It wouldn’t be so bad if it weren’t that it’s a hanging failure — one that requires force closing Notepad++ and hence losing all unsaved work. I made a bad error, and I didn’t discover it in time to fix it for two entire releases. I can only apologize for that, and leave it to others to decide how to minimize the damage.

No problem @Coises
It was me who merged this PR so I take the whole responsibility of the regression.

The argument is taken. The v8.7.9 will be retained and v8.8 will be release ASAP.

Fortunately, it does not hang for find-all nor replace-all. For example, a common search/replace is to search for ^ or $ to insert something at the start or end of each line. Those are not hanging which is likely why the issue did not get noticed until recently.

If I search for ^ or $ though and start tapping F3 to inspect the start or end of each line then npp will hang instead of wrapping from the end of a file to the beginning. ^ only hangs if the last line is blank.

I hung npp by accident today as I wanted to mark the first 20 characters of each line and used ^{0,20} rather than ^{1,20}. Fortunately, Notepad++'s background file backup continues to work when it’s hung meaning pretty much all someone is likely to loose is their recent search/replace history and other recent changes to the settings that are stored in config.xml.

regexp hanging can only be reproduced under specific conditions. Notably, the issue has existed for a long time and it’s not truly a regression - it’s more accurately a shifted bug caused by a previous fix.

Not an objection, exactly, but a note, as the person who authored the flawed fix in 8.7.8 and the pending fix to the fix (that I didn’t discover in time to get it into 8.7.9):

The pre-8.7.8 failure case is indeed very specific; there has to be a null match in a UTF-8 file just before non-ASCII character, then the next attempt to match has to match one component of the expression and then attempt to backtrack to the starting position (which will be incorrectly determined, causing the bug).

The 8.7.8/8.7.9 failure case happens whenever there is a null match at the end of the file. Doesn’t have to be UTF-8, doesn’t have to involve a non-ASCII character. So, realistically, I think the new failure case will be more common than the original one. Maybe much more common.

Whether it will be common enough that promoting a release without the fix to the fix is a bad idea isn’t something I know how to judge… and it certainly isn’t my call.

It wouldn’t be so bad if it weren’t that it’s a hanging failure — one that requires force closing Notepad++ and hence losing all unsaved work. I made a bad error, and I didn’t discover it in time to fix it for two entire releases. I can only apologize for that, and leave it to others to decide how to minimize the damage.

1. Both regressions will not impact most users:

• Few users utilize vertical tabbar.
• regexp hanging can only be reproduced under specific conditions. Notably, the issue has existed for a long time and it’s not truly a regression - it’s more accurately a shifted bug caused by a previous fix.

2. Currently auto-update is triggered for v8.7.5, which contains a critical regression saving backup file without modifications. This issue has been resolved in v8.7.8.
3. Triggering auto-update for v8.7.9 means a larger user base will adopt the version, allowing us to identify any critical issues more quickly and avoid chasing regressions in the next release.

So, if there is no objections, auto-update will be initiated for v8.7.9, in about 12 hours.
Please let me know your thought.

@donho, would you prefer that I prepare another pull request (after further testing)? Submit an issue and a pull request? Leave this to you?

Pull request #16371 submitted. Let me know if I should do anything else.

Changing the line that changed:

return _document->NextPosition(position, 1);

to

return std::max(_document->NextPosition(position, 1), position + 1);

appears to fix it.

@donho, would you prefer that I prepare another pull request (after further testing)? Submit an issue and a pull request? Leave this to you?

Open a new tab and type two lines:

abc
def

Open the Find dialog; turn off wrap around, set regular expression, and enter:
.*
as the find expression. Place the caret at the beginning of the file, then click Find repeatedly. First it finds abc; then a zero length match; then def; then a zero length match.

In 8.7.7, clicking Find a fifth time produces the error message Can’t find the text “.*” from caret to end-of-file. In 8.7.8 and 8.7.9, Notepad++ becomes unresponsive.

Other tests suggest the problem occurs whenever there is a zero length match at the end of the file.