From: Shantanu <12621235+hauntsaninja@users.noreply.github.com>
Date: Thu, 21 Dec 2023 21:24:10 +0000 (-0800)
Subject: gh-95754: Better AttributeError on partially initialised module (#112577)
X-Git-Tag: v3.13.0a3~298
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=61e818409567ce452af60605937cdedf582f6293;p=thirdparty%2FPython%2Fcpython.git

gh-95754: Better AttributeError on partially initialised module (#112577)

Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>
---

diff --git a/Lib/test/test_import/__init__.py b/Lib/test/test_import/__init__.py
index 48c0a43f29e2..7b0126226c4a 100644
--- a/Lib/test/test_import/__init__.py
+++ b/Lib/test/test_import/__init__.py
@@ -1632,6 +1632,14 @@ class CircularImportTests(unittest.TestCase):
             str(cm.exception),
         )
 
+    def test_circular_import(self):
+        with self.assertRaisesRegex(
+            AttributeError,
+            r"partially initialized module 'test.test_import.data.circular_imports.import_cycle' "
+            r"from '.*' has no attribute 'some_attribute' \(most likely due to a circular import\)"
+        ):
+            import test.test_import.data.circular_imports.import_cycle
+
     def test_absolute_circular_submodule(self):
         with self.assertRaises(AttributeError) as cm:
             import test.test_import.data.circular_imports.subpkg2.parent
diff --git a/Lib/test/test_import/data/circular_imports/import_cycle.py b/Lib/test/test_import/data/circular_imports/import_cycle.py
new file mode 100644
index 000000000000..cd9507b5f69e
--- /dev/null
+++ b/Lib/test/test_import/data/circular_imports/import_cycle.py
@@ -0,0 +1,3 @@
+import test.test_import.data.circular_imports.import_cycle as m
+
+m.some_attribute
diff --git a/Misc/NEWS.d/next/Core and Builtins/2023-12-01-08-16-10.gh-issue-95754.ae4gwy.rst b/Misc/NEWS.d/next/Core and Builtins/2023-12-01-08-16-10.gh-issue-95754.ae4gwy.rst
new file mode 100644
index 000000000000..0884bc4a4be7
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2023-12-01-08-16-10.gh-issue-95754.ae4gwy.rst	
@@ -0,0 +1 @@
+Provide a better error message when accessing invalid attributes on partially initialized modules. The origin of the module being accessed is now included in the message to help with the common issue of shadowing other modules.
diff --git a/Objects/moduleobject.c b/Objects/moduleobject.c
index e2741fef6deb..3a1c516658dc 100644
--- a/Objects/moduleobject.c
+++ b/Objects/moduleobject.c
@@ -788,7 +788,7 @@ PyObject*
 _Py_module_getattro_impl(PyModuleObject *m, PyObject *name, int suppress)
 {
     // When suppress=1, this function suppresses AttributeError.
-    PyObject *attr, *mod_name, *getattr;
+    PyObject *attr, *mod_name, *getattr, *origin;
     attr = _PyObject_GenericGetAttrWithDict((PyObject *)m, name, NULL, suppress);
     if (attr) {
         return attr;
@@ -831,11 +831,31 @@ _Py_module_getattro_impl(PyModuleObject *m, PyObject *name, int suppress)
         if (suppress != 1) {
             int rc = _PyModuleSpec_IsInitializing(spec);
             if (rc > 0) {
-                PyErr_Format(PyExc_AttributeError,
+                int valid_spec = PyObject_GetOptionalAttr(spec, &_Py_ID(origin), &origin);
+                if (valid_spec == -1) {
+                    Py_XDECREF(spec);
+                    Py_DECREF(mod_name);
+                    return NULL;
+                }
+                if (valid_spec == 1 && !PyUnicode_Check(origin)) {
+                    valid_spec = 0;
+                    Py_DECREF(origin);
+                }
+                if (valid_spec == 1) {
+                    PyErr_Format(PyExc_AttributeError,
+                                "partially initialized "
+                                "module '%U' from '%U' has no attribute '%U' "
+                                "(most likely due to a circular import)",
+                                mod_name, origin, name);
+                    Py_DECREF(origin);
+                }
+                else {
+                    PyErr_Format(PyExc_AttributeError,
                                 "partially initialized "
                                 "module '%U' has no attribute '%U' "
                                 "(most likely due to a circular import)",
                                 mod_name, name);
+                }
             }
             else if (rc == 0) {
                 rc = _PyModuleSpec_IsUninitializedSubmodule(spec, name);