Function compile_project 

pub fn compile_project(
    root: &str,
    loader: &dyn Loader,
    lock: Option<&Lock>,
    map: &mut SourceMap,
    diags: &mut Diagnostics,
) -> Option<Placed>

Compile a whole project: check, link, and slice.

The caller’s SourceMap is what every module is added to, because a diagnostic about the third module in a project has to be renderable by whoever asked for the first.