I broadly agree that the warning is very annoying, particularly when it comes from third-party packages (I see it from some of pip's vendored dependencies all the time),
The same here as well. The other annoyance is that it pops up during live demos, student teaching sessions, and during ipython data analysis in a way that becomes a distractor and makes Python look and feel like it is broken. I haven't found a since case where it improved the user experience.
though I do also see many people bitten by FileNotFoundError because of a '\n' in their filename.
Yes, I've seen that as well. Unfortunately, the syntax warning or error doesn't detect that case. It only complains about invalid sequences which weren't the actual problem we were trying to solve. The new warning soon-to-be error breaks code that currently works but is otherwise innocuous.
Raymond - a question if I may. How often do you see these occurring from docstrings, compared to regular strings?
About half. Thanks for weighing in. I think this is an important usability discussion. IMO it is the number one issue affecting the end user experience with this release. If we could get more people to actively use the beta release, the issue would stand-out front and center. But if people don't use the beta in earnest, we won't have confirmation until it is too late. We really don't have to go this path. Arguably, the implicit conversion of '\latex' to '\\latex' is a feature that has existed for three decades, and now we're deciding to turn it off to define existing practices as errors. I don't think any commercial product manager would allow this to occur without a lot of end user testing. Raymond P.S. In the world of C compilers, I suspect that if the relatively new compiler warnings were treated as errors, the breakage would be widespread. Presumably that's why they haven't gone down this road.