Bundler fails to resolve native gems with -linux platform suffix on Ruby 4

[asmrtfm]

Summary

On Ruby 4.0.x, bundle install fails to resolve native gems that use the -linux platform suffix (e.g. x86_64-linux, aarch64-linux). Bundler appears to expect -linux-gnu or -linux-musl variants that these gems don't publish.

This affects any native gem using the standard rake-compiler platform names — for example, tailwindcss-ruby < 4.0.

Context

The tailwindcss-ruby maintainer confirmed this is likely a Bundler issue, not something individual gems should work around:

If bundler has -- surprisingly -- stopped supporting -linux platform suffixes then it's mostly likely a bundler bug that we should fix, not something that every gem should be reconfigured to work around.

See: flavorjones/tailwindcss-ruby#126

The rake-compiler-dock docs describe the expected behavior: https://github.com/rake-compiler/rake-compiler-dock#linux-gnu-and-musl

To reproduce

1. Use Ruby 4.0.x
2. gem "tailwindcss-ruby", "< 4.0" in a Gemfile
3. bundle install

Bundler fails to find a gem matching the local platform.

Workaround

Adding explicit -linux-gnu and -linux-musl entries to the gem's NATIVE_PLATFORMS hash resolves the issue, but this shouldn't be necessary per the rake-compiler-dock contract.

Environment

• Ruby: 4.0.5
• Bundler: 2.5.23 / 4.0.10
• Platform: x86_64-linux
• OS: Linux 6.8.0-124-generic

[hsbt]

I could not reproduce this. I tested Ruby 4.0.5 with Bundler 2.5.23, 4.0.10, and master, with the local platform set to both x86_64-linux and x86_64-linux-gnu, covering fresh installs and re-resolution from a lockfile containing -gnu/-musl platforms. Every case resolved and installed tailwindcss-ruby 3.4.19 (x86_64-linux) correctly. A platform gem without a libc suffix is a wildcard that matches both -gnu and -musl, and this behavior is unchanged in RubyGems/Bundler 4.

Please provide the complete output of the failing bundle install, your Gemfile.lock, and bundle env. Without a reproduction, I will close this issue.

/cc @flavorjones

[flavorjones]

@asmrtfm In flavorjones/tailwindcss-ruby#126 I asked for your help to reproduce what you're seeing, as I was also unable to reproduce it. I'm happy to continue the conversation on that issue until we determine the root cause; or we can try to reproduce here. It doesn't make sense to keep both issues open, though.

The best first step you can take is to provide the full output of bundler env which provides a lot of information to help us see what's going on.