A regex after an operator, like so:
foo + /bar/
foo - /bar/
foo << /bar/
foo << /bar\/baz/
does not get highlighted at all:
Using the latest vim-ruby head (423286e).
Highlight regexps after <<, +, -, and *
This has always been a tightrope walk with false positives on division. I broadened the regex regex a bit.