Gem::Ext::CargoBuilder#build

# File tmp/rubies/ruby-3.4.1/lib/rubygems/ext/cargo_builder.rb, line 19
def build(extension, dest_path, results, args = [], lib_dir = nil, cargo_dir = Dir.pwd,
  target_rbconfig=Gem.target_rbconfig)
  require "tempfile"
  require "fileutils"

  if target_rbconfig.path
    warn "--target-rbconfig is not yet supported for Rust extensions. Ignoring"
  end

  # Where's the Cargo.toml of the crate we're building
  cargo_toml = File.join(cargo_dir, "Cargo.toml")
  # What's the crate's name
  crate_name = cargo_crate_name(cargo_dir, cargo_toml, results)

  begin
    # Create a tmp dir to do the build in
    tmp_dest = Dir.mktmpdir(".gem.", cargo_dir)

    # Run the build
    cmd = cargo_command(cargo_toml, tmp_dest, args, crate_name)
    runner.call(cmd, results, "cargo", cargo_dir, build_env)

    # Where do we expect Cargo to write the compiled library
    dylib_path = cargo_dylib_path(tmp_dest, crate_name)

    # Helpful error if we didn't find the compiled library
    raise DylibNotFoundError, tmp_dest unless File.exist?(dylib_path)

    # Cargo and Ruby differ on how the library should be named, rename from
    # what Cargo outputs to what Ruby expects
    dlext_name = "#{crate_name}.#{makefile_config("DLEXT")}"
    dlext_path = File.join(File.dirname(dylib_path), dlext_name)
    FileUtils.cp(dylib_path, dlext_path)

    nesting = extension_nesting(extension)

    if Gem.install_extension_in_lib && lib_dir
      nested_lib_dir = File.join(lib_dir, nesting)
      FileUtils.mkdir_p nested_lib_dir
      FileUtils.cp_r dlext_path, nested_lib_dir, remove_destination: true
    end

    # move to final destination
    nested_dest_path = File.join(dest_path, nesting)
    FileUtils.mkdir_p nested_dest_path
    FileUtils.cp_r dlext_path, nested_dest_path, remove_destination: true
  ensure
    # clean up intermediary build artifacts
    FileUtils.rm_rf tmp_dest if tmp_dest
  end

  results
end