Move warning about 2021.12 to set_array_api_strict_flags()

Author: asmeurer

array_api_strict/_array_object.py

@@ -17,7 +17,6 @@
 
 import operator
 from enum import IntEnum
-import warnings
 
 from ._creation_functions import asarray
 from ._dtypes import (
@@ -502,8 +501,6 @@ def __array_namespace__(
 
         """
         set_array_api_strict_flags(api_version=api_version)
-        if api_version == "2021.12":
-            warnings.warn("The 2021.12 version of the array API specification was requested but the returned namespace is actually version 2022.12")
         import array_api_strict
         return array_api_strict
 

array_api_strict/_flags.py

@@ -13,6 +13,7 @@
 
 import functools
 import os
+import warnings
 
 import array_api_strict
 
@@ -62,6 +63,9 @@ def set_array_api_strict_flags(
       versions are: ``{supported_versions}``. The default version number is
       ``{default_version!r}``.
 
+      Note that 2021.12 is supported, but currently gives the same thing as
+      2022.12 (except that the fft extension will be disabled).
+
     - `data_dependent_shapes`: Whether data-dependent shapes are enabled in
       array-api-strict.
 
@@ -118,6 +122,8 @@ def set_array_api_strict_flags(
     if api_version is not None:
         if api_version not in supported_versions:
             raise ValueError(f"Unsupported standard version {api_version!r}")
+        if api_version == "2021.12":
+            warnings.warn("The 2021.12 version of the array API specification was requested but the returned namespace is actually version 2022.12")
         API_VERSION = api_version
         array_api_strict.__array_api_version__ = API_VERSION
 

array_api_strict/tests/test_flags.py

@@ -32,8 +32,12 @@ def test_flags():
         'data_dependent_shapes': False,
         'enabled_extensions': ('fft',),
     }
-    # Make sure setting the version to 2021.12 disables fft
-    set_array_api_strict_flags(api_version='2021.12')
+    # Make sure setting the version to 2021.12 disables fft and issues a
+    # warning.
+    with pytest.warns(UserWarning) as record:
+        set_array_api_strict_flags(api_version='2021.12')
+    assert len(record) == 1
+    assert '2021.12' in str(record[0].message)
     flags = get_array_api_strict_flags()
     assert flags == {
         'api_version': '2021.12',
@@ -51,10 +55,11 @@ def test_flags():
         enabled_extensions=('linalg', 'fft')))
 
     # Test resetting flags
-    set_array_api_strict_flags(
-        api_version='2021.12',
-        data_dependent_shapes=False,
-        enabled_extensions=())
+    with pytest.warns(UserWarning):
+        set_array_api_strict_flags(
+            api_version='2021.12',
+            data_dependent_shapes=False,
+            enabled_extensions=())
     reset_array_api_strict_flags()
     flags = get_array_api_strict_flags()
     assert flags == {