BUG: make _like functions raise if array arg dtype is incompatible with the device

Author: ev-br

array_api_strict/_creation_functions.py

@@ -168,6 +168,8 @@ def empty_like(
     _check_device(device)
     if device is None:
         device = x.device
+    if dtype is None:
+        dtype = x.dtype
     _check_valid_dtype(dtype, device)
 
     return Array._new(np.empty_like(x._array, dtype=_np_dtype(dtype)), device=device)
@@ -279,6 +281,8 @@ def full_like(
     _check_device(device)
     if device is None:
         device = x.device
+    if dtype is None:
+        dtype = x.dtype
     _check_valid_dtype(dtype, device)
 
     if not isinstance(fill_value, bool | int | float | complex):
@@ -384,6 +388,8 @@ def ones_like(
     _check_device(device)
     if device is None:
         device = x.device
+    if dtype is None:
+        dtype = x.dtype
     _check_valid_dtype(dtype, device)
 
     return Array._new(np.ones_like(x._array, dtype=_np_dtype(dtype)), device=device)
@@ -451,6 +457,8 @@ def zeros_like(
     _check_device(device)
     if device is None:
         device = x.device
+    if dtype is None:
+        dtype = x.dtype
     _check_valid_dtype(dtype, device)
 
     return Array._new(np.zeros_like(x._array, dtype=_np_dtype(dtype)), device=device)

array_api_strict/tests/test_creation_functions.py

@@ -263,8 +263,17 @@ def test_ones_like_etc_incorrect(self, func):
         # >>> torch.ones_like(a, device='mps')
         # TypeError: Cannot convert a MPS Tensor to float64 dtype as the MPS framework
         # doesn't support float64.
-        with pytest.raises(TypeError):
+
+        # incompatible dtype inferred from `a.dtype`
+        with pytest.raises((TypeError, ValueError)):
             func(a, device=Device('F32_device'))
+
+        # `a.dtype` is compatible but the explicit dtype= argument is incompatible
+        a = ones(2, dtype=float32)
+        with pytest.raises((TypeError, ValueError)):
+            func(a, device=Device('F32_device'), dtype=float64)
+
+
 # TODO:
 # def asarray(
 # def arange(