cannot load such file -- ffi on windows

[ahorek]

after this change #132

ffi gem isn't part of the gemspec anymore and bundler doesn't require such dependencies

require 'ffi' will raise an error LoadError: cannot load such file -- ffi even if the gem is actually installed

backtrace

LoadError: cannot load such file -- ffi
C:/Ruby25-x64/lib/ruby/gems/2.5.0/gems/childprocess-1.0.1/lib/childprocess/windows.rb:1:in `require'
C:/Ruby25-x64/lib/ruby/gems/2.5.0/gems/childprocess-1.0.1/lib/childprocess/windows.rb:1:in `'
C:/Ruby25-x64/lib/ruby/gems/2.5.0/gems/childprocess-1.0.1/lib/childprocess.rb:209:in `require'
C:/Ruby25-x64/lib/ruby/gems/2.5.0/gems/childprocess-1.0.1/lib/childprocess.rb:209:in `'
C:/Ruby25-x64/lib/ruby/gems/2.5.0/gems/selenium-webdriver-3.142.1/lib/selenium/webdriver.rb:20:in `require'
C:/Ruby25-x64/lib/ruby/gems/2.5.0/gems/selenium-webdriver-3.142.1/lib/selenium/webdriver.rb:20:in `'
C:/Ruby25-x64/lib/ruby/gems/2.5.0/gems/selenium-webdriver-3.142.1/lib/selenium-webdriver.rb:20:in `require'
C:/Ruby25-x64/lib/ruby/gems/2.5.0/gems/selenium-webdriver-3.142.1/lib/selenium-webdriver.rb:20:in `'
C:/Ruby25-x64/lib/ruby/gems/2.5.0/gems/bundler-1.17.3/lib/bundler/runtime.rb:81:in `require'
C:/Ruby25-x64/lib/ruby/gems/2.5.0/gems/bundler-1.17.3/lib/bundler/runtime.rb:81:in `block (2 levels) in require'
C:/Ruby25-x64/lib/ruby/gems/2.5.0/gems/bundler-1.17.3/lib/bundler/runtime.rb:76:in `each'
C:/Ruby25-x64/lib/ruby/gems/2.5.0/gems/bundler-1.17.3/lib/bundler/runtime.rb:76:in `block in require'
C:/Ruby25-x64/lib/ruby/gems/2.5.0/gems/bundler-1.17.3/lib/bundler/runtime.rb:65:in `each'
C:/Ruby25-x64/lib/ruby/gems/2.5.0/gems/bundler-1.17.3/lib/bundler/runtime.rb:65:in `require'
C:/Ruby25-x64/lib/ruby/gems/2.5.0/gems/bundler-1.17.3/lib/bundler.rb:114:in `require'
c:/redmine/config/application.rb:7:in `'
C:/Ruby25-x64/lib/ruby/site_ruby/2.5.0/rubygems/core_ext/kernel_require.rb:59:in `require'
C:/Ruby25-x64/lib/ruby/site_ruby/2.5.0/rubygems/core_ext/kernel_require.rb:59:in `require'
c:/redmine/Rakefile:5:in `'
C:/Ruby25-x64/lib/ruby/gems/2.5.0/gems/rake-12.3.2/lib/rake/rake_module.rb:29:in `load'
C:/Ruby25-x64/lib/ruby/gems/2.5.0/gems/rake-12.3.2/lib/rake/rake_module.rb:29:in `load_rakefile'
C:/Ruby25-x64/lib/ruby/gems/2.5.0/gems/rake-12.3.2/lib/rake/application.rb:703:in `raw_load_rakefile'
C:/Ruby25-x64/lib/ruby/gems/2.5.0/gems/rake-12.3.2/lib/rake/application.rb:104:in `block in load_rakefile'
C:/Ruby25-x64/lib/ruby/gems/2.5.0/gems/rake-12.3.2/lib/rake/application.rb:186:in `standard_exception_handling'
C:/Ruby25-x64/lib/ruby/gems/2.5.0/gems/rake-12.3.2/lib/rake/application.rb:103:in `load_rakefile'
C:/Ruby25-x64/lib/ruby/gems/2.5.0/gems/rake-12.3.2/lib/rake/application.rb:82:in `block in run'
C:/Ruby25-x64/lib/ruby/gems/2.5.0/gems/rake-12.3.2/lib/rake/application.rb:186:in `standard_exception_handling'
C:/Ruby25-x64/lib/ruby/gems/2.5.0/gems/rake-12.3.2/lib/rake/application.rb:80:in `run'
C:/Ruby25-x64/lib/ruby/gems/2.5.0/gems/rake-12.3.2/exe/rake:27:in `'
C:/Ruby25-x64/bin/rake:23:in `load'
C:/Ruby25-x64/bin/rake:23:in `'

if I add gem 'ffi' into app's Gemfile it works fine, but I think that childprocess should require it as a dependency, not just install the gem under the hood.

[sds]

Hey @ahorek, what does Gem.win_platform? return for you?

The gem should install the ffi gem on Windows automatically. See:

childprocess/ext/mkrf_conf.rb

Lines 14 to 16 in 982b1ae

	if Gem.win_platform?
	inst.install 'ffi', Gem::Requirement.new('~> 1.0', '>= 1.0.11')
	end

[sds]

Sorry, I misread your comment.

This is likely because you are running your application via Bundler. With Bundler, your LOAD_PATH is changed based on whatever gems are explicitly listed in your Gemfile. There's nothing childprocess can do about this—you need to configure your Gemfile appropriately if you are going to be running your application via bundle exec or similar.

Hope that helps!

[ahorek]

You're right, but I also don't have gem 'childprocess' in my Gemfile explicitly, other gems depend on it. The same way 'ffi' should be a runtime dependency of 'childprocess'.
It's no big deal for me and the workaround works.

[sds]

Ah, understood. This is an unfortunate case, but there are good reasons we don't include the ffi gem by default, which are described in the PR you reference. Most users don't need it, and installing a gem that requires native extensions to be built increases install time substantially.

Whichever gems are depending on childprocess should also be including an explicit dependency on ffi if they want to support Windows. Suggest you open an issue on those gems.

[sds]

Following up here to say we've removed the magic ffi install logic in #160. Recommend you always include ffi as a dependency in your Gemfile going forward. This will be shipped in ChildProcess 3.0.0. Thanks!