[simonask]

I think "build systems" is a too broad category in that argument.

Language-specific build facilities, like Cargo's build.rs and Zig's build scripts, typically have a limited scope - generating a bit of source code, discovering some linker flags, stuff like that. These scripts need to be run by LSP servers when opening the project in an editor to get basic features working, so that's a fairly risky thing.

They are also currently doing things like invoking CMake and other build systems, but you could definitely conceive of a world where that was a separate step in the build process, and that world seems pretty attractive to me.

A common pattern in Rust projects is to have a `*-sys` crate representing the C FFI bindings, and they typically also do something like invoke CMake or similar to actually build the C/C++ library underneath. But if you have a larger project that already integrates multiple build systems, this is really quite inconvenient in most cases.

[Panzerschrek]

Your proposal still contains a security hole, since it still allows executing cmake or something similar. Adding sandboxing in some parts/steps of a build system has no benefits, as soon as the system as whole has loopholes allowing bypassing such sandboxing. It's like adding more locks to the front door, when the backdoor has no locks at all.

[simonask]

Security is not, and in fact can never be, all-or-nothing. An imperfect solution is better than no solution. Developers have the reasonable expectation that opening a project in VS Code does not upload their home directory to a remote server. Performing a full build of a project is a different operation with different associated expectations.