conflict error after install: Unable to activate twee2-0.5.0, because bundler-2.1.4 conflicts with bundler (~> 1.6)

[phivk]

After I install twee2 via

gem install twee2

I get the following ConflictError:

$ twee2
Traceback (most recent call last):
        7: from /Users/phivk/.rvm/gems/ruby-2.6.0/bin/ruby_executable_hooks:22:in `<main>'
        6: from /Users/phivk/.rvm/gems/ruby-2.6.0/bin/ruby_executable_hooks:22:in `eval'
        5: from /Users/phivk/.rvm/gems/ruby-2.6.0/bin/twee2:23:in `<main>'
        4: from /Users/phivk/.rvm/rubies/ruby-2.6.0/lib/ruby/site_ruby/2.6.0/rubygems.rb:304:in `activate_bin_path'
        3: from /Users/phivk/.rvm/rubies/ruby-2.6.0/lib/ruby/site_ruby/2.6.0/rubygems.rb:304:in `synchronize'
        2: from /Users/phivk/.rvm/rubies/ruby-2.6.0/lib/ruby/site_ruby/2.6.0/rubygems.rb:305:in `block in activate_bin_path'
        1: from /Users/phivk/.rvm/rubies/ruby-2.6.0/lib/ruby/site_ruby/2.6.0/rubygems/specification.rb:1415:in `activate'
/Users/phivk/.rvm/rubies/ruby-2.6.0/lib/ruby/site_ruby/2.6.0/rubygems/specification.rb:2298:in `raise_if_conflicts': Unable to activate twee2-0.5.0, because bundler-2.1.4 conflicts with bundler (~> 1.6) (Gem::ConflictError)

As you can see from the logs above, I have ruby 2.6.0 installed via RVM.

I am not super familiar with the Ruby Gem ecosystem. Is there a way to downgrade bundler-2.1.4 to match ~> 1.6 or upgrade the other way around?

[tmilker]

Just edit twee2.gemspec and change the line:

spec.add_runtime_dependency 'bundler', '~> 1.6'

to

spec.add_runtime_dependency 'bundler', '~> 2.1'

The reason why it's a runtime dependency isn't jumping out at me because the require 'bundler/setup' in lib/twee2.rb doesn't seem to be used.

edit: Whoops, was in dev mode and forgot you were just trying to install the gem, not build it. The instructions would require building the gem yourself and installing that. You could also make a new folder and a Gemfile and put:

gem 'twee2', path: '/path/to/your/copy/of/twee2/repo/with/change/above'

and run bundle install