Do not remove TF NodeDef attributes under enable_lvar_defaults

The `NodeDef` attributes of a "Const" operator hold the distinguishing constant
value, so removing them results in a meta object that no longer corresponds to a
specific constant.

Author: brandonwillard

symbolic_pymc/tensorflow/meta.py

@@ -407,7 +407,7 @@ class TFlowMetaNodeDef(TFlowMetaSymbol):
     def _metatize(cls, obj):
         res = super()._metatize(obj)
 
-        if "node_attrs" in meta._lvar_defaults_enabled:
+        if obj.op != "Const" and "node_attrs" in meta._lvar_defaults_enabled:
             res.attr = var()
 
         if "names" in meta._lvar_defaults_enabled:

tests/tensorflow/test_meta.py

@@ -594,6 +594,10 @@ def test_global_options():
         assert isvar(b_mt.op.node_def.attr)
         assert b_mt.op.inputs[1] is a_mt
 
+        # `NodeDef.attr` for constants should not be turned into lvars
+        assert not isvar(b_mt.op.inputs[0].op.node_def.attr)
+        assert not isvar(b_mt.op.inputs[1].op.node_def.attr)
+
     # Make sure we clear out the `.obj` so that the names won't mismatch
     with tf.Graph().as_default(), enable_lvar_defaults('names'):
         a_mt = mt(1.0)