bpo-42908: Mark cleanup code at end of try-except and with artificial (#24202)

* Mark bytecodes at end of try-except as artificial.

* Make sure that the CFG is consistent throughout optimiization. 

* Extend line-number propagation logic so that implicit returns after 'try-except' or 'with' have the correct line numbers.

* Update importlib

1 files changed, 40 insertions, 0 deletions

diff --git a/Lib/test/test_sys_settrace.py b/Lib/test/test_sys_settrace.py
index 83b03925c3..4298986250 100644
--- a/Lib/test/test_sys_settrace.py
+++ b/Lib/test/test_sys_settrace.py
@@ -916,6 +916,46 @@ class TraceTestCase(unittest.TestCase):
              (7, 'line'),
              (7, 'return')])
 
+    def test_if_false_in_with(self):
+
+        class C:
+            def __enter__(self):
+                return self
+            def __exit__(*args):
+                pass
+
+        def func():
+            with C():
+                if False:
+                    pass
+
+        self.run_and_compare(func,
+            [(0, 'call'),
+             (1, 'line'),
+             (-5, 'call'),
+             (-4, 'line'),
+             (-4, 'return'),
+             (2, 'line'),
+             (-3, 'call'),
+             (-2, 'line'),
+             (-2, 'return'),
+             (2, 'return')])
+
+    def test_if_false_in_try_except(self):
+
+        def func():
+            try:
+                if False:
+                    pass
+            except Exception:
+                X
+
+        self.run_and_compare(func,
+            [(0, 'call'),
+             (1, 'line'),
+             (2, 'line'),
+             (2, 'return')])
+
 
 class SkipLineEventsTraceTestCase(TraceTestCase):
     """Repeat the trace tests, but with per-line events skipped"""