gh-123930: Better error for "from imports" when script shadows module (#123929)

diff --git a/Doc/whatsnew/3.13.rst b/Doc/whatsnew/3.13.rst
index f9e74a9b8ff9c666e76d6108931e34e579070cf1..de4c7fd4c0486ba91a32508419f1a3d032fad2d4 100644 (file)
--- a/Doc/whatsnew/3.13.rst
+++ b/Doc/whatsnew/3.13.rst
@@ -274,7 +274,7 @@ Improved error messages
        File "/home/me/random.py", line 3, in <module>
          print(random.randint(5))
                ^^^^^^^^^^^^^^
-     AttributeError: module 'random' has no attribute 'randint' (consider renaming '/home/me/random.py' since it has the same name as the standard library module named 'random' and the import system gives it precedence)
+     AttributeError: module 'random' has no attribute 'randint' (consider renaming '/home/me/random.py' since it has the same name as the standard library module named 'random' and prevents importing that standard library module)
 
   Similarly, if a script has the same name as a third-party
   module that it attempts to import and this results in errors,
@@ -289,7 +289,7 @@ Improved error messages
        File "/home/me/numpy.py", line 3, in <module>
          np.array([1, 2, 3])
          ^^^^^^^^
-     AttributeError: module 'numpy' has no attribute 'array' (consider renaming '/home/me/numpy.py' if it has the same name as a third-party module you intended to import)
+     AttributeError: module 'numpy' has no attribute 'array' (consider renaming '/home/me/numpy.py' if it has the same name as a library you intended to import)
 
   (Contributed by Shantanu Jain in :gh:`95754`.)
 

diff --git a/Include/internal/pycore_moduleobject.h b/Include/internal/pycore_moduleobject.h
index cc2dda48ed9f2820937eabceb9efed01cb0fffb5..9bb282a13a9659c1991319496cf4920b2780bbc4 100644 (file)
--- a/Include/internal/pycore_moduleobject.h
+++ b/Include/internal/pycore_moduleobject.h
@@ -11,6 +11,8 @@ extern "C" {
 extern void _PyModule_Clear(PyObject *);
 extern void _PyModule_ClearDict(PyObject *);
 extern int _PyModuleSpec_IsInitializing(PyObject *);
+extern int _PyModuleSpec_GetFileOrigin(PyObject *, PyObject **);
+extern int _PyModule_IsPossiblyShadowing(PyObject *);
 
 extern int _PyModule_IsExtension(PyObject *obj);
 

diff --git a/Lib/test/test_import/__init__.py b/Lib/test/test_import/__init__.py
index 5d0d02480b3929e9bd63e677a43739924bdd4f00..5b7ba90b2cc7c60e7878bd891ce4b510451287cd 100644 (file)
--- a/Lib/test/test_import/__init__.py
+++ b/Lib/test/test_import/__init__.py
@@ -804,104 +804,133 @@ class ImportTests(unittest.TestCase):
                       str(cm.exception))
 
     def test_script_shadowing_stdlib(self):
-        with os_helper.temp_dir() as tmp:
-            with open(os.path.join(tmp, "fractions.py"), "w", encoding='utf-8') as f:
-                f.write("import fractions\nfractions.Fraction")
-
-            expected_error = (
-                rb"AttributeError: module 'fractions' has no attribute 'Fraction' "
-                rb"\(consider renaming '.*fractions.py' since it has the "
-                rb"same name as the standard library module named 'fractions' "
-                rb"and the import system gives it precedence\)"
+        script_errors = [
+            (
+                "import fractions\nfractions.Fraction",
+                rb"AttributeError: module 'fractions' has no attribute 'Fraction'"
+            ),
+            (
+                "from fractions import Fraction",
+                rb"ImportError: cannot import name 'Fraction' from 'fractions'"
             )
+        ]
+        for script, error in script_errors:
+            with self.subTest(script=script), os_helper.temp_dir() as tmp:
+                with open(os.path.join(tmp, "fractions.py"), "w", encoding='utf-8') as f:
+                    f.write(script)
+
+                expected_error = error + (
+                    rb" \(consider renaming '.*fractions.py' since it has the "
+                    rb"same name as the standard library module named 'fractions' "
+                    rb"and prevents importing that standard library module\)"
+                )
 
-            popen = script_helper.spawn_python(os.path.join(tmp, "fractions.py"), cwd=tmp)
-            stdout, stderr = popen.communicate()
-            self.assertRegex(stdout, expected_error)
+                popen = script_helper.spawn_python(os.path.join(tmp, "fractions.py"), cwd=tmp)
+                stdout, stderr = popen.communicate()
+                self.assertRegex(stdout, expected_error)
 
-            popen = script_helper.spawn_python('-m', 'fractions', cwd=tmp)
-            stdout, stderr = popen.communicate()
-            self.assertRegex(stdout, expected_error)
+                popen = script_helper.spawn_python('-m', 'fractions', cwd=tmp)
+                stdout, stderr = popen.communicate()
+                self.assertRegex(stdout, expected_error)
 
-            popen = script_helper.spawn_python('-c', 'import fractions', cwd=tmp)
-            stdout, stderr = popen.communicate()
-            self.assertRegex(stdout, expected_error)
+                popen = script_helper.spawn_python('-c', 'import fractions', cwd=tmp)
+                stdout, stderr = popen.communicate()
+                self.assertRegex(stdout, expected_error)
 
-            # and there's no error at all when using -P
-            popen = script_helper.spawn_python('-P', 'fractions.py', cwd=tmp)
-            stdout, stderr = popen.communicate()
-            self.assertEqual(stdout, b'')
+                # and there's no error at all when using -P
+                popen = script_helper.spawn_python('-P', 'fractions.py', cwd=tmp)
+                stdout, stderr = popen.communicate()
+                self.assertEqual(stdout, b'')
 
-            tmp_child = os.path.join(tmp, "child")
-            os.mkdir(tmp_child)
+                tmp_child = os.path.join(tmp, "child")
+                os.mkdir(tmp_child)
 
-            # test the logic with different cwd
-            popen = script_helper.spawn_python(os.path.join(tmp, "fractions.py"), cwd=tmp_child)
-            stdout, stderr = popen.communicate()
-            self.assertRegex(stdout, expected_error)
+                # test the logic with different cwd
+                popen = script_helper.spawn_python(os.path.join(tmp, "fractions.py"), cwd=tmp_child)
+                stdout, stderr = popen.communicate()
+                self.assertRegex(stdout, expected_error)
 
-            popen = script_helper.spawn_python('-m', 'fractions', cwd=tmp_child)
-            stdout, stderr = popen.communicate()
-            self.assertEqual(stdout, b'')  # no error
+                popen = script_helper.spawn_python('-m', 'fractions', cwd=tmp_child)
+                stdout, stderr = popen.communicate()
+                self.assertEqual(stdout, b'')  # no error
 
-            popen = script_helper.spawn_python('-c', 'import fractions', cwd=tmp_child)
-            stdout, stderr = popen.communicate()
-            self.assertEqual(stdout, b'')  # no error
+                popen = script_helper.spawn_python('-c', 'import fractions', cwd=tmp_child)
+                stdout, stderr = popen.communicate()
+                self.assertEqual(stdout, b'')  # no error
 
     def test_package_shadowing_stdlib_module(self):
-        with os_helper.temp_dir() as tmp:
-            os.mkdir(os.path.join(tmp, "fractions"))
-            with open(os.path.join(tmp, "fractions", "__init__.py"), "w", encoding='utf-8') as f:
-                f.write("shadowing_module = True")
-            with open(os.path.join(tmp, "main.py"), "w", encoding='utf-8') as f:
-                f.write("""
-import fractions
-fractions.shadowing_module
-fractions.Fraction
-""")
-
-            expected_error = (
-                rb"AttributeError: module 'fractions' has no attribute 'Fraction' "
-                rb"\(consider renaming '.*fractions.__init__.py' since it has the "
-                rb"same name as the standard library module named 'fractions' "
-                rb"and the import system gives it precedence\)"
+        script_errors = [
+            (
+                "fractions.Fraction",
+                rb"AttributeError: module 'fractions' has no attribute 'Fraction'"
+            ),
+            (
+                "from fractions import Fraction",
+                rb"ImportError: cannot import name 'Fraction' from 'fractions'"
             )
+        ]
+        for script, error in script_errors:
+            with self.subTest(script=script), os_helper.temp_dir() as tmp:
+                os.mkdir(os.path.join(tmp, "fractions"))
+                with open(
+                    os.path.join(tmp, "fractions", "__init__.py"), "w", encoding='utf-8'
+                ) as f:
+                    f.write("shadowing_module = True")
+                with open(os.path.join(tmp, "main.py"), "w", encoding='utf-8') as f:
+                    f.write("import fractions; fractions.shadowing_module\n")
+                    f.write(script)
+
+                expected_error = error + (
+                    rb" \(consider renaming '.*[\\/]fractions[\\/]+__init__.py' since it has the "
+                    rb"same name as the standard library module named 'fractions' "
+                    rb"and prevents importing that standard library module\)"
+                )
 
-            popen = script_helper.spawn_python(os.path.join(tmp, "main.py"), cwd=tmp)
-            stdout, stderr = popen.communicate()
-            self.assertRegex(stdout, expected_error)
+                popen = script_helper.spawn_python(os.path.join(tmp, "main.py"), cwd=tmp)
+                stdout, stderr = popen.communicate()
+                self.assertRegex(stdout, expected_error)
 
-            popen = script_helper.spawn_python('-m', 'main', cwd=tmp)
-            stdout, stderr = popen.communicate()
-            self.assertRegex(stdout, expected_error)
+                popen = script_helper.spawn_python('-m', 'main', cwd=tmp)
+                stdout, stderr = popen.communicate()
+                self.assertRegex(stdout, expected_error)
 
-            # and there's no shadowing at all when using -P
-            popen = script_helper.spawn_python('-P', 'main.py', cwd=tmp)
-            stdout, stderr = popen.communicate()
-            self.assertRegex(stdout, b"module 'fractions' has no attribute 'shadowing_module'")
+                # and there's no shadowing at all when using -P
+                popen = script_helper.spawn_python('-P', 'main.py', cwd=tmp)
+                stdout, stderr = popen.communicate()
+                self.assertRegex(stdout, b"module 'fractions' has no attribute 'shadowing_module'")
 
     def test_script_shadowing_third_party(self):
-        with os_helper.temp_dir() as tmp:
-            with open(os.path.join(tmp, "numpy.py"), "w", encoding='utf-8') as f:
-                f.write("import numpy\nnumpy.array")
-
-            expected_error = (
-                rb"AttributeError: module 'numpy' has no attribute 'array' "
-                rb"\(consider renaming '.*numpy.py' if it has the "
-                rb"same name as a third-party module you intended to import\)\s+\Z"
+        script_errors = [
+            (
+                "import numpy\nnumpy.array",
+                rb"AttributeError: module 'numpy' has no attribute 'array'"
+            ),
+            (
+                "from numpy import array",
+                rb"ImportError: cannot import name 'array' from 'numpy'"
             )
+        ]
+        for script, error in script_errors:
+            with self.subTest(script=script), os_helper.temp_dir() as tmp:
+                with open(os.path.join(tmp, "numpy.py"), "w", encoding='utf-8') as f:
+                    f.write(script)
+
+                expected_error = error + (
+                    rb" \(consider renaming '.*numpy.py' if it has the "
+                    rb"same name as a library you intended to import\)\s+\Z"
+                )
 
-            popen = script_helper.spawn_python(os.path.join(tmp, "numpy.py"))
-            stdout, stderr = popen.communicate()
-            self.assertRegex(stdout, expected_error)
+                popen = script_helper.spawn_python(os.path.join(tmp, "numpy.py"))
+                stdout, stderr = popen.communicate()
+                self.assertRegex(stdout, expected_error)
 
-            popen = script_helper.spawn_python('-m', 'numpy', cwd=tmp)
-            stdout, stderr = popen.communicate()
-            self.assertRegex(stdout, expected_error)
+                popen = script_helper.spawn_python('-m', 'numpy', cwd=tmp)
+                stdout, stderr = popen.communicate()
+                self.assertRegex(stdout, expected_error)
 
-            popen = script_helper.spawn_python('-c', 'import numpy', cwd=tmp)
-            stdout, stderr = popen.communicate()
-            self.assertRegex(stdout, expected_error)
+                popen = script_helper.spawn_python('-c', 'import numpy', cwd=tmp)
+                stdout, stderr = popen.communicate()
+                self.assertRegex(stdout, expected_error)
 
     def test_script_maybe_not_shadowing_third_party(self):
         with os_helper.temp_dir() as tmp:
@@ -911,15 +940,23 @@ fractions.Fraction
             expected_error = (
                 rb"AttributeError: module 'numpy' has no attribute 'attr'\s+\Z"
             )
-
             popen = script_helper.spawn_python('-c', 'import numpy; numpy.attr', cwd=tmp)
             stdout, stderr = popen.communicate()
             self.assertRegex(stdout, expected_error)
 
+            expected_error = (
+                rb"ImportError: cannot import name 'attr' from 'numpy' \(.*\)\s+\Z"
+            )
+            popen = script_helper.spawn_python('-c', 'from numpy import attr', cwd=tmp)
+            stdout, stderr = popen.communicate()
+            self.assertRegex(stdout, expected_error)
+
     def test_script_shadowing_stdlib_edge_cases(self):
         with os_helper.temp_dir() as tmp:
             with open(os.path.join(tmp, "fractions.py"), "w", encoding='utf-8') as f:
                 f.write("shadowing_module = True")
+
+            # Unhashable str subclass
             with open(os.path.join(tmp, "main.py"), "w", encoding='utf-8') as f:
                 f.write("""
 import fractions
@@ -932,11 +969,28 @@ try:
 except TypeError as e:
     print(str(e))
 """)
+            popen = script_helper.spawn_python("main.py", cwd=tmp)
+            stdout, stderr = popen.communicate()
+            self.assertEqual(stdout.rstrip(), b"unhashable type: 'substr'")
+
+            with open(os.path.join(tmp, "main.py"), "w", encoding='utf-8') as f:
+                f.write("""
+import fractions
+fractions.shadowing_module
+class substr(str):
+    __hash__ = None
+fractions.__name__ = substr('fractions')
+try:
+    from fractions import Fraction
+except TypeError as e:
+    print(str(e))
+""")
 
             popen = script_helper.spawn_python("main.py", cwd=tmp)
             stdout, stderr = popen.communicate()
             self.assertEqual(stdout.rstrip(), b"unhashable type: 'substr'")
 
+            # Various issues with sys module
             with open(os.path.join(tmp, "main.py"), "w", encoding='utf-8') as f:
                 f.write("""
 import fractions
@@ -961,18 +1015,45 @@ try:
 except AttributeError as e:
     print(str(e))
 """)
+            popen = script_helper.spawn_python("main.py", cwd=tmp)
+            stdout, stderr = popen.communicate()
+            lines = stdout.splitlines()
+            self.assertEqual(len(lines), 3)
+            for line in lines:
+                self.assertEqual(line, b"module 'fractions' has no attribute 'Fraction'")
 
+            with open(os.path.join(tmp, "main.py"), "w", encoding='utf-8') as f:
+                f.write("""
+import fractions
+fractions.shadowing_module
+
+import sys
+sys.stdlib_module_names = None
+try:
+    from fractions import Fraction
+except ImportError as e:
+    print(str(e))
+
+del sys.stdlib_module_names
+try:
+    from fractions import Fraction
+except ImportError as e:
+    print(str(e))
+
+sys.path = [0]
+try:
+    from fractions import Fraction
+except ImportError as e:
+    print(str(e))
+""")
             popen = script_helper.spawn_python("main.py", cwd=tmp)
             stdout, stderr = popen.communicate()
-            self.assertEqual(
-                stdout.splitlines(),
-                [
-                    b"module 'fractions' has no attribute 'Fraction'",
-                    b"module 'fractions' has no attribute 'Fraction'",
-                    b"module 'fractions' has no attribute 'Fraction'",
-                ],
-            )
+            lines = stdout.splitlines()
+            self.assertEqual(len(lines), 3)
+            for line in lines:
+                self.assertRegex(line, rb"cannot import name 'Fraction' from 'fractions' \(.*\)")
 
+            # Various issues with origin
             with open(os.path.join(tmp, "main.py"), "w", encoding='utf-8') as f:
                 f.write("""
 import fractions
@@ -992,37 +1073,61 @@ except AttributeError as e:
 
             popen = script_helper.spawn_python("main.py", cwd=tmp)
             stdout, stderr = popen.communicate()
-            self.assertEqual(
-                stdout.splitlines(),
-                [
-                    b"module 'fractions' has no attribute 'Fraction'",
-                    b"module 'fractions' has no attribute 'Fraction'"
-                ],
-            )
-
-    def test_script_shadowing_stdlib_sys_path_modification(self):
-        with os_helper.temp_dir() as tmp:
-            with open(os.path.join(tmp, "fractions.py"), "w", encoding='utf-8') as f:
-                f.write("shadowing_module = True")
-
-            expected_error = (
-                rb"AttributeError: module 'fractions' has no attribute 'Fraction' "
-                rb"\(consider renaming '.*fractions.py' since it has the "
-                rb"same name as the standard library module named 'fractions' "
-                rb"and the import system gives it precedence\)"
-            )
+            lines = stdout.splitlines()
+            self.assertEqual(len(lines), 2)
+            for line in lines:
+                self.assertEqual(line, b"module 'fractions' has no attribute 'Fraction'")
 
             with open(os.path.join(tmp, "main.py"), "w", encoding='utf-8') as f:
                 f.write("""
-import sys
-sys.path.insert(0, "this_folder_does_not_exist")
 import fractions
-fractions.Fraction
-""")
+fractions.shadowing_module
+del fractions.__spec__.origin
+try:
+    from fractions import Fraction
+except ImportError as e:
+    print(str(e))
 
+fractions.__spec__.origin = 0
+try:
+    from fractions import Fraction
+except ImportError as e:
+    print(str(e))
+""")
             popen = script_helper.spawn_python("main.py", cwd=tmp)
             stdout, stderr = popen.communicate()
-            self.assertRegex(stdout, expected_error)
+            lines = stdout.splitlines()
+            self.assertEqual(len(lines), 2)
+            for line in lines:
+                self.assertRegex(line, rb"cannot import name 'Fraction' from 'fractions' \(.*\)")
+
+    def test_script_shadowing_stdlib_sys_path_modification(self):
+        script_errors = [
+            (
+                "import fractions\nfractions.Fraction",
+                rb"AttributeError: module 'fractions' has no attribute 'Fraction'"
+            ),
+            (
+                "from fractions import Fraction",
+                rb"ImportError: cannot import name 'Fraction' from 'fractions'"
+            )
+        ]
+        for script, error in script_errors:
+            with self.subTest(script=script), os_helper.temp_dir() as tmp:
+                with open(os.path.join(tmp, "fractions.py"), "w", encoding='utf-8') as f:
+                    f.write("shadowing_module = True")
+                with open(os.path.join(tmp, "main.py"), "w", encoding='utf-8') as f:
+                    f.write('import sys; sys.path.insert(0, "this_folder_does_not_exist")\n')
+                    f.write(script)
+                expected_error = error + (
+                    rb" \(consider renaming '.*fractions.py' since it has the "
+                    rb"same name as the standard library module named 'fractions' "
+                    rb"and prevents importing that standard library module\)"
+                )
+
+                popen = script_helper.spawn_python("main.py", cwd=tmp)
+                stdout, stderr = popen.communicate()
+                self.assertRegex(stdout, expected_error)
 
 
 @skip_if_dont_write_bytecode

diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2024-09-11-01-32-07.gh-issue-123930.BkPfB6.rst b/Misc/NEWS.d/next/Core_and_Builtins/2024-09-11-01-32-07.gh-issue-123930.BkPfB6.rst
new file mode 100644 (file)
index 0000000..3c8eb02
--- /dev/null
+++ b/Misc/NEWS.d/next/Core_and_Builtins/2024-09-11-01-32-07.gh-issue-123930.BkPfB6.rst
@@ -0,0 +1,4 @@
+Improve the error message when a script shadowing a module from the standard\r
+library causes :exc:`ImportError` to be raised during a "from" import.\r
+Similarly, improve the error message when a script shadowing a third party module\r
+attempts to "from" import an attribute from that third party module while still initialising.

diff --git a/Objects/moduleobject.c b/Objects/moduleobject.c
index c06badd5f3edfe74271688d1624c1534a28cb8e8..535b0d068f064f030cd2410c0afb110f3c67140a 100644 (file)
--- a/Objects/moduleobject.c
+++ b/Objects/moduleobject.c
@@ -836,15 +836,15 @@ _PyModuleSpec_IsUninitializedSubmodule(PyObject *spec, PyObject *name)
     return rc;
 }
 
-static int
-_get_file_origin_from_spec(PyObject *spec, PyObject **p_origin)
+int
+_PyModuleSpec_GetFileOrigin(PyObject *spec, PyObject **p_origin)
 {
     PyObject *has_location = NULL;
     int rc = PyObject_GetOptionalAttr(spec, &_Py_ID(has_location), &has_location);
     if (rc <= 0) {
         return rc;
     }
-    // If origin is not a location, or doesn't exist, or is not a str), we could consider falling
+    // If origin is not a location, or doesn't exist, or is not a str, we could consider falling
     // back to module.__file__. But the cases in which module.__file__ is not __spec__.origin
     // are cases in which we probably shouldn't be guessing.
     rc = PyObject_IsTrue(has_location);
@@ -867,8 +867,8 @@ _get_file_origin_from_spec(PyObject *spec, PyObject **p_origin)
     return 1;
 }
 
-static int
-_is_module_possibly_shadowing(PyObject *origin)
+int
+_PyModule_IsPossiblyShadowing(PyObject *origin)
 {
     // origin must be a unicode subtype
     // Returns 1 if the module at origin could be shadowing a module of the
@@ -993,11 +993,11 @@ _Py_module_getattro_impl(PyModuleObject *m, PyObject *name, int suppress)
     }
 
     PyObject *origin = NULL;
-    if (_get_file_origin_from_spec(spec, &origin) < 0) {
+    if (_PyModuleSpec_GetFileOrigin(spec, &origin) < 0) {
         goto done;
     }
 
-    int is_possibly_shadowing = _is_module_possibly_shadowing(origin);
+    int is_possibly_shadowing = _PyModule_IsPossiblyShadowing(origin);
     if (is_possibly_shadowing < 0) {
         goto done;
     }
@@ -1018,20 +1018,23 @@ _Py_module_getattro_impl(PyModuleObject *m, PyObject *name, int suppress)
                     "module '%U' has no attribute '%U' "
                     "(consider renaming '%U' since it has the same "
                     "name as the standard library module named '%U' "
-                    "and the import system gives it precedence)",
+                    "and prevents importing that standard library module)",
                     mod_name, name, origin, mod_name);
     }
     else {
         int rc = _PyModuleSpec_IsInitializing(spec);
-        if (rc > 0) {
+        if (rc < 0) {
+            goto done;
+        }
+        else if (rc > 0) {
             if (is_possibly_shadowing) {
                 assert(origin);
-                // For third-party modules, only mention the possibility of
+                // For non-stdlib modules, only mention the possibility of
                 // shadowing if the module is being initialized.
                 PyErr_Format(PyExc_AttributeError,
                             "module '%U' has no attribute '%U' "
                             "(consider renaming '%U' if it has the same name "
-                            "as a third-party module you intended to import)",
+                            "as a library you intended to import)",
                             mod_name, name, origin);
             }
             else if (origin) {
@@ -1049,7 +1052,8 @@ _Py_module_getattro_impl(PyModuleObject *m, PyObject *name, int suppress)
                             mod_name, name);
             }
         }
-        else if (rc == 0) {
+        else {
+            assert(rc == 0);
             rc = _PyModuleSpec_IsUninitializedSubmodule(spec, name);
             if (rc > 0) {
                 PyErr_Format(PyExc_AttributeError,

diff --git a/Python/ceval.c b/Python/ceval.c
index ece7ef1d32048fe5d3ff7d43da5127871f30ada4..beee5325cd62591b2757d44e5514f6f35d4f45e1 100644 (file)
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -2802,7 +2802,7 @@ PyObject *
 _PyEval_ImportFrom(PyThreadState *tstate, PyObject *v, PyObject *name)
 {
     PyObject *x;
-    PyObject *fullmodname, *pkgname, *pkgpath, *pkgname_or_unknown, *errmsg;
+    PyObject *fullmodname, *mod_name, *origin, *mod_name_or_unknown, *errmsg, *spec;
 
     if (PyObject_GetOptionalAttr(v, name, &x) != 0) {
         return x;
@@ -2810,16 +2810,16 @@ _PyEval_ImportFrom(PyThreadState *tstate, PyObject *v, PyObject *name)
     /* Issue #17636: in case this failed because of a circular relative
        import, try to fallback on reading the module directly from
        sys.modules. */
-    if (PyObject_GetOptionalAttr(v, &_Py_ID(__name__), &pkgname) < 0) {
+    if (PyObject_GetOptionalAttr(v, &_Py_ID(__name__), &mod_name) < 0) {
         return NULL;
     }
-    if (pkgname == NULL || !PyUnicode_Check(pkgname)) {
-        Py_CLEAR(pkgname);
+    if (mod_name == NULL || !PyUnicode_Check(mod_name)) {
+        Py_CLEAR(mod_name);
         goto error;
     }
-    fullmodname = PyUnicode_FromFormat("%U.%U", pkgname, name);
+    fullmodname = PyUnicode_FromFormat("%U.%U", mod_name, name);
     if (fullmodname == NULL) {
-        Py_DECREF(pkgname);
+        Py_DECREF(mod_name);
         return NULL;
     }
     x = PyImport_GetModule(fullmodname);
@@ -2827,63 +2827,121 @@ _PyEval_ImportFrom(PyThreadState *tstate, PyObject *v, PyObject *name)
     if (x == NULL && !_PyErr_Occurred(tstate)) {
         goto error;
     }
-    Py_DECREF(pkgname);
+    Py_DECREF(mod_name);
     return x;
+
  error:
-    if (pkgname == NULL) {
-        pkgname_or_unknown = PyUnicode_FromString("<unknown module name>");
-        if (pkgname_or_unknown == NULL) {
+    if (mod_name == NULL) {
+        mod_name_or_unknown = PyUnicode_FromString("<unknown module name>");
+        if (mod_name_or_unknown == NULL) {
             return NULL;
         }
     } else {
-        pkgname_or_unknown = pkgname;
+        mod_name_or_unknown = mod_name;
     }
+    // mod_name is no longer an owned reference
+    assert(mod_name_or_unknown);
+    assert(mod_name == NULL || mod_name == mod_name_or_unknown);
 
-    pkgpath = NULL;
-    if (PyModule_Check(v)) {
-        pkgpath = PyModule_GetFilenameObject(v);
-        if (pkgpath == NULL) {
-            if (!PyErr_ExceptionMatches(PyExc_SystemError)) {
-                Py_DECREF(pkgname_or_unknown);
-                return NULL;
+    origin = NULL;
+    if (PyObject_GetOptionalAttr(v, &_Py_ID(__spec__), &spec) < 0) {
+        Py_DECREF(mod_name_or_unknown);
+        return NULL;
+    }
+    if (spec == NULL) {
+        errmsg = PyUnicode_FromFormat(
+            "cannot import name %R from %R (unknown location)",
+            name, mod_name_or_unknown
+        );
+        goto done_with_errmsg;
+    }
+    if (_PyModuleSpec_GetFileOrigin(spec, &origin) < 0) {
+        goto done;
+    }
+
+    int is_possibly_shadowing = _PyModule_IsPossiblyShadowing(origin);
+    if (is_possibly_shadowing < 0) {
+        goto done;
+    }
+    int is_possibly_shadowing_stdlib = 0;
+    if (is_possibly_shadowing) {
+        PyObject *stdlib_modules = PySys_GetObject("stdlib_module_names");
+        if (stdlib_modules && PyAnySet_Check(stdlib_modules)) {
+            is_possibly_shadowing_stdlib = PySet_Contains(stdlib_modules, mod_name_or_unknown);
+            if (is_possibly_shadowing_stdlib < 0) {
+                goto done;
             }
-            // module filename missing
-            _PyErr_Clear(tstate);
         }
     }
-    if (pkgpath == NULL || !PyUnicode_Check(pkgpath)) {
-        Py_CLEAR(pkgpath);
+
+    if (is_possibly_shadowing_stdlib) {
+        assert(origin);
         errmsg = PyUnicode_FromFormat(
-            "cannot import name %R from %R (unknown location)",
-            name, pkgname_or_unknown
+            "cannot import name %R from %R "
+            "(consider renaming %R since it has the same "
+            "name as the standard library module named %R "
+            "and prevents importing that standard library module)",
+            name, mod_name_or_unknown, origin, mod_name_or_unknown
         );
     }
     else {
-        PyObject *spec;
-        int rc = PyObject_GetOptionalAttr(v, &_Py_ID(__spec__), &spec);
-        if (rc > 0) {
-            rc = _PyModuleSpec_IsInitializing(spec);
-            Py_DECREF(spec);
-        }
+        int rc = _PyModuleSpec_IsInitializing(spec);
         if (rc < 0) {
-            Py_DECREF(pkgname_or_unknown);
-            Py_DECREF(pkgpath);
-            return NULL;
+            goto done;
+        }
+        else if (rc > 0) {
+            if (is_possibly_shadowing) {
+                assert(origin);
+                // For non-stdlib modules, only mention the possibility of
+                // shadowing if the module is being initialized.
+                errmsg = PyUnicode_FromFormat(
+                    "cannot import name %R from %R "
+                    "(consider renaming %R if it has the same name "
+                    "as a library you intended to import)",
+                    name, mod_name_or_unknown, origin
+                );
+            }
+            else if (origin) {
+                errmsg = PyUnicode_FromFormat(
+                    "cannot import name %R from partially initialized module %R "
+                    "(most likely due to a circular import) (%S)",
+                    name, mod_name_or_unknown, origin
+                );
+            }
+            else {
+                errmsg = PyUnicode_FromFormat(
+                    "cannot import name %R from partially initialized module %R "
+                    "(most likely due to a circular import)",
+                    name, mod_name_or_unknown
+                );
+            }
+        }
+        else {
+            assert(rc == 0);
+            if (origin) {
+                errmsg = PyUnicode_FromFormat(
+                    "cannot import name %R from %R (%S)",
+                    name, mod_name_or_unknown, origin
+                );
+            }
+            else {
+                errmsg = PyUnicode_FromFormat(
+                    "cannot import name %R from %R (unknown location)",
+                    name, mod_name_or_unknown
+                );
+            }
         }
-        const char *fmt =
-            rc ?
-            "cannot import name %R from partially initialized module %R "
-            "(most likely due to a circular import) (%S)" :
-            "cannot import name %R from %R (%S)";
-
-        errmsg = PyUnicode_FromFormat(fmt, name, pkgname_or_unknown, pkgpath);
     }
-    /* NULL checks for errmsg and pkgname done by PyErr_SetImportError. */
-    _PyErr_SetImportErrorWithNameFrom(errmsg, pkgname, pkgpath, name);
 
-    Py_XDECREF(errmsg);
-    Py_DECREF(pkgname_or_unknown);
-    Py_XDECREF(pkgpath);
+done_with_errmsg:
+    /* NULL checks for errmsg, mod_name, origin done by PyErr_SetImportError. */
+    _PyErr_SetImportErrorWithNameFrom(errmsg, mod_name, origin, name);
+    Py_DECREF(errmsg);
+
+done:
+    Py_XDECREF(origin);
+    Py_XDECREF(spec);
+    Py_DECREF(mod_name_or_unknown);
     return NULL;
 }
 
@@ -3243,5 +3301,3 @@ _PyEval_LoadName(PyThreadState *tstate, _PyInterpreterFrame *frame, PyObject *na
     }
     return value;
 }
-
-