Fix failure in change_dist_size when RVs don't take dtype argument

Author: Chirag3841

pymc/distributions/shape_utils.py

@@ -305,8 +305,7 @@ def change_rv_size(op, rv, new_size, expand) -> TensorVariable:
     # to not unnecessarily pick up a `Cast` in some cases (see #4652).
     new_size = pt.as_tensor(new_size, ndim=1, dtype="int64")
 
-    new_rv = rv_node.op(*dist_params, size=new_size, dtype=rv.type.dtype)
-
+    new_rv = rv_node.op(*dist_params, size=new_size)
     # Replicate "traditional" rng default_update, if that was set for old_rng
     default_update = getattr(old_rng, "default_update", None)
     if default_update is not None:

tests/sampling/test_forward.py

@@ -35,6 +35,7 @@
 import pymc as pm
 
 from pymc.backends.base import MultiTrace
+from pymc.distributions.shape_utils import change_dist_size
 from pymc.model.transform.optimization import freeze_dims_and_data
 from pymc.pytensorf import compile, rvs_in_graph
 from pymc.sampling.forward import (
@@ -1979,3 +1980,12 @@ def test_vectorize_over_posterior_with_intermediate_rvs():
     assert np.array_equiv(a_ancestor1.eval(), idata.posterior.a.data)
     assert isinstance(a_ancestor2, TensorConstant)
     assert np.array_equiv(a_ancestor2.eval(), idata.posterior.a.data)
+
+
+def test_change_dist_size_zero_sum_normal():
+    with pm.Model():
+        intercept = pm.ZeroSumNormal("intercept", sigma=1.0, shape=2)
+
+    resized = change_dist_size(intercept, new_size=(10,), expand=True)
+
+    assert resized.type.shape == (10, 2)