SF patch 419176 from MvL; fixed bug 418977

Two errors in dict_to_map() helper used by PyFrame_LocalsToFast().

Lib/test/output/test_scope

@@ -18,3 +18,4 @@ test_scope
 17. class and global
 18. verify that locals() works
 19. var is bound and free in class
+20. interaction with trace function

Lib/test/test_scope.py

@@ -447,3 +447,23 @@ def f(x):
 
 inst = f(3)()
 verify(inst.a == inst.m())
+
+print "20. interaction with trace function"
+
+import sys
+def tracer(a,b,c):
+    return tracer
+
+def adaptgetter(name, klass, getter):
+    kind, des = getter
+    if kind == 1:       # AV happens when stepping from this line to next
+        if des == "":
+            des = "_%s__%s" % (klass.__name__, name)
+        return lambda obj: getattr(obj, des)
+
+class TestClass:
+    pass
+
+sys.settrace(tracer)
+adaptgetter("foo", TestClass, (1, ""))
+sys.settrace(None)

Objects/frameobject.c

@@ -283,12 +283,9 @@ dict_to_map(PyObject *map, int nmap, PyObject *dict, PyObject **values,
 		PyObject *value = PyDict_GetItem(dict, key);
 		Py_XINCREF(value);
 		if (deref) {
-			if (value) {
+			if (value || clear) {
 				if (PyCell_Set(values[j], value) < 0)
 					PyErr_Clear();
-			} else if (clear) {
-				Py_XDECREF(values[j]);
-				values[j] = value;
 			}
 		} else if (value != NULL || clear) {
 			Py_XDECREF(values[j]);
@@ -370,10 +367,10 @@ PyFrame_LocalsToFast(PyFrameObject *f, int clear)
 			return;
 		dict_to_map(f->f_code->co_cellvars, 
 			    PyTuple_GET_SIZE(f->f_code->co_cellvars),
-			    locals, fast, 1, clear);
+			    locals, fast + f->f_nlocals, 1, clear);
 		dict_to_map(f->f_code->co_freevars, 
 			    PyTuple_GET_SIZE(f->f_code->co_freevars),
-			    locals, fast, 1, clear);
+			    locals, fast + f->f_nlocals + f->f_ncells, 1, clear);
 	}
 	PyErr_Restore(error_type, error_value, error_traceback);
 }