[hsbt]

ubuntu-latest is moving to ubuntu-26.04 (actions/runner-images#14748), and setup-ruby has no builds of Ruby 3.1 and older there, so CI jobs across the ecosystem that test those versions on ubuntu-latest fail at setup. ruby/actions#156 found 87 repositories in the ruby org alone, and I've been moving such jobs to ubuntu-24.04 (tdiary/tdiary-core#1418, tdiary/tdiary-contrib#262, tdiary/tdiary-style-gfm#39).

They fail to build there because GCC 15 defaults to C23 and GCC 14 made implicit declarations errors. The first commit passes the minimal flags on CC for those versions, and the second adds them to the matrix for ubuntu-26.04 and ubuntu-26.04-arm. I built 1.9.3 through 3.1.7 with ruby-build in an ubuntu:26.04 container, including the https and gem install json checks. I haven't tried arm64.

It would be great if you could merge this and publish the binaries. Thanks for maintaining ruby-builder and setup-ruby.

Generated with Claude Code

setup-ruby issue: ruby/setup-ruby#954

[eregon]

Thank you for the PR.
Is the workaround something we could do in https://github.com/rbenv/ruby-build instead?
I think so, because there is a similar workaround but it's currently Fedora-only: https://github.com/rbenv/ruby-build/blob/b6a92c15f0df872047c74f7dfa0b92dfd4de8a92/bin/ruby-build#L743-L755
I think that would be the more-generally-useful fix, and a better place for this logic.

In general I'm not very keen to adding workarounds here, but no objection if ruby-build fixes such issues as then there is no need for a workaround here.

The second commit looks great, happy to merge that once ruby-build handles the C23/C17 issue.

[eregon]

I'm making a PR to ruby-build to handle this.
My plan is to only handle Ruby 2.3+, I'm unsure we should add workarounds for 2.0-2.2 and 1.9, nobody should use those anymore and I think it's fully expected they don't build on recent platforms.

[eregon]

rbenv/ruby-build#2649 and I've cherry-picked your second commit as d86a862

[eregon]

2.4 - 3.1 are built, except 2.7 which failed unexpectedly, investigating:
https://github.com/ruby/ruby-builder/actions/runs/41236443425/job/124641118792

2.3 fails like 2.2 and older with undefined references in openssl (libcrypto.so), which reinforces my thinking we should not bother with it.

[eregon]

Fix for 2.7: rbenv/ruby-build#2650
And builds running in https://github.com/ruby/ruby-builder/actions/runs/41238488842/job/124647171402

[eregon]

I'll close this as I have integrated the changes, thank you for the help!

[hsbt]

👍 Thanks for porting it to ruby-build and getting 2.4 to 3.1 out so quickly.