.

Include/stringobject.h

@@ -103,6 +103,21 @@ extern DL_IMPORT(PyObject*) PyString_AsEncodedString(
     const char *errors		/* error handling */
     );
 
+/* Provides access to the internal data buffer and size of a string
+   object or the default encoded version of an Unicode object. Passing
+   NULL as *len parameter will force the string buffer to be
+   0-terminated (passing a string with embedded NULL characters will
+   cause an exception).  */
+
+extern DL_IMPORT(int) PyString_AsStringAndSize(
+    register PyObject *obj,	/* string or Unicode object */
+    register char **s,		/* pointer to buffer variable */
+    register int *len		/* pointer to length variable or NULL
+				   (only possible for 0-terminated
+				   strings) */
+    );
+    
+
 #ifdef __cplusplus
 }
 #endif