This is a blocker, I can't merge this. This is the main reason why IgnoredRegexValidator exists at all.

@ondrejmirtes if I understand the test correctly it was rejecting ...||... regex but the regex is valid, | is an alternation regex token and thus || means alternation with empty string which is fixed by this PR, would you mind amending the test and pushing to by branch directly?

IgnoredRegexValidator makes sure that if people have this in their configuration:

parameters:
	ignoreErrors:
		- '~Result of || is always true.~'

It makes PHPStan fail with the following error:

Invalid entry in ignoreErrors:
Ignored error ~Result of || is always true.~ has an unescaped '||' which leads to ignoring all errors. Use '\|\|' instead.

Sure, but it MUST NOT fail, as it is valid regex :)

So please tell me how to make everyone happy.

It's not a valid regex for ignoreErrors.

Maybe in December, after I release 2.0. Don't expect it sooner.

This is a bugfix into 1.12.x, might I understand why so late?

Because I have different priorities and this is not a severe bug affecting a lot of users.

@ondrejmirtes is now a better time?

About the usecase, see https://github.com/PHP-CS-Fixer/PHP-CS-Fixer/blob/v3.65.0/src/DocBlock/TypeExpression.php#L62 for example.

(a|b|) is shorter syntax of ((?:a|b|)?), the first one is currently now parsed by PHPStan and this PR fixes it.

Hi @ondrejmirtes, please review, the feedback was addressed.