Issue #26129: Deprecated accepting non-integers in grp.getgrgid().

Doc/library/grp.rst

@@ -42,6 +42,9 @@ It defines the following items:
    Return the group database entry for the given numeric group ID. :exc:`KeyError`
    is raised if the entry asked for cannot be found.
 
+   .. deprecated:: 3.6
+      Since Python 3.6 the support of non-integer arguments like floats or
+      strings in :func:`getgrgid` is deprecated.
 
 .. function:: getgrnam(name)
 

Lib/test/test_grp.py

@@ -92,5 +92,15 @@ class GroupDatabaseTestCase(unittest.TestCase):
 
         self.assertRaises(KeyError, grp.getgrgid, fakegid)
 
+    def test_noninteger_gid(self):
+        entries = grp.getgrall()
+        if not entries:
+            self.skipTest('no groups')
+        # Choose an existent gid.
+        gid = entries[0][2]
+        self.assertWarns(DeprecationWarning, grp.getgrgid, float(gid))
+        self.assertWarns(DeprecationWarning, grp.getgrgid, str(gid))
+
+
 if __name__ == "__main__":
     unittest.main()

Misc/NEWS

@@ -131,6 +131,8 @@ Core and Builtins
 Library
 -------
 
+- Issue #26129: Deprecated accepting non-integers in grp.getgrgid().
+
 - Issue #25850: Use cross-compilation by default for 64-bit Windows.
 
 - Issue #25822: Add docstrings to the fields of urllib.parse results.

Modules/grpmodule.c

@@ -100,6 +100,16 @@ grp_getgrgid_impl(PyModuleDef *module, PyObject *id)
     gid_t gid;
     struct group *p;
 
+    if (!_Py_Gid_Converter(id, &gid)) {
+        if (!PyErr_ExceptionMatches(PyExc_TypeError)) {
+            return NULL;
+        }
+        PyErr_Clear();
+        if (PyErr_WarnFormat(PyExc_DeprecationWarning, 1,
+                             "group id must be int, not %.200",
+                             id->ob_type->tp_name) < 0) {
+            return NULL;
+        }
         py_int_id = PyNumber_Long(id);
         if (!py_int_id)
             return NULL;
@@ -108,6 +118,7 @@ grp_getgrgid_impl(PyModuleDef *module, PyObject *id)
             return NULL;
         }
         Py_DECREF(py_int_id);
+    }
 
     if ((p = getgrgid(gid)) == NULL) {
         PyObject *gid_obj = _PyLong_FromGid(gid);