Issue #21286 has been updated by hsbt (Hiroshi SHIBATA). I added `gcc-15` to our CI: https://github.com/ruby/ruby/actions/runs/14746546198/job/41394898928#step:7... It's working fine with Ubuntu-25.04. This issue only happened with MSYS2 or Windows environment. ---------------------------------------- Bug #21286: Windows - MSYS2 just updated to GCC 15.1.0, builds failing https://bugs.ruby-lang.org/issues/21286#change-112834 * Author: MSP-Greg (Greg L) * Status: Open * ruby -v: master * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- MSYS2 just updated to GCC 15.1.0, and the ruby-loco builds failed to compile. See [MinGW](https://github.com/MSP-Greg/ruby-loco/actions/runs/14693708990/job/412325097...) & [UCRT](https://github.com/MSP-Greg/ruby-loco/actions/runs/14693775816/job/412326620...) Also, I compiled mswin locally with the recent VS 'preview' release, and the bug has been fixed. -- https://bugs.ruby-lang.org/