# File activesupport/lib/active_support/core_ext/regexp.rb, line 11
def multiline?
  options & MULTILINE == MULTILINE
end

Returns true if the regexp has the multiline flag set.

(/./).multiline?  # => false
(/./m).multiline? # => true

Regexp.new(".").multiline?                    # => false
Regexp.new(".", Regexp::MULTILINE).multiline? # => true