LibRegex: Incorrect matches when using variable-width lookbehinds

[aplefull]

Summary

When using lookbehind assertions with quantifiers (.*), match() produces incorrect results. I lost the original source for the reduction, unfortunately

Operating system

Linux

Steps to reproduce

N/A

Expected behavior

Provided in reduced test case

Actual behavior

Provided in reduced test case

URL for a reduced test case

N/A

HTML/SVG/etc. source for a reduced test case

<script>
  const match1 = "a b".match(/(?<=a.*)b/g); // Expected: ["b"], Actual: null
  const match2 = "a b".match(/(?<=a.*).*?/g); // Expected: ["", "", ""], Actual: [""]
  const match3 = "a b".match(/(?<!a.*)(?<=b).*/g); // Expected: null, Actual: [""]

  console.log(match1, match2, match3);
</script>

Log output and (if possible) backtrace

N/A

Screenshots or screen recordings

No response

Build flags or config settings

No response

Contribute a patch?

• I’ll contribute a patch for this myself.

[AtkinsSJ]

Pinging @alimpfard

[alimpfard]

Ah this nonsense. Yeah this one I am very aware of, I was hoping we'd never see it in the wild :(