special handling for ^<att>

[garfieldnate]

This production will never validate against any datamap:

sp {foo
   (state <s> ^name <name>)
-->
   (<s> ^<name> name)
}

The problem is the creation of the dynamically-named attribute ^<name> in the RHS. DM validation would have to be made more advanced to do any real checking here:

• enumerate the possible values for
• iterate over those values and check each against the DM

This could get very expensive for dynamic attributes that have deep sub-structures that possibly contain more dynamic attributes.

For now, I would like to just update the DM feedback for this case:

could not match constraint (<s>,<name>,name) in production

This is the same exact message that's used for any other validation error. This error should be more of a warning saying that V-S is not able to validate the attribute, rather than an error that the attribute is invalid.