The Ruby DSL has been deprecated since several 3x versions back and should be removed in 4.0.
The future parser/evaluator does not support it at all.
There are places in the logic where it is checked if the code of an AST is "ruby_code" and it takes a different path. This should be removed. The 3x AST still needs to be intact in 4.0.0 since not all expressions are evaluated by the new evaluator - but the ruby support should be removed.
The Ruby DSL implementation can then be deleted from the codebase together with its tests.