Better behavior when stepping over yield[from]. Fixes issue 16596. By Xavier de Gaye.

1 files changed, 10 insertions, 2 deletions

diff --git a/Lib/pdb.py b/Lib/pdb.py
index 2268d303906..dd7ceb8927d 100755
--- a/Lib/pdb.py
+++ b/Lib/pdb.py
@@ -297,8 +297,16 @@ class Pdb(bdb.Bdb, cmd.Cmd):
             return
         exc_type, exc_value, exc_traceback = exc_info
         frame.f_locals['__exception__'] = exc_type, exc_value
-        self.message(traceback.format_exception_only(exc_type,
-                                                     exc_value)[-1].strip())
+
+        # An 'Internal StopIteration' exception is an exception debug event
+        # issued by the interpreter when handling a subgenerator run with
+        # 'yield from' or a generator controled by a for loop. No exception has
+        # actually occured in this case. The debugger uses this debug event to
+        # stop when the debuggee is returning from such generators.
+        prefix = 'Internal ' if (not exc_traceback
+                                    and exc_type is StopIteration) else ''
+        self.message('%s%s' % (prefix,
+            traceback.format_exception_only(exc_type, exc_value)[-1].strip()))
         self.interaction(frame, exc_traceback)
 
     # General interaction function