fix: delegate no-copy reshape to namespace

Author: stanbot8

src/array_api_compat/common/_aliases.py

@@ -444,6 +444,10 @@ def permute_dims(x: Array, /, axes: tuple[int, ...], xp: Namespace) -> Array:
     return xp.transpose(x, axes)
 
 
+def _reshape_supports_copy(xp: Namespace) -> bool:
+    return "copy" in inspect.signature(xp.reshape).parameters
+
+
 # np.reshape calls the keyword argument 'newshape' instead of 'shape'
 def reshape(
     x: Array,
@@ -457,6 +461,8 @@ def reshape(
     if copy is True:
         x = x.copy()
     elif copy is False:
+        if _reshape_supports_copy(xp):
+            return xp.reshape(x, shape, copy=False, **kwargs)
         y = x.view()
         y.shape = shape
         return y

tests/test_common.py

@@ -1,4 +1,5 @@
 import math
+import warnings
 
 import pytest
 import numpy as np
@@ -17,6 +18,7 @@
 from array_api_compat import (
     device, is_array_api_obj, is_lazy_array, is_writeable_array, size, to_device
 )
+from array_api_compat.common._aliases import reshape
 from array_api_compat.common._helpers import _DASK_DEVICE
 from ._helpers import all_libraries, import_, wrapped_libraries, xfail
 
@@ -376,3 +378,18 @@ def test_clip_out(library):
     xp.clip(x, 15, 25, out=out)
     expect = xp.asarray([15, 20, 25])
     assert xp.all(out == expect)
+
+
+def test_reshape_copy_false_returns_a_view_without_deprecation():
+    x = np.arange(12)
+    with warnings.catch_warnings():
+        warnings.simplefilter("error", DeprecationWarning)
+        y = reshape(x, (3, 4), xp=np, copy=False)
+
+    assert y.shape == (3, 4)
+    assert np.shares_memory(x, y)
+
+
+def test_reshape_copy_false_rejects_an_input_that_needs_a_copy():
+    with pytest.raises((ValueError, AttributeError)):
+        reshape(np.arange(12).reshape(3, 4).T, (2, 6), xp=np, copy=False)