Reverts dffac29e63de6a51047fe77cf9d553ab762ef19b

PiperOrigin-RevId: 678748794

CHANGELOG.md

@@ -16,6 +16,16 @@ When releasing, please add the new-release-boilerplate to docs/pallas/CHANGELOG.
   * This release includes wheels for Python 3.13. Free-threading mode is not yet
     supported.
 
+* Breaking changes
+  * `jax_pmap_no_rank_reduction` flag is set to `True` by default.
+    * array[0] on a pmap result now introduces a reshape (use array[0:1]
+      instead).
+    * The per-shard shape (accessable via jax_array.addressable_shards or
+      jax_array.addressable_data(0)) now has a leading (1, ...). Update code
+      that directly accesses shards accordingly. The rank of the per-shard-shape
+      now matches that of the global shape which is the same behavior as jit.
+      This avoids costly reshapes when passing results from pmap into jit.
+
 * Deprecations
   * In {func}`jax.numpy.trim_zeros`, non-arraylike arguments or arraylike
     arguments with `ndim != 1` are now deprecated, and in the future will result
@@ -34,6 +44,11 @@ When releasing, please add the new-release-boilerplate to docs/pallas/CHANGELOG.
       `jax.jit(fn).trace(*args, **kwargs).lower(lowering_platforms=('tpu',)).compiler_ir('hlo')`.
   * {class}`jax.ShapeDtypeStruct` no longer accepts the `named_shape` argument.
     The argument was only used by `xmap` which was removed in 0.4.31.
+  * `jax.tree.map(f, None, non-None)`, which previously emitted a
+    `DeprecationWarning`, now raises an error in a future version of jax. `None`
+    is only a tree-prefix of itself. To preserve the current behavior, you can
+    ask `jax.tree.map` to treat `None` as a leaf value by writing:
+    `jax.tree.map(lambda x, y: None if x is None else f(x, y), a, b, is_leaf=lambda x: x is None)`.
 
 * Bug fixes
   * Fixed a bug where {func}`jax.numpy.cumsum` would produce incorrect outputs
@@ -62,14 +77,6 @@ See the 0.4.33 release notes for more details.
     C++ and CUDA code from JAX.
 
 * Changes
-  * `jax_pmap_no_rank_reduction` flag is set to `True` by default.
-    * array[0] on a pmap result now introduces a reshape (use array[0:1]
-      instead).
-    * The per-shard shape (accessable via jax_array.addressable_shards or
-      jax_array.addressable_data(0)) now has a leading (1, ...). Update code
-      that directly accesses shards accordingly. The rank of the per-shard-shape
-      now matches that of the global shape which is the same behavior as jit.
-      This avoids costly reshapes when passing results from pmap into jit.
   * `jax_enable_memories` flag is set to `True` by default.
   * {mod}`jax.numpy` now supports v2023.12 of the Python Array API Standard.
     See {ref}`python-array-api` for more information.

tests/tree_util_test.py

@@ -24,6 +24,7 @@ from absl.testing import parameterized
 import jax
 from jax import flatten_util
 from jax import tree_util
+from jax._src.lib import xla_extension_version
 from jax._src import test_util as jtu
 from jax._src.tree_util import flatten_one_level, prefix_errors
 import jax.numpy as jnp
@@ -395,6 +396,7 @@ class TreeTest(jtu.JaxTestCase):
       ({"a": 1, "b": (2, 3)}, {"a": [7], "b": ([8], (9,))}, [[7], [8], (9,)]),
       ({"a": 1}, {"a": (7,)}, [(7,)]),
       ({"a": 1}, {"a": {"a": 7}}, [{"a": 7}]),
+      (None, None, [])
   )
   def testFlattenUpTo(self, tree, xs, expected):
     _, tree_def = tree_util.tree_flatten(tree)
@@ -483,6 +485,11 @@ class TreeTest(jtu.JaxTestCase):
           [([1], (2,), {"a": [1]})],
           re.escape("Custom node type mismatch"),
       ),
+      *(
+          []
+          if xla_extension_version < 288
+          else [(None, [2], re.escape("Expected None, got [2]."))]
+      ),
   )
   def testFlattenUpToErrors(self, tree, xs, error):
     _, tree_def = tree_util.tree_flatten(tree)