numpy · ngoldbaum · May 17, 2024 · May 16, 2024 · May 16, 2024 · May 16, 2024
diff --git a/doc/release/upcoming_changes/26452.deprecation.rst b/doc/release/upcoming_changes/26452.deprecation.rst
@@ -0,0 +1,4 @@
+  * The `fix_imports` keyword argument in `numpy.save` is deprecated. Since
+    NumPy 1.17, `numpy.save` uses a pickle protocol that no longer supports
+    Python 2, and ignored `fix_imports` keyword. This keyword is kept only
+    for backward compatibility. It is now deprecated.
diff --git a/numpy/_core/tests/test_deprecations.py b/numpy/_core/tests/test_deprecations.py
@@ -14,7 +14,7 @@
 import numpy as np
 from numpy.testing import (
     assert_raises, assert_warns, assert_, assert_array_equal, SkipTest,
-    KnownFailureException, break_cycles,
+    KnownFailureException, break_cycles, temppath
     )
 
 from numpy._core._multiarray_tests import fromstring_null_term_c_api
@@ -716,3 +716,26 @@ class TestDeprecatedDTypeParenthesizedRepeatCount(_DeprecationTestCase):
     @pytest.mark.parametrize("string", ["(2)i,", "(3)3S,", "f,(2)f"])
     def test_parenthesized_repeat_count(self, string):
         self.assert_deprecated(np.dtype, args=(string,))
+
+
+class TestDeprecatedSaveFixImports(_DeprecationTestCase):
+    # Deprecated in Numpy 2.1, 2024-05
+    message = "The 'fix_imports' flag is deprecated and has no effect."
+
+    def test_deprecated(self):
+        with temppath(suffix='.npy') as path:
+            sample_args = (path, np.array(np.zeros((1024, 10))))
+            self.assert_not_deprecated(np.save, args=sample_args)
+            self.assert_deprecated(np.save, args=sample_args,
+                                kwargs={'fix_imports': True})
+            self.assert_deprecated(np.save, args=sample_args,
+                                kwargs={'fix_imports': False})
+            for allow_pickle in [True, False]:
+                self.assert_not_deprecated(np.save, args=sample_args,
+                                        kwargs={'allow_pickle': allow_pickle})
+                self.assert_deprecated(np.save, args=sample_args,
+                                    kwargs={'allow_pickle': allow_pickle,
+                                            'fix_imports': True})
+                self.assert_deprecated(np.save, args=sample_args,
+                                    kwargs={'allow_pickle': allow_pickle,
+                                            'fix_imports': False})
diff --git a/numpy/lib/_npyio_impl.py b/numpy/lib/_npyio_impl.py
@@ -501,7 +501,7 @@ def _save_dispatcher(file, arr, allow_pickle=None, fix_imports=None):
 
 
 @array_function_dispatch(_save_dispatcher)
-def save(file, arr, allow_pickle=True, fix_imports=True):
+def save(file, arr, allow_pickle=True, fix_imports=np._NoValue):
     """
     Save an array to a binary file in NumPy ``.npy`` format.
 
@@ -523,10 +523,11 @@ def save(file, arr, allow_pickle=True, fix_imports=True):
         compatible between different versions of Python).
         Default: True
     fix_imports : bool, optional
-        Only useful in forcing objects in object arrays on Python 3 to be
-        pickled in a Python 2 compatible way. If `fix_imports` is True, pickle
-        will try to map the new Python 3 names to the old module names used in
-        Python 2, so that the pickle data stream is readable with Python 2.
+        The `fix_imports` flag is deprecated and has no effect.
+
+        .. deprecated:: 2.1
+            This flag is ignored since NumPy 1.17 and was only needed to
+            support loading some files in Python 2 written in Python 3.
 
     See Also
     --------
@@ -561,6 +562,12 @@ def save(file, arr, allow_pickle=True, fix_imports=True):
     >>> print(a, b)
     # [1 2] [1 3]
     """
+    if fix_imports is not np._NoValue:
+        # Deprecated 2024-05-16, NumPy 2.1
+        warnings.warn(
+            "The 'fix_imports' flag is deprecated and has no effect. "
+            "(Deprecated in NumPy 2.1)",
+            DeprecationWarning, stacklevel=2)
     if hasattr(file, 'write'):
         file_ctx = contextlib.nullcontext(file)
     else: