From a458be3263b4cb92f3fde726461e8ef44b2a4a9d Mon Sep 17 00:00:00 2001
From: Dennis Sweeney <36520290+sweeneyde@users.noreply.github.com>
Date: Mon, 23 May 2022 08:58:41 -0400
Subject: [PATCH] gh-93061: Mark as artificial: backwards jump after async for
 (GH-93062)

---
 Lib/test/test_sys_settrace.py                 | 52 +++++++++++++++++++
 ...2-05-22-02-37-50.gh-issue-93061.r70Imp.rst |  1 +
 Python/compile.c                              |  2 +
 3 files changed, 55 insertions(+)
 create mode 100644 Misc/NEWS.d/next/Core and Builtins/2022-05-22-02-37-50.gh-issue-93061.r70Imp.rst

diff --git a/Lib/test/test_sys_settrace.py b/Lib/test/test_sys_settrace.py
index 9cc6bcfcab5..162fd832858 100644
--- a/Lib/test/test_sys_settrace.py
+++ b/Lib/test/test_sys_settrace.py
@@ -609,6 +609,58 @@ class TraceTestCase(unittest.TestCase):
         self.compare_events(doit_async.__code__.co_firstlineno,
                             tracer.events, events)
 
+    def test_async_for_backwards_jump_has_no_line(self):
+        async def arange(n):
+            for i in range(n):
+                yield i
+        async def f():
+            async for i in arange(3):
+                if i > 100:
+                    break # should never be traced
+
+        tracer = self.make_tracer()
+        coro = f()
+        try:
+            sys.settrace(tracer.trace)
+            coro.send(None)
+        except Exception:
+            pass
+        finally:
+            sys.settrace(None)
+
+        events = [
+            (0, 'call'),
+            (1, 'line'),
+            (-3, 'call'),
+            (-2, 'line'),
+            (-1, 'line'),
+            (-1, 'return'),
+            (1, 'exception'),
+            (2, 'line'),
+            (1, 'line'),
+            (-1, 'call'),
+            (-2, 'line'),
+            (-1, 'line'),
+            (-1, 'return'),
+            (1, 'exception'),
+            (2, 'line'),
+            (1, 'line'),
+            (-1, 'call'),
+            (-2, 'line'),
+            (-1, 'line'),
+            (-1, 'return'),
+            (1, 'exception'),
+            (2, 'line'),
+            (1, 'line'),
+            (-1, 'call'),
+            (-2, 'line'),
+            (-2, 'return'),
+            (1, 'exception'),
+            (1, 'return'),
+        ]
+        self.compare_events(f.__code__.co_firstlineno,
+                            tracer.events, events)
+
     def test_21_repeated_pass(self):
         def func():
             pass
diff --git a/Misc/NEWS.d/next/Core and Builtins/2022-05-22-02-37-50.gh-issue-93061.r70Imp.rst b/Misc/NEWS.d/next/Core and Builtins/2022-05-22-02-37-50.gh-issue-93061.r70Imp.rst
new file mode 100644
index 00000000000..d41e59028ad
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2022-05-22-02-37-50.gh-issue-93061.r70Imp.rst	
@@ -0,0 +1 @@
+Backward jumps after ``async for`` loops are no longer given dubious line numbers.
diff --git a/Python/compile.c b/Python/compile.c
index c862c10a83e..a4738c1f48f 100644
--- a/Python/compile.c
+++ b/Python/compile.c
@@ -3148,6 +3148,8 @@ compiler_async_for(struct compiler *c, stmt_ty s)
     /* Success block for __anext__ */
     VISIT(c, expr, s->v.AsyncFor.target);
     VISIT_SEQ(c, stmt, s->v.AsyncFor.body);
+    /* Mark jump as artificial */
+    UNSET_LOC(c);
     ADDOP_JUMP(c, JUMP, start);
 
     compiler_pop_fblock(c, FOR_LOOP, start);