module RuboCop::Cop::DocumentationComment

or a Parser::Source::Comment. Both respond to #loc.
The args node1 & node2 may represent a RuboCop::AST::Node

def preceding_comment?(node1, node2)
  node1 && node2 && precede?(node2, node1) &&
    comment_line?(node2.loc.expression.source)
end

Modules