We merged string processing in May 2020 (#1132), almost four years ago. A few months later, I put the feature behind a flag because there were too many related bugs (#1609). Four years later, we're still in basically the same state: most of the open issues in C: preview style Issues with the preview and unstable style. Add the name of the responsible feature in the title. are about string processing.

I'm also increasingly convinced that string_processing's core feature, splitting up long strings, would be exceedingly controversial if we ever did turn it on by default. It is just too hard for a tool to figure out how to split a string in a way that makes sense to readers of the code. However, there are other things that string_processing does, and some of those are valuable and could perhaps be split off.

So my proposal is:

• Give up on splitting strings automatically; Black will simply not do that
• Split out any other useful features from string-processing into separate preview features that we can reasonably hope to enable in next year's stable style.

If you're interested in getting any part of string_processing into stable Black, please contribute a PR moving it to a separate preview feature.

I ran string_processing on my work codebase and noticed a few specific changes that could be split out. I'll list them in a separate comment.