ENH: torch.reshape: implement copy with Torch view and clone operations

src/array_api_compat/torch/_aliases.py

@@ -585,15 +585,19 @@ def where(condition: Array, x1: Array | complex, x2: Array | complex, /) -> Arra
     return torch.where(condition, x1, x2)
 
 
-# torch.reshape doesn't have the copy keyword
 def reshape(x: Array,
             /,
             shape: tuple[int, ...],
             *,
             copy: bool | None = None,
             **kwargs: object) -> Array:
-    if copy is not None:
-        raise NotImplementedError("torch.reshape doesn't yet support the copy keyword")
+    if copy is True:
+        return x.clone(memory_format=torch.contiguous_format).view(shape, **kwargs)
+    if copy is False:
+        try:
+            return x.view(shape, **kwargs)
+        except RuntimeError as error:
+            raise ValueError(str(error)) from error
     return torch.reshape(x, shape, **kwargs)
 
 # torch.arange doesn't support returning empty arrays

tests/test_torch.py

@@ -12,6 +12,21 @@
 from array_api_compat import torch as xp
 
 
+def test_reshape_copy():
+    array = xp.arange(12).reshape((3, 4))
+
+    view = xp.reshape(array, (4, 3), copy=False)
+    view[0, 0] = -1
+    assert array[0, 0] == -1
+
+    with pytest.raises(ValueError):
+        xp.reshape(array.T, (12,), copy=False)
+
+    copied = xp.reshape(array, (4, 3), copy=True)
+    copied[0, 0] = -2
+    assert array[0, 0] == -1
+
+
 class TestResultType:
     def test_empty(self):
         with pytest.raises(ValueError):