# frozen_string_literal: true module RuboCop module Cop module Style # Checks for redundant argument forwarding when calling super with arguments identical to # the method definition. # # Using zero arity `super` within a `define_method` block results in `RuntimeError`: # # [source,ruby] # ---- # def m # define_method(:foo) { super() } # => OK # end # # def m # define_method(:foo) { super } # => RuntimeError # end # ---- # # Furthermore, any arguments accompanied by a block may potentially be delegating to # `define_method`, therefore, `super` used within these blocks will be allowed. # This approach might result in false negatives, yet ensuring safe detection takes precedence. # # NOTE: When forwarding the same arguments but replacing the block argument with a new inline # block, it is not necessary to explicitly list the non-block arguments. As such, an offense # will be registered in this case. # # @example # # bad # def method(*args, **kwargs) # super(*args, **kwargs) # end # # # good - implicitly passing all arguments # def method(*args, **kwargs) # super # end # # # good - forwarding a subset of the arguments # def method(*args, **kwargs) # super(*args) # end # # # good - forwarding no arguments # def method(*args, **kwargs) # super() # end # # # bad - forwarding with overridden block # def method(*args, **kwargs, &block) # super(*args, **kwargs) { do_something } # end # # # good - implicitly passing all non-block arguments # def method(*args, **kwargs, &block) # super { do_something } # end # # # good - assigning to the block variable before calling super # def method(&block) # # Assigning to the block variable would pass the old value to super, # # under this circumstance the block must be referenced explicitly. # block ||= proc { 'fallback behavior' } # super(&block) # end class SuperArguments < Base extend AutoCorrector DEF_TYPES = %i[def defs].freeze ASSIGN_TYPES = %i[or_asgn lvasgn].freeze MSG = 'Call `super` without arguments and parentheses when the signature is identical.' MSG_INLINE_BLOCK = 'Call `super` without arguments and parentheses when all positional ' \ 'and keyword arguments are forwarded.' def on_super(super_node) return unless (def_node = find_def_node(super_node)) def_node_args = def_node.arguments.argument_list super_args = preprocess_super_args(super_node.arguments) return unless arguments_identical?(def_node, super_node, def_node_args, super_args) # If the number of arguments to the def node and super node are different here, # it's because the block argument is not forwarded. message = def_node_args.size == super_args.size ? MSG : MSG_INLINE_BLOCK add_offense(super_node, message: message) do |corrector| corrector.replace(super_node, 'super') end end private def find_def_node(super_node) super_node.ancestors.find do |node| # When defining dynamic methods, implicitly calling `super` is not possible. # Since there is a possibility of delegation to `define_method`, # `super` used within the block is always allowed. break if node.block_type? && !block_sends_to_super?(super_node, node) break node if DEF_TYPES.include?(node.type) end end # rubocop:disable Metrics/CyclomaticComplexity, Metrics/PerceivedComplexity def arguments_identical?(def_node, super_node, def_args, super_args) return false if argument_list_size_differs?(def_args, super_args, super_node) def_args.zip(super_args).each do |def_arg, super_arg| next if positional_arg_same?(def_arg, super_arg) next if positional_rest_arg_same(def_arg, super_arg) next if keyword_arg_same?(def_arg, super_arg) next if keyword_rest_arg_same?(def_arg, super_arg) next if block_arg_same?(def_node, super_node, def_arg, super_arg) next if forward_arg_same?(def_arg, super_arg) return false end true end # rubocop:enable Metrics/CyclomaticComplexity, Metrics/PerceivedComplexity def argument_list_size_differs?(def_args, super_args, super_node) # If the def node has a block argument and the super node has an explicit block, # the number of arguments is the same, so ignore the def node block arg. def_args_size = def_args.size def_args_size -= 1 if def_args.any?(&:blockarg_type?) && block_sends_to_super?(super_node) def_args_size != super_args.size end def block_sends_to_super?(super_node, parent_node = super_node.parent) # Checks if the send node of a block is the given super node, # or a method chain containing it. return false unless parent_node return false unless parent_node.type?(:block, :numblock) parent_node.send_node.each_node(:super).any?(super_node) end def positional_arg_same?(def_arg, super_arg) return false unless def_arg.arg_type? || def_arg.optarg_type? return false unless super_arg.lvar_type? def_arg.name == super_arg.children.first end def positional_rest_arg_same(def_arg, super_arg) return false unless def_arg.restarg_type? # anonymous forwarding return true if def_arg.name.nil? && super_arg.forwarded_restarg_type? return false unless super_arg.splat_type? return false unless (lvar_node = super_arg.children.first).lvar_type? def_arg.name == lvar_node.children.first end def keyword_arg_same?(def_arg, super_arg) return false unless def_arg.kwarg_type? || def_arg.kwoptarg_type? return false unless (pair_node = super_arg).pair_type? return false unless (sym_node = pair_node.key).sym_type? return false unless (lvar_node = pair_node.value).lvar_type? return false unless sym_node.source == lvar_node.source def_arg.name == sym_node.value end def keyword_rest_arg_same?(def_arg, super_arg) return false unless def_arg.kwrestarg_type? # anonymous forwarding return true if def_arg.name.nil? && super_arg.forwarded_kwrestarg_type? return false unless super_arg.kwsplat_type? return false unless (lvar_node = super_arg.children.first).lvar_type? def_arg.name == lvar_node.children.first end def block_arg_same?(def_node, super_node, def_arg, super_arg) return false unless def_arg.blockarg_type? return true if block_sends_to_super?(super_node) return false unless super_arg.block_pass_type? # anonymous forwarding return true if (block_pass_child = super_arg.children.first).nil? && def_arg.name.nil? block_arg_name = block_pass_child.children.first def_arg.name == block_arg_name && !block_reassigned?(def_node, block_arg_name) end # Reassigning the block argument will still pass along the original block to super # https://bugs.ruby-lang.org/issues/20505 def block_reassigned?(def_node, block_arg_name) def_node.each_node(*ASSIGN_TYPES).any? do |assign_node| # TODO: Since `Symbol#name` is supported from Ruby 3.0, the inheritance check for # `AST::Node` can be removed when requiring Ruby 3.0+. lhs = assign_node.node_parts[0] next if lhs.is_a?(AST::Node) && !lhs.respond_to?(:name) assign_node.name == block_arg_name end end def forward_arg_same?(def_arg, super_arg) def_arg.forward_arg_type? && super_arg.forwarded_args_type? end def preprocess_super_args(super_args) super_args.flat_map do |node| if node.hash_type? && !node.braces? node.children else node end end end end end end end