bpo-39114: Fix tracing of except handlers with name binding (GH-17769)

When producing the bytecode of exception handlers with name binding (like `except Exception as e`) we need to produce a try-finally block to make sure that the name is deleted after the handler is executed to prevent cycles in the stack frame objects. The bytecode associated with this try-finally block does not have source lines associated and it was causing problems when the tracing functionality was running over it.

1 files changed, 45 insertions, 0 deletions

diff --git a/Lib/test/test_sys_settrace.py b/Lib/test/test_sys_settrace.py
index 0af015a..a0d1122 100644
--- a/Lib/test/test_sys_settrace.py
+++ b/Lib/test/test_sys_settrace.py
@@ -481,6 +481,51 @@ class TraceTestCase(unittest.TestCase):
             [(0, 'call'),
              (1, 'line')])
 
+    def test_18_except_with_name(self):
+        def func():
+            try:
+                try:
+                    raise Exception
+                except Exception as e:
+                    raise
+                    x = "Something"
+                    y = "Something"
+            except Exception:
+                pass
+
+        self.run_and_compare(func,
+            [(0, 'call'),
+             (1, 'line'),
+             (2, 'line'),
+             (3, 'line'),
+             (3, 'exception'),
+             (4, 'line'),
+             (5, 'line'),
+             (8, 'line'),
+             (9, 'line'),
+             (9, 'return')])
+
+    def test_19_except_with_finally(self):
+        def func():
+            try:
+                try:
+                    raise Exception
+                finally:
+                    y = "Something"
+            except Exception:
+                b = 23
+
+        self.run_and_compare(func,
+            [(0, 'call'),
+             (1, 'line'),
+             (2, 'line'),
+             (3, 'line'),
+             (3, 'exception'),
+             (5, 'line'),
+             (6, 'line'),
+             (7, 'line'),
+             (7, 'return')])
+
 
 class SkipLineEventsTraceTestCase(TraceTestCase):
     """Repeat the trace tests, but with per-line events skipped"""