It's used to do all sorts of things. Rust version probing, bindings generation, precompiling bundled data, etc. The only reason it isn't used to do more is beca

It's used to do all sorts of things. Rust version probing, bindings generation, precompiling bundled data, etc. The only reason it isn't used to do more is because proc macros do it instead, with an essentially identical execution model and sandboxing situation (ie build scripts in isolation are a red herring).