@pitrou, thanks for your PR! By analyzing the history of the files in this pull request, we identified @1st1, @serhiy-storchaka and @benjaminp to be potential reviewers.

The test_dis failures are expected, as I haven't updated that file yet.

However, I don't understand the additional test failures under Windows.

Ok, it seems the Windows failures were due to a tracing bug without computed gotos.

Serhiy, do you want to take over this PR? I am not much motivated by the remaining cleanup / dealing with existing cruft.

I take over this PR. Thank you Antoine, you have done hard work for which I did not dare to undertake. I have fetched the branch from your repository.

Thank you Serhiy :-)

It would be quite good to get this change "to the finish line", so to speak. This is an ugly little corner of CPython and cleaning it up is difficult. That's why it has hung around all these years. This patch looks like it does the job, even though it is complicated. It seems to me that 95% of the hard work has been done by Antoine and Mark already.

I have rebased it on the current "master" branch, see nascheme:unwind_stack.

The rebase was not totally painless. I had to re-generate the importlib stuff (not surprising). In ceval, I had to make the following changes:

• use exc_info->exc_* instead of tstate->exc_*
• remove the block under fast_yield that calls restore_and_clear_exc_state() or swap_exc_state()

The unit test test_dist and test_importlib fail for me. It looks like test_dis hasn't been updated to match the latest changes made to the bytecode. Not sure what's wrong with importlib.

Closing this PR as outdated. See PR #4682 and PR #5006 for more recent implementations.