Hermetic Builds. ... Our builds are hermetic, meaning that they are insensitive to the libraries and other software installed on the build machine. Instead, builds depend on known versions of build tools, such as compilers, and dependencies, such as libraries.
Kind of like a container for building? I had to look it up myself.
That, and also insensitive to builds you might have done of other versions of the source code, etc. I.e. it's not affected by "files left behind" that would require you to do a clean build and lose incrementality.
I don't know if this is what the parent was intending (I'm curious to see other examples), but depending on your definition Nix (nixos.org) seems to fit that need.
Kind of like a container for building? I had to look it up myself.