Function rustc_codegen_ssa::back::linker::get_linker

pub fn get_linker<'a>(
    sess: &'a Session,
    linker: &Path,
    flavor: LinkerFlavor,
    self_contained: bool,
    target_cpu: &'a str
) -> Box<dyn Linker + 'a>

The third parameter is for env vars, used on windows to set up the path for MSVC to find its DLLs, and gcc to find its bundled toolchain