class RuboCop::Cop::Performance::MapMethodChain


array.map { |item| item.foo.bar }
# good
array.map(&:foo).map(&:bar)
# bad
@example
—-
[X.new, X.new].map { |x| x.foo.bar } # => [2, 4]
[X.new, X.new].map(&:foo).map(&:bar) # => [4, 4]
end
end
@@num * 2
def bar
end
self
@@num += 1
def foo
end
@@num = 0
def initialize
class X
—-
[source,ruby]

affects the return value of subsequent methods.
This cop is unsafe because false positives occur if the number of times the first method is executed
@safety
Autocorrection is not supported because an appropriate block variable name cannot be determined automatically.
Checks if the map method is used in a chain.

def find_begin_of_chained_map_method(node, map_args)

rubocop:disable Metrics/CyclomaticComplexity 
def find_begin_of_chained_map_method(node, map_args)
  return unless (chained_map_method = node.receiver)
  return if !chained_map_method.call_type? || !RESTRICT_ON_SEND.include?(chained_map_method.method_name)
  return unless (map_arg = block_pass_with_symbol_arg?(chained_map_method.first_argument))
  map_args.unshift(map_arg)
  receiver = chained_map_method.receiver
  return chained_map_method unless receiver&.call_type? && block_pass_with_symbol_arg?(receiver.first_argument)
  find_begin_of_chained_map_method(chained_map_method, map_args)
end

def on_send(node) 

def on_send(node)
  return if part_of_ignored_node?(node)
  return unless (map_arg = block_pass_with_symbol_arg?(node.first_argument))
  map_args = [map_arg]
  return unless (begin_of_chained_map_method = find_begin_of_chained_map_method(node, map_args))
  range = begin_of_chained_map_method.loc.selector.begin.join(node.source_range.end)
  message = format(MSG, method_name: begin_of_chained_map_method.method_name, map_args: map_args.join('.'))
  add_offense(range, message: message)
  ignore_node(node)
end