ENH: Schedule int64 warning to convert to error at 5.0

Author: effigies

nibabel/nifti1.py

@@ -21,6 +21,7 @@
 from .arrayproxy import get_obj_dtype
 from .batteryrunners import Report
 from .casting import have_binary128
+from .deprecated import alert_future_error
 from .filebasedimages import SerializableImage
 from .optpkg import optional_package
 from .quaternions import fillpositive, mat2quat, quat2mat
@@ -1831,13 +1832,16 @@ def __init__(self, dataobj, affine, header=None, extra=None, file_map=None, dtyp
         # already fail.
         danger_dts = (np.dtype('int64'), np.dtype('uint64'))
         if header is None and dtype is None and get_obj_dtype(dataobj) in danger_dts:
-            msg = (
+            alert_future_error(
                 f'Image data has type {dataobj.dtype}, which may cause '
-                'incompatibilities with other tools. This will error in '
-                'NiBabel 5.0. This warning can be silenced '
-                f'by passing the dtype argument to {self.__class__.__name__}().'
+                'incompatibilities with other tools.',
+                '5.0',
+                warning_rec='This warning can be silenced by passing the dtype argument'
+                f' to {self.__class__.__name__}().',
+                error_rec='To use this type, pass an explicit header or dtype argument'
+                f' to {self.__class__.__name__}().',
+                error_class=ValueError,
             )
-            warnings.warn(msg, FutureWarning, stacklevel=2)
         super().__init__(dataobj, affine, header, extra, file_map, dtype)
         # Force set of s/q form when header is None unless affine is also None
         if header is None and affine is not None:

nibabel/tests/test_nifti1.py

@@ -35,6 +35,7 @@
     slice_order_codes,
 )
 from nibabel.optpkg import optional_package
+from nibabel.pkg_info import cmp_pkg_version
 from nibabel.spatialimages import HeaderDataError
 from nibabel.tmpdirs import InTemporaryDirectory
 
@@ -766,16 +767,21 @@ class TestNifti1Pair(tana.TestAnalyzeImage, tspm.ImageScalingMixin):
     image_class = Nifti1Pair
     supported_np_types = TestNifti1PairHeader.supported_np_types
 
-    def test_int64_warning(self):
+    def test_int64_warning_or_error(self):
         # Verify that initializing with (u)int64 data and no
-        # header/dtype info produces a warning
+        # header/dtype info produces a warning/error
         img_klass = self.image_class
         hdr_klass = img_klass.header_class
         for dtype in (np.int64, np.uint64):
             data = np.arange(24, dtype=dtype).reshape((2, 3, 4))
-            with pytest.warns(FutureWarning):
+            # Starts as a warning, transitions to error at 5.0
+            if cmp_pkg_version('5.0') < 0:
+                cm = pytest.raises(ValueError)
+            else:
+                cm = pytest.warns(FutureWarning)
+            with cm:
                 img_klass(data, np.eye(4))
-            # No warnings if we're explicit, though
+            # No problems if we're explicit, though
             with clear_and_catch_warnings():
                 warnings.simplefilter('error')
                 img_klass(data, np.eye(4), dtype=dtype)