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[3.13] gh-123930: Better error for "from imports" when script shadows module (GH-123929) (#125937)

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

(cherry picked from commit 500f5338a8)
This commit is contained in:
Shantanu 2024-10-24 12:37:31 -07:00 • committed by GitHub
parent 4b55d53316
commit 3d8b6f0977
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GPG key ID: B5690EEEBB952194
6 changed files with 344 additions and 171 deletions
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150
Python/ceval.c
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@ -2708,7 +2708,7 @@ static PyObject *
import_from(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;
@ -2716,16 +2716,16 @@ import_from(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);
@ -2733,63 +2733,121 @@ import_from(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;
}
// module filename missing
_PyErr_Clear(tstate);
}
origin = NULL;
if (PyObject_GetOptionalAttr(v, &_Py_ID(__spec__), &spec) < 0) {
Py_DECREF(mod_name_or_unknown);
return NULL;
}
if (pkgpath == NULL || !PyUnicode_Check(pkgpath)) {
Py_CLEAR(pkgpath);
if (spec == NULL) {
errmsg = PyUnicode_FromFormat(
"cannot import name %R from %R (unknown location)",
name, pkgname_or_unknown
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;
}
}
}
if (is_possibly_shadowing_stdlib) {
assert(origin);
errmsg = PyUnicode_FromFormat(
"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;
}