From: Bartosz Sławecki <bartosz@ilikepython.com>
Date: Mon, 2 Mar 2026 11:01:32 +0000 (+0100)
Subject: gh-144851: Fix `__lazy_import__` crash with user-defined filters (#144852)
X-Git-Tag: v3.15.0a7~110
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=8bcb3eaa67959ec32bc4d683a79a0a67885925db;p=thirdparty%2FPython%2Fcpython.git

gh-144851: Fix `__lazy_import__` crash with user-defined filters (#144852)
---

diff --git a/Lib/test/test_lazy_import/__init__.py b/Lib/test/test_lazy_import/__init__.py
index df19af05246d..5d30ec229978 100644
--- a/Lib/test/test_lazy_import/__init__.py
+++ b/Lib/test/test_lazy_import/__init__.py
@@ -391,6 +391,11 @@ class DunderLazyImportTests(unittest.TestCase):
         import test.test_lazy_import.data.dunder_lazy_import
         self.assertNotIn("test.test_lazy_import.data.basic2", sys.modules)
 
+    def test_dunder_lazy_import_with_custom_filter(self):
+        sys.set_lazy_imports_filter(lambda importer, imported, fromlist: False)
+        import test.test_lazy_import.data.dunder_lazy_import
+        self.assertIn("test.test_lazy_import.data.basic2", sys.modules)
+
     def test_dunder_lazy_import_used(self):
         """Using __lazy_import__ result should trigger module load."""
         import test.test_lazy_import.data.dunder_lazy_import_used
diff --git a/Python/import.c b/Python/import.c
index 4c234a4a7043..dfc4d5707bfd 100644
--- a/Python/import.c
+++ b/Python/import.c
@@ -4512,6 +4512,10 @@ _PyImport_LazyImportModuleLevelObject(PyThreadState *tstate,
             assert(!PyErr_Occurred());
             modname = Py_NewRef(Py_None);
         }
+        if (fromlist == NULL) {
+            assert(!PyErr_Occurred());
+            fromlist = Py_NewRef(Py_None);
+        }
         PyObject *args[] = {modname, name, fromlist};
         PyObject *res = PyObject_Vectorcall(filter, args, 3, NULL);