class RSpec::Expectations::LegacyMatcherAdapter

def initialize(matcher)
  super
  ::RSpec.warn_deprecation(<<-EOS.gsub(/^\s+\|/, ''), :type => "legacy_matcher")
    |#{matcher.class.name || matcher.inspect} implements a legacy RSpec matcher
    |protocol. For the current protocol you should expose the failure messages
    |via the `failure_message` and `failure_message_when_negated` methods.
    |(Used from #{CallerFilter.first_non_rspec_line})
  EOS
end