Loosen the self-type constraint for Net::HTTPHeader

[hibariya]

Net::HTTPHeader could be included by classes that do not inherit ::Object and we need to loosen the self-type constraint.

For example, HTTParty::Response::Headers, which includes Net::HTTPHeader, inherits SimpleDelegator < Delegator < BasicObject. With the current definition, it causes an error like below:

/workspaces/gem_rbs_collection/gems/httparty/0.18/_test/.gem_rbs_collection/httparty/0.18/httparty.rbs:453:6: [error] Module self type constraint in type `::HTTParty::Response::Headers` doesn't satisfy: `::HTTParty::Response::Headers <: ::Object`
│ Diagnostic ID: RBS::ModuleSelfTypeError
│
└       include Net::HTTPHeader
        ~~~~~~~~~~~~~~~~~~~~~~~

Note that to reproduce the error above, you need to modify the manifest.yml like below:

diff --git a/gems/httparty/0.18/manifest.yaml b/gems/httparty/0.18/manifest.yaml
index a5128c3..8d0d7ab 100644
--- a/gems/httparty/0.18/manifest.yaml
+++ b/gems/httparty/0.18/manifest.yaml
@@ -1,3 +1,4 @@
 dependencies:
   - name: uri
   - name: net-http
+  - name: delegate

I also considered defining an interface instead of using BasicObject at first, but it seems the following syntax is illegal.

interface _HasHeader
  @header: Hash[String,  untyped]
end

[ParadoxV5]

Should top be the default self constraint for all modules?

[soutaro]

👍

[soutaro]

I don't think changing the default of self-constraint to top makes sense.
Instead, we may want to consider allowing instance variables in interfaces. (But what does interface mean then?)

[ParadoxV5]

But what does interface mean then?

a shape? which might detail instance vars and constants as well as methods?