erb.gemspec - only add cgi dependency when RUBY_VERSION < 3.5

[MSP-Greg]

The gemspec for cgi was removed in Ruby head (3.5), and this is causing many problems. Unfortunately, many have been hidden.

Currently, https://github.com/ruby/ruby-dev-builder is failing, and has done so for 10 days, hence an older version is used in GHA CI. The failure is due to the command rdoc -v failing. See the 'CLI Test' step here.

The workflow hides the error, locally run:

/usr/local/lib/ruby/3.5.0+0/rubygems/specification.rb:1421:in 'block in Gem::Specification#activate_dependencies':
Could not find 'cgi' (>= 0.3.3) among 87 total gem(s) (Gem::MissingSpecError)

Also, a command line ruby -rerb -e "puts 'Success'" will fail.

[k0kubun]

gemspec can't actually have a conditional dependency because gemspec is evaulated when gem build is executed. When Ruby 3.4 builds this gem, it would always add cgi as a dependency. When Ruby 3.5 builds this gem, it would not add cgi as a dependency. So I can't merge this patch.

I understand that there's a cgi-related trouble in ruby-dev-builder, but this repository is not the right place to fix it. Given that cgi >= 0.3.3 definitely exists on rubygems.org, it's the fault of either rubygems or (the libdir of) CRuby. Please report it at an appropriate place.

[MSP-Greg]

gemspec can't actually have a conditional dependency because gemspec is evaulated when gem build is executed. When Ruby 3.4 builds this gem, it would always add cgi as a dependency. When Ruby 3.5 builds this gem, it would not add cgi as a dependency.

Sorry. I thought that was the case, but I saw the code immediately above.

Thought about using Gem.install...

[k0kubun]

That's a valid code because we indeed run gem build once with CRuby and once with JRuby.

However, we don't run gem build with different CRuby versions. What you're doing is different from it.