Avoiding "already initialized constant errors" with net/protocol

[stanhu]

If I have a gem that depends on net/imap v0.2.1, I see that it conflicts with the Ruby interpreter's version:

$ bundle exec rspec spec
/home/travis/.rvm/rubies/ruby-2.6.6/lib/ruby/2.6.0/net/protocol.rb:66: warning: already initialized constant Net::ProtocRetryError
/home/travis/.rvm/gems/ruby-2.6.6/gems/net-protocol-0.1.0/lib/net/protocol.rb:66: warning: previous definition of ProtocRetryError was here
/home/travis/.rvm/rubies/ruby-2.6.6/lib/ruby/2.6.0/net/protocol.rb:206: warning: already initialized constant Net::BufferedIO::BUFSIZE
/home/travis/.rvm/gems/ruby-2.6.6/gems/net-protocol-0.1.0/lib/net/protocol.rb:206: warning: previous definition of BUFSIZE was here
/home/travis/.rvm/rubies/ruby-2.6.6/lib/ruby/2.6.0/net/protocol.rb:503: warning: already initialized constant Net::NetPrivate::Socket
/home/travis/.rvm/gems/ruby-2.6.6/gems/net-protocol-0.1.0/lib/net/protocol.rb:503: warning: previous definition of Socket was here

Is there a way this updated version of the gem can be used as a separate dependency without generating these warnings? https://stackoverflow.com/a/9117903/1992201 has some suggestions, but these still seem like hacks. Does it make sense to remove net/protocol as a hard dependency? MRI appears to have an exact copy of protocol.rb.

[shugo]

net/protocol and net/imap have been default gems since Ruby 3.0, so it may introduce problems to remove net-protocol from dependencies.
On Ruby 2.6, net/imap itself is not a (default) gem, so it may be hard to use the net-imap gem without hacks.

@hsbt What do you think?

[deivid-rodriguez]

@stanhu I'm interested in this is issue. Can you share steps to reproduce the warnings?

[stanhu]

@deivid-rodriguez The easiest way I've been able to reproduce it:

git clone git@github.com:tpitale/mail_room.git
cd mail_room
echo 2.7.2 > .ruby_version # Choose your version
bundle install
bundle exec rspec spec/lib/mailbox_spec.rb

[deivid-rodriguez]

Thanks, I'll have a look!

[deivid-rodriguez]

The proper fix here in my opinion would be that the faraday-net_http gem would declare the net-http gem as a dependency.

This is the explanation of what's happening:

• When the faraday-net_http gem is required, it then requires net/http.
• Then the stdlib version of net/http is loaded, since bundler doesn't know net-http is a gem dependency, so it doesn't add the gemified version to to the $LOAD_PATH.
• Then the stdlib version of net/http requires net/protocol relatively, since that's what it used to happen before these gems were gemified. See ruby/net-http@6da598e. So the stdlib version of net/protocol is loaded.
• Then when net-imap is required, it also uses net-protocol but this time the gemified version of net-protocol is used, because net-imap properly declares it as a dependency, so bundler knows about it and has put it in the $LOAD_PATH. This is what causes the double load of net/protocol.

If faraday-net_http explicitly declares net-http as a dependency, then the gemified version of all gems involved will be consistently loaded and there will be no redefinition warnings.

I suggest that you proposed this update to faraday-net_http and in the mean time, you can workaround this issue by adding gem "net-http" to your Gemfile.

[stanhu]

@deivid-rodriguez Thanks for that tip! That seems to work well. I've submitted lostisland/faraday-net_http#5 and tpitale/mail_room#123.