On the contrary, build2 is a language-agnostic, general-purpose build system. There is the bash module[1], for example. And now that we have support for dynamically buildable/loadable build system modules, we can develop support for more languages, code generators, etc., without bundling it with the build system core. I myself am itching to take a stab at Rust. Hopefully will find time after the release.

[1] https://build2.org/build2/doc/build2-build-system-manual.xht...