C API: progress variables don't work in format_done

[gaborcsardi]

E.g. format_done = "Completed in {cli::pb_elapsed}".

[jimhester]

Here is a reprex. Sorry for the cpp11 stuff, but it was easier for me to write it like this than trying to remember how to create a named list with the C API functions.

This would need the dev version of cpp11, as there is a bug in the current CRAN release related to the use of cpp11::linking_to.

cpp11::cpp_source(code = '#include <cpp11.hpp>
 #include <cli/progress.h>
[[cpp11::linking_to("cli")]]
[[cpp11::register]]
void pb() {
  int i;
  using namespace cpp11::literals;
  cpp11::writable::list config({"clear"_nm = false, "format_done"_nm = "Completed in {cli::pb_elapsed}."});
  SEXP bar = PROTECT(cli_progress_bar(1000, config));
  for (i = 0; i < 1000; i++) {
    cli_progress_sleep(0, 4 * 1000 * 1000);
    if (CLI_SHOULD_TICK) cli_progress_set(bar, i);
  }
  cli_progress_done(bar);
  UNPROTECT(1);
}')

pb()