warning: already initialized constant StringScanner::Version

[dabroz]

When using this gem with ruby 3.3.1 I'm getting

.../.rbenv/versions/3.3.1/lib/ruby/gems/3.3.0/gems/strscan-3.1.0/lib/strscan.bundle: warning: already initialized constant StringScanner::Version

[kou]

Could you provide a way to reproduce this?

[kinsomicrote]

I am also seeing the same thing on my Rails project:

.../.asdf/installs/ruby/3.3.0/lib/ruby/gems/3.3.0/gems/strscan-3.1.0/lib/strscan.bundle: warning: already initialized constant StringScanner::Version
.../.asdf/installs/ruby/3.3.0/lib/ruby/gems/3.3.0/gems/strscan-3.1.0/lib/strscan.bundle: warning: already initialized constant StringScanner::Id

I get this when I run my test suite - rspec. In my Rails project, strscan is used by rexml which is used by rubocop.

[dabroz]

I've created a minified version of the project here: https://github.com/dabroz/strscantest To see this behaviour, clone the repo, then run bundle; rspec test.rb There is also a Dockerfile you can test wit h./dockme

But the strangest thing is that there have to be very specific circumstances to observe this problem:

• only with Ruby 3.3
• only directly on Mac, not on Linux via Docker
• only when using bootsnap
• only when using rbenv
• only when running rspec via shim (when running bundle exec rspec it works fine)

[kou]

Thanks for preparing a minified project.

Why do you want to use rspec not bundle exec rspec? In general, you should use bundle exec ... when you use Gemfile to manage your dependency.

[dabroz]

Overall sure, but this happens even on a clean rbenv install, where only gems are the ones installed from the Gemfile.

[kou]

Could you show gem list output on the reproduced environment?

[dabroz]

Bingo!

strscan (3.1.0, default: 3.0.7)

After pinning it:

gem 'strscan', '3.0.7'

it doesn't show the warning anymore. I had to pin rubocop to an earlier version (1.63.0) as the latest requires the latest strscan:

    rubocop was resolved to 1.64.0, which depends on
      rexml (>= 3.2.5, < 4.0) was resolved to 3.2.8, which depends on
        strscan (>= 3.0.9)

So can we do anything if a newer version of a default gem is needed?

[kou]

The next REXML version that includes https://github.com/ruby/rexml/issues/132 will change the situation. It relaxes required strscan version. (But bundle exec rspec is still preferred.)

[Soeren-Klatt]

Got the same message when running only rspec without bundle exec. The message appeared after going from ruby 3.1.6 to ruby 3.2.0. Im using strscan (3.1.0)

[kou]

If gem list | grep strscan has multiple versions, you must use bundle exec to choose only one strscan.