https://github.com/python/cpython/commit/fab1405da8c93429ab1a1d3d3e1779d15b7223a2
commit: fab1405da8c93429ab1a1d3d3e1779d15b7223a2
branch: main
author: Jelle Zijlstra <[email protected]>
committer: JelleZijlstra <[email protected]>
date: 2026-10-20T21:34:23-07:00
summary:
gh-159739: Fix reference and error handling in warnings (#159758)
Do not release the borrowed skip_file_prefixes argument, and stop if
allocation of the fallback filename fails.
files:
A
Misc/NEWS.d/next/Core_and_Builtins/2026-10-19-19-33-35.gh-issue-159739.f81734.rst
M Lib/test/test_warnings/__init__.py
M Python/_warnings.c
diff --git a/Lib/test/test_warnings/__init__.py
b/Lib/test/test_warnings/__init__.py
index 7262fb0d38344c0..bfb43025de11405 100644
--- a/Lib/test/test_warnings/__init__.py
+++ b/Lib/test/test_warnings/__init__.py
@@ -698,6 +698,20 @@ def test_skip_file_prefixes_type_errors(self):
with self.assertRaises(TypeError):
warn("msg", skip_file_prefixes="a sequence of strs")
+ def test_skip_file_prefixes_empty_tuple_subclass(self):
+ with warnings_state(self.module):
+ self.module.simplefilter("always")
+ warn = warning_tests.warnings.warn
+ class EmptyTuple(tuple):
+ pass
+ # Passing an empty tuple subclass used to lead to a crash.
+ for _ in range(3):
+ with self.module.catch_warnings(record=True) as w:
+ warn("msg", skip_file_prefixes=EmptyTuple())
+ self.assertEqual(len(w), 1)
+ self.assertEqual(w[-1].filename, __file__)
+ self.assertEqual(w[-1].module, __name__)
+
def test_exec_filename_module(self):
filename = "<warnings-test>"
codeobj = compile(("import warnings\n"
diff --git
a/Misc/NEWS.d/next/Core_and_Builtins/2026-10-19-19-33-35.gh-issue-159739.f81734.rst
b/Misc/NEWS.d/next/Core_and_Builtins/2026-10-19-19-33-35.gh-issue-159739.f81734.rst
new file mode 100644
index 000000000000000..0342bdef3e86994
--- /dev/null
+++
b/Misc/NEWS.d/next/Core_and_Builtins/2026-10-19-19-33-35.gh-issue-159739.f81734.rst
@@ -0,0 +1,2 @@
+Fix a crash in :func:`warnings.warn` when ``skip_file_prefixes`` is an empty
tuple subclass.
+Propagate allocation errors when creating the fallback filename.
diff --git a/Python/_warnings.c b/Python/_warnings.c
index 8fecff060fdad93..86eae5deb859691 100644
--- a/Python/_warnings.c
+++ b/Python/_warnings.c
@@ -1053,6 +1053,9 @@ setup_context(Py_ssize_t stack_level,
if (f == NULL) {
globals = interp->sysdict;
*filename = PyUnicode_FromString("<sys>");
+ if (*filename == NULL) {
+ return 0;
+ }
*lineno = 0;
}
else {
@@ -1196,7 +1199,6 @@ warnings_warn_impl(PyObject *module, PyObject *message,
PyObject *category,
stacklevel = 2;
}
} else {
- Py_DECREF((PyObject *)skip_file_prefixes);
skip_file_prefixes = NULL;
}
}
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