Remove unnecessary graph_inputs usage in OpFromGraph

Author: brandonwillard

pytensor/compile/builders.py

@@ -344,21 +344,23 @@ def __init__(
                 if isinstance(i, SharedVariable):
                     raise TypeError(f"SharedVariables not allowed as inputs; {i}")
 
-        for var in graph_inputs(outputs, inputs):
-            if var not in inputs and not isinstance(var, (Constant, SharedVariable)):
-                raise MissingInputError(f"OpFromGraph is missing an input: {var}")
-
         if "updates" in kwargs or "givens" in kwargs:
-            raise NotImplementedError("Updates and givens are not allowed here")
+            raise NotImplementedError("Updates and givens are not supported")
 
         self.is_inline = inline
 
-        # To correctly support shared variables the inner fct should
-        # not see them. Otherwise there is a problem with the gradient.
         self.shared_inputs = []
-        for var in graph_inputs(outputs):
+        inner_graph_inputs = graph_inputs(outputs, inputs)
+        for var in inner_graph_inputs:
             if isinstance(var, SharedVariable):
+                # To correctly support shared variables the inner-graph should
+                # not see them; otherwise, there will be problems with
+                # gradients.
+                # That's why we collect the shared variables and replace them
+                # with dummies.
                 self.shared_inputs.append(var)
+            elif var not in inputs and not isinstance(var, Constant):
+                raise MissingInputError(f"OpFromGraph is missing an input: {var}")
 
         inputs, outputs = replace_nominals_with_dummies(inputs, outputs)