[Chapel Merge] Empty regex matching

Branch: refs/heads/main
Revision: bfced52
Author: aconsroe-hpe
Link: Empty regex matching by aconsroe-hpe · Pull Request #18658 · chapel-lang/chapel · GitHub
Log Message:

Merge pull request #18658 from aconsroe-hpe/empty-regex

Empty regex matching

Reviewed by @mppf

This fixes user issue #18639 where an empty regex ie compile("") was infinitely looping on iter matches.

I also found that split behaved in a similar infinite loop and I've fixed it as well.

Paratest passed

Modified Files:
A test/regex/emptyregex.chpl

A test/regex/emptyregex.good
M modules/standard/Regex.chpl
M runtime/src/qio/regex/bundled/re2-interface.cc

Compare: https://github.com/chapel-lang/chapel/compare/8724f3e3221b...bfced523f53f