bpo-34113: Fix a crash when using LLTRACE is on (GH-8517)

Fix a crash on negative STACKADJ() when Low-Level trace (LLTRACE) is enabled.

1 files changed, 31 insertions, 0 deletions

diff --git a/Lib/test/test_lltrace.py b/Lib/test/test_lltrace.py
new file mode 100644
index 0000000000..49fae81eef
--- /dev/null
+++ b/Lib/test/test_lltrace.py
@@ -0,0 +1,31 @@
+import os
+import textwrap
+import unittest
+
+from test import support
+from test.support.script_helper import assert_python_ok
+
+
+class TestLLTrace(unittest.TestCase):
+
+    def test_lltrace_does_not_crash_on_subscript_operator(self):
+        # If this test fails, it will reproduce a crash reported as
+        # bpo-34113. The crash happened at the command line console of
+        # debug Python builds with __ltrace__ enabled (only possible in console),
+        # when the interal Python stack was negatively adjusted
+        with open(support.TESTFN, 'w') as fd:
+            self.addCleanup(os.unlink, support.TESTFN)
+            fd.write(textwrap.dedent("""\
+            import code
+
+            console = code.InteractiveConsole()
+            console.push('__ltrace__ = 1')
+            console.push('a = [1, 2, 3]')
+            console.push('a[0] = 1')
+            print('unreachable if bug exists')
+            """))
+
+            assert_python_ok(support.TESTFN)
+
+if __name__ == "__main__":
+    unittest.main()