Refine int checks (a bit annoyingly).

Author: seberg

numpy/_core/src/multiarray/descriptor.c

@@ -2553,13 +2553,21 @@ arraydescr_new(PyTypeObject *subtype,
         /*
          * In the future, reject non Python (or NumPy) boolean, including integers to avoid any
          * possibility of thinking that an integer alignment makes sense here.
+         * We omit the case of `oalign == 0` and `ocopy == 1` if there are exact ints.
+         * This can fail, in which case res is -1 and we enter the deprecation path.
          */
+        int res = 0;
+        int overflow;
         if (!PyBool_Check(oalign) && !PyArray_IsScalar(oalign, Bool) && !(
                 // Some old pickles use 0, 1 exactly, assume no user passes it
                 // (It may also be possible to use `copyreg` instead.)
-                PyLong_CheckExact(oalign) &&  PyLong_AsLong(oalign) == 0 &&
-                ocopy != NULL && PyLong_CheckExact(ocopy) && PyLong_AsLong(ocopy) == 1)) {
+                PyLong_CheckExact(oalign) && (res = PyLong_IsZero(oalign)) == 1 &&
+                ocopy != NULL && PyLong_CheckExact(ocopy) &&
+                (res = PyLong_AsLongAndOverflow(ocopy, &overflow)) == 1)) {
             /* Deprecated 2025-07-01: NumPy 2.4 */
+            if (res == -1 && PyErr_Occurred()) {
+                return NULL;  // Should actually be impossible (as inputs are `long`)
+            }
             if (PyErr_WarnFormat(npy_static_pydata.VisibleDeprecationWarning, 1,
                         "dtype(): align should be passed as Python or NumPy boolean but got `align=%.100R`. "
                         "Did you mean to pass a tuple to create a subarray type? (Deprecated NumPy 2.4)",

numpy/_core/tests/test_deprecations.py

@@ -280,11 +280,18 @@ def test_deprecated(self):
         # alignment, or pass them accidentally as a subarray shape (meaning to pass
         # a tuple).
         self.assert_deprecated(lambda: np.dtype("f8", align=3))
+        self.assert_deprecated(lambda: np.dtype("f8", align=0, copy=10**100))
+        self.assert_deprecated(lambda: np.dtype("f8", align=10**100, copy=0))
+        # Subclasses of ints don't hit the below pickle code path:
+        self.assert_deprecated(
+            lambda: np.dtype("f8", align=np.long(0), copy=np.long(1)))
 
     @pytest.mark.parametrize("align", [True, False, np.True_, np.False_])
     def test_not_deprecated(self, align):
         # if the user passes a bool, it is accepted.
         self.assert_not_deprecated(lambda: np.dtype("f8", align=align))
+        # The following specific case is used by old pickles:
+        self.assert_not_deprecated(lambda: np.dtype("f8", align=0, copy=1))
 
 
 class TestFlatiterIndexing0dBoolIndex(_DeprecationTestCase):