Better error for fallback of vectorize_node with non-tensor types

pytensor/tensor/blockwise.py

@@ -14,9 +14,10 @@ from pytensor.graph.replace import (
     _vectorize_not_needed,
     vectorize_graph,
 )
+from pytensor.scalar import ScalarType
 from pytensor.tensor import as_tensor_variable
 from pytensor.tensor.shape import shape_padleft
-from pytensor.tensor.type import continuous_dtypes, discrete_dtypes, tensor
+from pytensor.tensor.type import TensorType, continuous_dtypes, discrete_dtypes, tensor
 from pytensor.tensor.utils import (
     _parse_gufunc_signature,
     broadcast_static_dim_lengths,
@@ -373,6 +374,12 @@ class Blockwise(Op):
 
 @_vectorize_node.register(Op)
 def vectorize_node_fallback(op: Op, node: Apply, *bached_inputs) -> Apply:
+    for inp in node.inputs:
+        if not isinstance(inp.type, (TensorType, ScalarType)):
+            raise NotImplementedError(
+                f"Cannot vectorize node {node} with input {inp} of type {inp.type}"
+            )
+
     if hasattr(op, "gufunc_signature"):
         signature = op.gufunc_signature
     else:

tests/tensor/test_blockwise.py

+import re
 from itertools import product
 from typing import Optional, Union
 
@@ -12,7 +13,7 @@ from pytensor.graph import Apply, Op
 from pytensor.graph.replace import vectorize_node
 from pytensor.raise_op import assert_op
 from pytensor.tensor import diagonal, log, tensor
-from pytensor.tensor.blockwise import Blockwise
+from pytensor.tensor.blockwise import Blockwise, vectorize_node_fallback
 from pytensor.tensor.nlinalg import MatrixInverse
 from pytensor.tensor.rewriting.blas import specialize_matmul_to_batched_dot
 from pytensor.tensor.slinalg import Cholesky, Solve, cholesky, solve_triangular
@@ -42,6 +43,19 @@ def test_vectorize_blockwise():
     assert new_vect_node.inputs[0] is tns4
 
 
+def test_vectorize_node_fallback_unsupported_type():
+    x = tensor("x", shape=(2, 6))
+    node = x[:, [0, 2, 4]].owner
+
+    with pytest.raises(
+        NotImplementedError,
+        match=re.escape(
+            "Cannot vectorize node AdvancedSubtensor(x, MakeSlice.0, [0 2 4]) with input MakeSlice.0 of type slice"
+        ),
+    ):
+        vectorize_node_fallback(node.op, node, node.inputs)
+
+
 def check_blockwise_runtime_broadcasting(mode):
     a = tensor("a", shape=(None, 3, 5))
     b = tensor("b", shape=(None, 5, 3))