[3.13] gh-127651: Use __file__ in diagnostics if origin is missing (#127660) (#127775)

gh-127651: Use __file__ in diagnostics if origin is missing (#127660)

See the left hand side in https://github.com/python/cpython/pull/123929/files#diff-c22186367cbe20233e843261998dc027ae5f1f8c0d2e778abfa454ae74cc59deL2840-L2849

---------

Co-authored-by: Serhiy Storchaka <[email protected]>
(cherry picked from commit 3983527)

Author: hauntsaninja

Lib/test/test_import/__init__.py

@@ -826,6 +826,50 @@ def test_issue105979(self):
         self.assertIn("Frozen object named 'x' is invalid",
                       str(cm.exception))
 
+    def test_frozen_module_from_import_error(self):
+        with self.assertRaises(ImportError) as cm:
+            from os import this_will_never_exist
+        self.assertIn(
+            f"cannot import name 'this_will_never_exist' from 'os' ({os.__file__})",
+            str(cm.exception),
+        )
+        with self.assertRaises(ImportError) as cm:
+            from sys import this_will_never_exist
+        self.assertIn(
+            "cannot import name 'this_will_never_exist' from 'sys' (unknown location)",
+            str(cm.exception),
+        )
+
+        scripts = [
+            """
+import os
+os.__spec__.has_location = False
+os.__file__ = []
+from os import this_will_never_exist
+""",
+            """
+import os
+os.__spec__.has_location = False
+del os.__file__
+from os import this_will_never_exist
+""",
+              """
+import os
+os.__spec__.origin = []
+os.__file__ = []
+from os import this_will_never_exist
+"""
+        ]
+        for script in scripts:
+            with self.subTest(script=script):
+                expected_error = (
+                    b"cannot import name 'this_will_never_exist' "
+                    b"from 'os' (unknown location)"
+                )
+                popen = script_helper.spawn_python("-c", script)
+                stdout, stderr = popen.communicate()
+                self.assertIn(expected_error, stdout)
+
     def test_script_shadowing_stdlib(self):
         script_errors = [
             (
@@ -1087,7 +1131,7 @@ class substr(str):
 except AttributeError as e:
     print(str(e))
 
-fractions.__spec__.origin = 0
+fractions.__spec__.origin = []
 try:
     fractions.Fraction
 except AttributeError as e:
@@ -1111,7 +1155,7 @@ class substr(str):
 except ImportError as e:
     print(str(e))
 
-fractions.__spec__.origin = 0
+fractions.__spec__.origin = []
 try:
     from fractions import Fraction
 except ImportError as e:

Misc/NEWS.d/next/Core and Builtins/2024-12-06-01-09-40.gh-issue-127651.80cm6j.rst

@@ -0,0 +1 @@
+When raising :exc:`ImportError` for missing symbols in ``from`` imports, use ``__file__`` in the error message if ``__spec__.origin`` is not a location

Python/ceval.c

@@ -2785,6 +2785,20 @@ import_from(PyThreadState *tstate, PyObject *v, PyObject *name)
         }
     }
 
+    if (origin == NULL) {
+        // Fall back to __file__ for diagnostics if we don't have
+        // an origin that is a location
+        origin = PyModule_GetFilenameObject(v);
+        if (origin == NULL) {
+            if (!PyErr_ExceptionMatches(PyExc_SystemError)) {
+                goto done;
+            }
+            // PyModule_GetFilenameObject raised "module filename missing"
+            _PyErr_Clear(tstate);
+        }
+        assert(origin == NULL || PyUnicode_Check(origin));
+    }
+
     if (is_possibly_shadowing_stdlib) {
         assert(origin);
         errmsg = PyUnicode_FromFormat(
@@ -2845,9 +2859,11 @@ import_from(PyThreadState *tstate, PyObject *v, PyObject *name)
     }
 
 done_with_errmsg:
-    /* NULL checks for errmsg, mod_name, origin done by PyErr_SetImportError. */
-    _PyErr_SetImportErrorWithNameFrom(errmsg, mod_name, origin, name);
-    Py_DECREF(errmsg);
+    if (errmsg != NULL) {
+        /* NULL checks for mod_name and origin done by _PyErr_SetImportErrorWithNameFrom */
+        _PyErr_SetImportErrorWithNameFrom(errmsg, mod_name, origin, name);
+        Py_DECREF(errmsg);
+    }
 
 done:
     Py_XDECREF(origin);