Something happened between 5.3.8.3 and 5.3.8.42 to break

reMatch

. Probably something to do with one of these two: https://luceeserver.atlassian.net/issues/?jql=fixversion%20%20%3E%3D%205.3.8.4%20and%20fixversion%20%3C%3D%205.3.8.42%20and%20text%20~%20regex Repro:

s = ""
pattern = ".*"
writeDump([
    reMatch = s.reMatchNoCase(pattern),
    matches = s.matches(pattern),
    split = s.split(pattern)
])

https://trycf.com/gist/5761040d136d2c4396d89bb60e97043f/lucee5?theme=monokai Compare the difference between Lucee 5 (

reMatch

returns an empty array) and Lucee 4.5 and CF2021 (correctly returns an array with one empty string in it). One might try to reason out of this, saying it's the difference between

this.useJavaAsRegexEngine = true

and

this.useJavaAsRegexEngine = false

. Whilst setting it to

true

does "fix" the issue, that's neither here nor there, because with either Java or PCRE (or... Apache ORO I think, but that's close to a very old version of PRCE I think anyhow?) regexes, the results should be the same:

.*

matches an empty string. Also note changing that setting on CF2021 has no effect: it returns

[""]

either way. Which is correct. This breaks TestBox, for a specific edge-case (which I have raised separately in the testing channel).