[ruby-core:116395] [Ruby master Bug#20207] Segmentation fault for a regexp containing positive and negative lookaheads

["Sundeep (Sundeep Agarwal) via ruby-core" <ruby-core@ml.ruby-lang.org>]

Issue #20207 has been reported by Sundeep (Sundeep Agarwal).

----------------------------------------
Bug #20207: Segmentation fault for a regexp containing positive and negative lookaheads
https://bugs.ruby-lang.org/issues/20207

* Author: Sundeep (Sundeep Agarwal)
* Status: Open
* Priority: Normal
* Backport: 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN
----------------------------------------
I'm getting segmentation fault for the following regexp with Ruby 3.3.0:

``` ruby
puts 'clan'.match?(/(?=.*a)(?!.*n)/)
```

This is the minimal example for which I was able to produce the issue. `a` and `n` in the above example
are just a sample, can be other character combinations too. There has to be at least two characters
before them in the input string (`cl` in the above example).

The error is seen when the above code is run from a file, but only occasionally from irb.
When run from a file, most of the time I get segmentation fault (see attached log file),
but sometimes I get the following error:

``` ruby
lookaround.rb:1:in `match?': undefined bytecode (bug): /(?=.*a)(?!.*n)/ (RegexpError)
	from lookaround.rb:1:in `<main>'
```

When asked in the r/ruby forum, somebody else was able to reproduce this issue.
They also mentioned that the issue wasn't seen in the Ruby 3.2.2 version.

---Files--------------------------------
lookaround_segfault.log (15.9 KB)


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