Fix UDP binding rules

systemrdl/core/ComponentVisitor.py

@@ -624,8 +624,9 @@ def visitNormal_prop_assign(self, ctx:SystemRDLParser.Normal_prop_assignContext)
         if ctx.prop_assignment_rhs() is not None:
             rhs = self.visit(ctx.prop_assignment_rhs())
         else:
-            # No RHS implies "true" assignment
-            rhs = True
+            # No explicit RHS
+            # What this implies is resolved later
+            rhs = None
 
         return SourceRef.from_antlr(prop_token), prop_name, rhs
 

systemrdl/core/properties.py

@@ -85,6 +85,11 @@ def assign_value(self, comp_def, value, src_ref):
                 src_ref
             )
 
+        # Property assignments with no rhs show up as None here
+        # For built-in properties, this implies a True value
+        if value is None:
+            value = True
+
         # unpack true type of value
         # Contents of value can be:
         #   - implied "true" assignment (bool literal, True)
@@ -1109,7 +1114,24 @@ def __init__(self, env, name, bindable_to, valid_types, default = None, constr_c
 
     def get_name(self):
         return self.name
+
+
+    def assign_value(self, comp_def, value, src_ref):
+        # Property assignments with no rhs show up as None here
+        # For user-defined properties, this implies the default value
+        # (15.2.2)
+        if value is None:
+            value = self.default
+
+        super().assign_value(comp_def, value, src_ref)
+
+    def get_default(self, node):
+        # pylint: disable=unused-argument
 
+        # If a user-defined property is not explicitly assigned, then it
+        # does not get bound with its default value
+        return None
+
     def validate(self, node, value):
         if self.constr_componentwidth:
             # 15.1.1-g: If constraint is set to componentwidth, the assigned