bdb: Re-enable usage of frame.f_trace.

Requires micropython/micropython#8767

python-stdlib/bdb/bdb.py

@@ -126,11 +126,11 @@ def dispatch_line(self, frame):
         return self.trace_dispatch
 
     def is_coroutine(self, frame):
-        ## MPY: co_flags attrib not available, compatible method of detecting coroutine TBD 
+        ## MPY: co_flags attrib not available, compatible method of detecting coroutine TBD
         # return frame.f_code.co_flags & GENERATOR_AND_COROUTINE_FLAGS
         return False
 
-    
+
     def dispatch_call(self, frame, arg):
         """Invoke user function and return trace function for call event.
 
@@ -321,9 +321,8 @@ def set_step(self):
         # for performance reasons) when returning from the current frame.
         if self.frame_returning:
             caller_frame = self.frame_returning.f_back
-            ## MPY: f_trace attrib not yet available
-            # if caller_frame and not caller_frame.f_trace:
-            #     caller_frame.f_trace = self.trace_dispatch
+            if caller_frame and not caller_frame.f_trace:
+                caller_frame.f_trace = self.trace_dispatch
         self._set_stopinfo(None, None)
 
     def set_next(self, frame):
@@ -345,11 +344,10 @@ def set_trace(self, frame=None):
         if frame is None:
             frame = sys._getframe(1)
         self.reset()
-        ## MPY: f_trace attrib not yet available
-        # while frame:
-            # frame.f_trace = self.trace_dispatch
-            # self.botframe = frame
-            # frame = frame.f_back
+        while frame:
+            frame.f_trace = self.trace_dispatch
+            self.botframe = frame
+            frame = frame.f_back
         self.set_step()
         sys.settrace(self.trace_dispatch)
 
@@ -365,10 +363,9 @@ def set_continue(self):
             sys.settrace(None)
             ## MPY: was sys._getframe().f_back but f_back missing when inside trace dispatch functions
             frame = sys._getframe(1)
-            ## MPY: f_trace attrib not yet available
-            # while frame and frame is not self.botframe:
-            #     del frame.f_trace
-            #     frame = frame.f_back
+            while frame and frame is not self.botframe:
+                del frame.f_trace
+                frame = frame.f_back
 
     def set_quit(self):
         """Set quitting attribute to True.