Make identifiers str (not str8) objects throughout. This affects the parser, various object implementations, and all places that put identifiers into C string literals. In testing, a number of crashes occurred as code would fail when the recursion limit was reached (such as the Unicode interning dictionary having key/value pairs where key is not value). To solve these, I added an overflowed flag, which allows for 50 more recursions after the limit was reached and the exception was raised, and a recursion_critical flag, which indicates that recursion absolutely must be allowed, i.e. that a certain call must not cause a stack overflow exception. There are still some places where both str and str8 are accepted as identifiers; these should eventually be removed.

--- a/Modules/gcmodule.c	Sat Jun 09 16:13:23 2007 +0000
+++ b/Modules/gcmodule.c	Sun Jun 10 09:51:05 2007 +0000
@@ -713,7 +713,7 @@
 	double t1 = 0.0;
 
 	if (delstr == NULL) {
-		delstr = PyString_InternFromString("__del__");
+		delstr = PyUnicode_InternFromString("__del__");
 		if (delstr == NULL)
 			Py_FatalError("gc couldn't allocate \"__del__\"");
 	}