Issue #19143 has been updated by nobu (Nobuyoshi Nakada). It is intended. `*.so` files are architecture-dependent, which are "tainted" in other words, while `lib` directories are architecture-independent, "untainted". "Tainted" files should not infect "untainted" directories. ---------------------------------------- Bug #19143: Windows - bundled extension gems compile, but don't copy *.so files to lib folder https://bugs.ruby-lang.org/issues/19143#change-100378 * Author: MSP-Greg (Greg L) * Status: Closed * Priority: Normal * Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN ---------------------------------------- Just finished updating ruby-loco's mswin build to use a system similar to the ucrt & mingw builds. Confirmed something I noticed previously, and also occurs with the RubyInstaller2 head build. On Windows, bundled extension gems (debug, rbs) compile their extension in the `ext` folder, but do not copy them to the `lib` folder. So, the *.so file is created, but not copied. I think this was working correctly on Ruby 3.1? -- https://bugs.ruby-lang.org/