Class: RuboCop::Cop::Style::RedundantSelfAssignment

Inherits:
Base
  • Object
show all
Extended by:
AutoCorrector
Includes:
RangeHelp
Defined in:
lib/rubocop/cop/style/redundant_self_assignment.rb

Overview

This cop checks for places where redundant assignments are made for in place modification methods.

This cop is marked as unsafe, because it can produce false positives for user defined methods having one of the expected names, but not modifying its receiver in place.

Examples:

# bad
args = args.concat(ary)
hash = hash.merge!(other)

# good
args.concat(foo)
args += foo
hash.merge!(other)

# bad
self.foo = foo.concat(ary)

# good
foo.concat(ary)
self.foo += ary

Constant Summary collapse

MSG =
'Redundant self assignment detected. '\
'Method `%<method_name>s` modifies its receiver in place.'
METHODS_RETURNING_SELF =
%i[
  append clear collect! compare_by_identity concat delete_if
  fill initialize_copy insert keep_if map! merge! prepend push
  rehash replace reverse! rotate! shuffle! sort! sort_by!
  transform_keys! transform_values! unshift update
].to_set.freeze
ASSIGNMENT_TYPE_TO_RECEIVER_TYPE =
{
  lvasgn: :lvar,
  ivasgn: :ivar,
  cvasgn: :cvar,
  gvasgn: :gvar
}.freeze

Constants inherited from Base

Base::RESTRICT_ON_SEND

Instance Attribute Summary

Attributes inherited from Base

#config, #processed_source

Instance Method Summary collapse

Methods included from AutoCorrector

support_autocorrect?

Methods inherited from Base

#add_global_offense, #add_offense, autocorrect_incompatible_with, badge, #callbacks_needed, callbacks_needed, #config_to_allow_offenses, #config_to_allow_offenses=, #cop_config, #cop_name, cop_name, department, documentation_url, exclude_from_registry, #excluded_file?, #external_dependency_checksum, inherited, #initialize, joining_forces, lint?, match?, #message, #offenses, #on_investigation_end, #on_new_investigation, #on_other_file, #parse, #ready, #relevant_file?, support_autocorrect?, support_multiple_source?, #target_rails_version, #target_ruby_version

Methods included from ExcludeLimit

#exclude_limit

Methods included from AutocorrectLogic

#autocorrect?, #autocorrect_enabled?, #autocorrect_requested?, #correctable?, #disable_uncorrectable?, #safe_autocorrect?

Methods included from IgnoredNode

#ignore_node, #ignored_node?, #part_of_ignored_node?

Methods included from Util

silence_warnings

Constructor Details

This class inherits a constructor from RuboCop::Cop::Base

Instance Method Details

#on_lvasgn(node) ⇒ Object Also known as: on_ivasgn, on_cvasgn, on_gvasgn


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# File 'lib/rubocop/cop/style/redundant_self_assignment.rb', line 51

def on_lvasgn(node)
  lhs, rhs = *node
  receiver, method_name, = *rhs
  return unless receiver && method_returning_self?(method_name)

  receiver_type = ASSIGNMENT_TYPE_TO_RECEIVER_TYPE[node.type]
  return unless receiver.type == receiver_type && receiver.children.first == lhs

  message = format(MSG, method_name: method_name)
  add_offense(node.loc.operator, message: message) do |corrector|
    corrector.replace(node, rhs.source)
  end
end

#on_send(node) ⇒ Object


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# File 'lib/rubocop/cop/style/redundant_self_assignment.rb', line 68

def on_send(node)
  # TODO: Remove `Symbol#to_s` after supporting only Ruby >= 2.7.
  return unless node.method_name.to_s.end_with?('=')
  return unless redundant_assignment?(node)

  message = format(MSG, method_name: node.first_argument.method_name)
  add_offense(node.loc.operator, message: message) do |corrector|
    corrector.remove(correction_range(node))
  end
end