⚠️ GitHub issue #39864 has been automatically assigned in GitHub to PR creator.

MapType::ToString() don't show the metadata currently. It use type().ToString() and field.name().

I didn't change here.

  const auto print_field_name = [](std::ostream& os, const Field& field,
                                   const char* std_name) {
    if (field.name() != std_name) {
      os << " ('" << field.name() << "')";
    }
  };
  const auto print_field = [&](std::ostream& os, const Field& field,
                               const char* std_name) {
    os << field.type()->ToString(show_metadata);
    print_field_name(os, field, std_name);
  };

Can you also change AssertTypeEqual so that it shows the metadata on error?

AssertTypeEqual(ty1, ty2, /*check_metadata*/true);
Should I do it above way or modify the implementation of AssertTypeEqual?

I mean change these now that DataType::ToString accepts a show_metadata argument:

I mean change these now that DataType::ToString accepts a show_metadata argument:

Thank you! I see.

After merging your PR, Conbench analyzed the 7 benchmarking runs that have been run so far on merge-commit c5f60a0.

There were no benchmark performance regressions. 🎉

The full Conbench report has more details. It also includes information about 12 possible false positives for unstable benchmarks that are known to sometimes produce them.

I've made a few minor changes. Thanks @Cerdore for tackling this, I'll be merging this PR if CI passes.

Sorry, I've been busy with some other things lately... And thank you very much for your suggestions and subsequent changes!