Bug #21645: Can't `require "resolve"` on Windows under Bundler without warnings

• Status: Assigned
• Assignee: hsbt (Hiroshi SHIBATA)
• Target version: -
• ruby -v: ruby 3.5.0dev (2025-10-19 master 957c832db1) +PRISM [x64-mingw-ucrt]
• Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN

[Earlopain (Earlopain _)]

prism had disabled some workflows for ruby-head on windows because of the extraction from fiddle to being a bundled gem.
I attempted to renable them now, but it is still an issue: https://github.com/ruby/prism/pull/3687

During bundle install, the mini_portile2 gem (to build nokogiri) ends up requiring net/http, which in turn requires resolv.
On windows, resolv requires win32/resolv here: https://github.com/ruby/ruby/blob/6eb75f6c36288cdd7522f27ad18608d13031f2b8/lib/resolv.rb#L1026-L1027. win32-registry depends on fiddle, and so under bundler it fails with the following:

D:/rubyinstaller-head-x64/lib/ruby/3.5.0+4/rubygems/specification.rb:1419:in
'block in Gem::Specification#activate_dependencies': Could not find 'fiddle' (~>
1.0) among 61 total gem(s) (Gem::MissingSpecError)
Checked in 'GEM_PATH=D:/a/prism/prism/vendor/bundle/ruby/3.5.0+4' at:
D:/rubyinstaller-head-x64/lib/ruby/gems/3.5.0+4/specifications/win32-registry-0.1.0.gemspec,
execute `gem env` for more information
from
D:/rubyinstaller-head-x64/lib/ruby/3.5.0+4/rubygems/specification.rb:1405:in
'Array#each'
from
D:/rubyinstaller-head-x64/lib/ruby/3.5.0+4/rubygems/specification.rb:1405:in
'Gem::Specification#activate_dependencies'
from
D:/rubyinstaller-head-x64/lib/ruby/3.5.0+4/rubygems/specification.rb:1387:in
'Gem::Specification#activate'
from
D:/rubyinstaller-head-x64/lib/ruby/3.5.0+4/rubygems/core_ext/kernel_gem.rb:62:in
'block in Kernel#gem'
from
D:/rubyinstaller-head-x64/lib/ruby/3.5.0+4/rubygems/core_ext/kernel_gem.rb:62:in
'Thread::Mutex#synchronize'
from
D:/rubyinstaller-head-x64/lib/ruby/3.5.0+4/rubygems/core_ext/kernel_gem.rb:62:in
'Kernel#gem'
from D:/rubyinstaller-head-x64/lib/ruby/3.5.0+4/resolv.rb:1026:in
'Kernel#require'
from D:/rubyinstaller-head-x64/lib/ruby/3.5.0+4/resolv.rb:1026:in
'Resolv::DNS::Config.default_config_hash'
from D:/rubyinstaller-head-x64/lib/ruby/3.5.0+4/resolv.rb:95:in
'Resolv#initialize'
from D:/rubyinstaller-head-x64/lib/ruby/3.5.0+4/resolv.rb:3469:in
'<class:Resolv>'
from D:/rubyinstaller-head-x64/lib/ruby/3.5.0+4/resolv.rb:35:in '<top
(required)>'
from D:/rubyinstaller-head-x64/lib/ruby/3.5.0+4/net/http.rb:25:in
'Kernel#require'
from D:/rubyinstaller-head-x64/lib/ruby/3.5.0+4/net/http.rb:25:in '<top
(required)>'
from
D:/a/prism/prism/vendor/bundle/ruby/3.5.0+4/gems/mini_portile2-2.8.9/lib/mini_portile2/mini_portile.rb:2:in
'Kernel#require'

I have tried to make a small reproduction by simply running bundle exec ruby -rresolv but there I just get a warning:

D:/rubyinstaller-head-x64/lib/ruby/3.5.0+4/win32/registry.rb:2: warning: fiddle/import is found in fiddle, which is not part of the default gems since Ruby 3.5.0.
You can add fiddle to your Gemfile or gemspec to fix this error.

I am not sure why that is. I feel like it should at the very least raise. But I don't have a windows machine to investigate this. Here is a github action run that shows this: https://github.com/Earlopain/test/actions/runs/18653590178/job/53177107372

There is also a github issue: https://github.com/ruby/win32-registry/issues/11

[Earlopain (Earlopain _)]

Here is a standalone workflow that demonstrates the issue closer to how I actually encountered it:

name: Test
on: push

jobs:
  make:
    runs-on: windows-latest

    steps:
    - run: echo "source 'https://rubygems.org'" >> Gemfile
    - run: echo "gem 'nokogiri'" >> Gemfile
    - name: Set up Ruby
      uses: ruby/setup-ruby@v1
      with:
        ruby-version: head
        bundler-cache: true

https://github.com/Earlopain/test/actions/runs/18682884097/job/53267891760

I tried adding fiddle to the gemfile to work around this, but I believe since this is happening during installation, doing that is not effective.

[mdalessio (Mike Dalessio)]

Would this problem be avoided if mini_portile2 declared an explicit dependency on net-http? If it would be helpful I'm happy to cut a new release of mini_portile with that change.

[Earlopain (Earlopain _)]

Thanks for popping in!

Would this problem be avoided if mini_portile2 declared an explicit dependency on net-http

No, that would not do much I think. The problem is that win32-registry is a default gem but it depends on fiddle which is not one anymore.

Actually I think this is supposed to be handled by https://github.com/ruby/ruby/commit/02a9c05e3ecc5b4a382ca9c7ca3e4adb79844bc2 and https://github.com/ruby/ruby/commit/a487698cc789624924ef5e309ffbffcc36f754ca but for some reason doing that doesn't really work under bundler.

[Eregon (Benoit Daloze)]

My impression here is we should always respect dependencies before changing from stdlib/default gem to bundled gem.

Concretely, I think fiddle shouldn't be a bundled gem before its stdlib & default gems usages (resolv, win32/resolv, win32-registry, etc) have become bundled gems before.

[hsbt (Hiroshi SHIBATA)]

• Status changed from Open to Assigned
• Assignee set to hsbt (Hiroshi SHIBATA)

It should fallback to pwsh implementation under bundle environment.

diff --git ext/win32/lib/win32/resolv.rb ext/win32/lib/win32/resolv.rb
index 226de7cba36..dae53baf118 100644
--- ext/win32/lib/win32/resolv.rb
+++ ext/win32/lib/win32/resolv.rb
@@ -58,7 +58,7 @@ def read_s(key)
         end
       end
       using SZ
-    rescue LoadError
+    rescue LoadError, Gem::MissingSpecError
       require "open3"
     end

Can you try the above patch? I don't have head version of mingw platform now.

[Earlopain (Earlopain _)]

I approximatly applied your patch with the following in github ci:

    - name: Patch
      run: (Get-Content D:/rubyinstaller-head-x64/lib/ruby/3.5.0+4/win32/resolv.rb).Replace('LoadError', 'LoadError, Gem::MissingSpecError') | Set-Content D:/rubyinstaller-head-x64/lib/ruby/3.5.0+4/win32/resolv.rb

It seems to work. I have a successful run with this here https://github.com/ruby/prism/actions/runs/18905343559/job/53962176814?pr=3687

[hsbt (Hiroshi SHIBATA)]

• Status changed from Assigned to Closed

Applied in changeset git|15f2dcceb4787c5738dde48f580019c3765ce1b8.

---

[ruby/resolv] Fallback to powershell implementation under the bundle environment

[Bug #21645]

win32-registory can't load fiddle if Gemfile didn't have that dependency.

https://github.com/ruby/resolv/commit/1319183a4b

[hsbt (Hiroshi SHIBATA)]

@Earlopain Thanks for your confirmation. I fixed that at ruby/resolv and ruby/ruby.

[Earlopain (Earlopain _)]

There's a new windows-head build that I tried now. Unfortunately I still get this error. The difference seems to be that bundler-cache: true specifies a vendor directory for bundle install, which I skipped when applying the change. So I fear the patch didn't actually change anything.

If you follow the stacktrace, it never reaches win32/resolv.rb. It fails earlier in something that bundler does. Even if you would catch the error at require of win32/resolv, the required functionality (either powershell or native) would not be there.

Why is it even part of win32-registry in the first place? I don't see that file upstream in https://github.com/ruby/win32-registry, it just lives there in the ruby/ruby copy. If it would be possible to move this file elsewhere so it is not bound by the gemspec, then I think that would solve the problem. Could it be moved to the resolv gem instead? At least the ruby part.

On the other hand, why would specifying a vendor path have any impact here? Perhaps a bundler bug (I would expect it to raise the error with or without the vendor path specified). I cannot tell. To summarize:

name: Test
on: push

jobs:
  make:
    runs-on: windows-latest

    steps:
    - run: echo "source 'https://rubygems.org'" >> Gemfile
    - run: echo "gem 'nokogiri'" >> Gemfile
    - name: Set up Ruby
      uses: ruby/setup-ruby@v1
      with:
        ruby-version: head
    # Commenting out this line makes the error go away
    - run: bundle config --local path D:\a\test\test\vendor\bundle
    - run: bundle install

[Earlopain (Earlopain _)]

@hsbt (Hiroshi SHIBATA) not sure if you got notification for the last message, could you reopen this?

[hsbt (Hiroshi SHIBATA)]

• Status changed from Closed to Assigned

[Earlopain (Earlopain _)]

https://github.com/ruby/resolv/pull/107/commits/b2c775cd80f0ed934336dd1952152982cb3cef14 "improved" this by loading win32/resolv just once and catching the LoadError. CI now passes but as a consequence I guess it will no longer respect nameservers on windows (if there are any)