DSL AST initialisation recursively searches up namespaces for consts

[invke]

When the DSL AST initialises nodes, it performs a .const_get on the relative module. This has problems, as it will look recursively up the entire module tree for a relating const that it will then instantiate.

For example, in method_missing on Elasticsearch::DSL::Search::Query line 39, it calls const_defined? and const_get on Queries. If you happen to have say, a class defined in the root namespace called Report and you call report, it'll find this class, make a new instance and give it to you. This creates some strangeness with the other conditional, where it defers to binding to allow you to access methods in the outer context.

I am using the DSL to dynamically create queries, often using instances of this model, which I have sensibly named report in the context I am using the DSL. However, when the arity == 0, and I try to access this report, it hits the const_defined? and initializes a new instance of ::Report.

class Report
end

class Example
  include Elasticsearch::DSL
  
  attr_accessor :report
  
  def initialize(report)
    @report = report
  end
  
  def generate_query
    search do
      query do
        # Now anywhere in here report will be a Report.new everytime, instead of deferring to the outer caller's report.
      end
      aggregation :wicked_metric do
        # Similarly here, the same issue arises.
      end
    end
  end
end

I don't believe this is the intended behavior, or if it is intended, perhaps ensuring the found class is within the Elasticsearch::DSL::Search namespace would be sufficient safety.

Queries.const_defined? klass, false

I can just use the arity to prevent the issue, but that's pretty ugly on larger queries and creates a lot of clutter.