How can I 'tell' regression builders to skip building GIL

where required C++ version is not supported? Add requirements to you tests Jamfile, something like: import config : requires ; project /boost/gil/test : requirements [ requires cxx11_constexpr cxx11_decltype cxx11_template_aliases cxx11_variadic_templates ] (those checks come from Config library which most likely you are pulling already in your CI builds). I noticed that some libraris specify "std" in libraries.json, for example:

- Any: "std": [ "c++17" ] - Ratio: "std": [ "proposal" ] What is the purpose of these? Is this respected by regression builds?

I doubt those do anything. IIUC `libraries.json` is used only for https://www.boost.org/doc/libs/ list generation.