Fix constants in macro expressions to be referenced from the top level

[maiha]

Referencing Crystal in a macro conflicts with user-defined Crystal.

module Jewel
  class Crystal
    delegate to_s, to: self.class
  end
end

puts Jewel::Crystal.new

$ crystal --version
Crystal 1.13.1 [405f313e0] (2024-07-12)

$ crystal jewel.cr
In crystal/src/object.cr:1296:28

 1296 | {% if compare_versions(Crystal::VERSION, "1.12.0-dev") >= 0 %}
                               ^---------------
Error: undefined constant Crystal::VERSION

It works correctly with earlier versions of Crystal or this PR.

$ crystal jewel.cr
Jewel::Crystal

This fix was created mechanically by

sed -i -e 's/compare_versions(Crystal/compare_versions(::Crystal/g' **/*.cr(^/)

Best regards,

[straight-shoota]

This seems unnecessary for top-level code which always evaluates in the scope where its defined. It might still be good to use the same style everywhere... However, there are other top-level constants in macro expressions. So we should look at those as well.

[ysbaddaden]

Thanks for finding this and for the fix!

Only the macro delegated fix is necessary because the macro is injecting code into other places. The other fixes don't inject code and there won't be conflicts.

I'd prefer to avoid prefixing :: everywhere for no reason.

I'd rather have an analysis of other macros that inject code (getter, setter, etc) at uncontrolled places and fix potentially clashing namespaces.