From 474220e3a58d739acc5154eb3e000461d2222d62 Mon Sep 17 00:00:00 2001
From: Sebastian Berg <sebastianb@nvidia.com>
Date: Sat, 24 Dec 2022 00:43:19 +0100
Subject: [PATCH] gh-99947: Ensure unreported errors are chained for
 SystemError during import (GH-99946)

---
 Lib/test/test_importlib/extension/test_loader.py         | 7 ++++++-
 .../C API/2022-12-02-09-31-19.gh-issue-99947.Ski7OC.rst  | 1 +
 Objects/moduleobject.c                                   | 9 +++++----
 Python/importdl.c                                        | 3 +--
 4 files changed, 13 insertions(+), 7 deletions(-)
 create mode 100644 Misc/NEWS.d/next/C API/2022-12-02-09-31-19.gh-issue-99947.Ski7OC.rst

diff --git a/Lib/test/test_importlib/extension/test_loader.py b/Lib/test/test_importlib/extension/test_loader.py
index d69192b56bacb6..3bf2bbdcdcc4e6 100644
--- a/Lib/test/test_importlib/extension/test_loader.py
+++ b/Lib/test/test_importlib/extension/test_loader.py
@@ -351,9 +351,14 @@ def test_bad_modules(self):
                 ]:
             with self.subTest(name_base):
                 name = self.name + '_' + name_base
-                with self.assertRaises(SystemError):
+                with self.assertRaises(SystemError) as cm:
                     self.load_module_by_name(name)
 
+                # If there is an unreported exception, it should be chained
+                # with the `SystemError`.
+                if "unreported_exception" in name_base:
+                    self.assertIsNotNone(cm.exception.__cause__)
+
     def test_nonascii(self):
         # Test that modules with non-ASCII names can be loaded.
         # punycode behaves slightly differently in some-ASCII and no-ASCII
diff --git a/Misc/NEWS.d/next/C API/2022-12-02-09-31-19.gh-issue-99947.Ski7OC.rst b/Misc/NEWS.d/next/C API/2022-12-02-09-31-19.gh-issue-99947.Ski7OC.rst
new file mode 100644
index 00000000000000..fbed192d317b34
--- /dev/null
+++ b/Misc/NEWS.d/next/C API/2022-12-02-09-31-19.gh-issue-99947.Ski7OC.rst	
@@ -0,0 +1 @@
+Raising SystemError on import will now have its cause be set to the original unexpected exception.
diff --git a/Objects/moduleobject.c b/Objects/moduleobject.c
index 8e03f2446f6fcd..24190e320ee6d6 100644
--- a/Objects/moduleobject.c
+++ b/Objects/moduleobject.c
@@ -327,9 +327,10 @@ PyModule_FromDefAndSpec2(PyModuleDef* def, PyObject *spec, int module_api_versio
             goto error;
         } else {
             if (PyErr_Occurred()) {
-                PyErr_Format(PyExc_SystemError,
-                            "creation of module %s raised unreported exception",
-                            name);
+                _PyErr_FormatFromCause(
+                    PyExc_SystemError,
+                    "creation of module %s raised unreported exception",
+                    name);
                 goto error;
             }
         }
@@ -431,7 +432,7 @@ PyModule_ExecDef(PyObject *module, PyModuleDef *def)
                     return -1;
                 }
                 if (PyErr_Occurred()) {
-                    PyErr_Format(
+                    _PyErr_FormatFromCause(
                         PyExc_SystemError,
                         "execution of module %s raised unreported exception",
                         name);
diff --git a/Python/importdl.c b/Python/importdl.c
index 40227674ca47ee..91fa06f49c2897 100644
--- a/Python/importdl.c
+++ b/Python/importdl.c
@@ -180,8 +180,7 @@ _PyImport_LoadDynamicModuleWithSpec(PyObject *spec, FILE *fp)
         }
         goto error;
     } else if (PyErr_Occurred()) {
-        PyErr_Clear();
-        PyErr_Format(
+        _PyErr_FormatFromCause(
             PyExc_SystemError,
             "initialization of %s raised unreported exception",
             name_buf);