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Class: RuboCop::Cop::Lint::ShadowingOuterLocalVariable

Relationships & Source Files
Super Chains via Extension / Inclusion / Inheritance
Class Chain:
self, ::RuboCop::Cop::Base, ::RuboCop::ExcludeLimit, NodePattern::Macros, RuboCop::AST::Sexp
Instance Chain:
Inherits: RuboCop::Cop::Base
Defined in: lib/rubocop/cop/lint/shadowing_outer_local_variable.rb

Overview

Checks for the use of local variable names from an outer scope in block arguments or block-local variables. This mirrors the warning given by ruby -cw prior to Ruby 2.6: "shadowing outer local variable - foo".

Note
Shadowing of variables in block passed to Ractor.new is allowed because Ractor should not access outer variables. eg. following style is encouraged:
worker_id, pipe = env
Ractor.new(worker_id, pipe) do |worker_id, pipe|
end

Examples:

# bad
def some_method
  foo = 1

  2.times do |foo| # shadowing outer `foo`
    do_something(foo)
  end
end

# good
def some_method
  foo = 1

  2.times do |bar|
    do_something(bar)
  end
end

Constant Summary

::RuboCop::Cop::Base - Inherited

EMPTY_OFFENSES, RESTRICT_ON_SEND

Class Attribute Summary

::RuboCop::Cop::Base - Inherited

.gem_requirements, .lint?,
.support_autocorrect?

Returns if class supports autocorrect.

.support_multiple_source?

Override if your cop should be called repeatedly for multiple investigations Between calls to on_new_investigation and on_investigation_end, the result of processed_source will remain constant.

Class Method Summary

::RuboCop::Cop::Base - Inherited

.autocorrect_incompatible_with

List of cops that should not try to autocorrect at the same time as this cop.

.badge

Naming.

.callbacks_needed, .cop_name, .department,
.documentation_url

Returns an url to view this cops documentation online.

.exclude_from_registry

Call for abstract Cop classes.

.inherited,
.joining_forces

Override and return the Force class(es) you need to join.

.match?

Returns true if the cop name or the cop namespace matches any of the given names.

.new,
.requires_gem

Register a version requirement for the given gem name.

.restrict_on_send

::RuboCop::ExcludeLimit - Extended

exclude_limit

Sets up a configuration option to have an exclude limit tracked.

transform

Instance Attribute Summary

Instance Method Summary

::RuboCop::Cop::Base - Inherited

#add_global_offense

Adds an offense that has no particular location.

#add_offense

Adds an offense on the specified range (or node with an expression) Unless that offense is disabled for this range, a corrector will be yielded to provide the cop the opportunity to autocorrect the offense.

#begin_investigation

Called before any investigation.

#callbacks_needed,
#cop_config

Configuration Helpers.

#cop_name, #excluded_file?,
#external_dependency_checksum

This method should be overridden when a cop’s behavior depends on state that lives outside of these locations:

#inspect,
#message

Gets called if no message is specified when calling add_offense or add_global_offense Cops are discouraged to override this; instead pass your message directly.

#name

Alias for Base#cop_name.

#offenses,
#on_investigation_end

Called after all on_…​

#on_new_investigation

Called before all on_…​

#on_other_file

Called instead of all on_…​

#parse

There should be very limited reasons for a Cop to do it’s own parsing.

#parser_engine,
#ready

Called between investigations.

#relevant_file?, #target_rails_version, #target_ruby_version, #annotate, #apply_correction, #attempt_correction,
#callback_argument

Reserved for Cop::Cop.

#complete_investigation

Called to complete an investigation.

#correct, #current_corrector,
#current_offense_locations

Reserved for Commissioner:

#current_offenses, #currently_disabled_lines, #custom_severity, #default_severity, #disable_uncorrectable, #enabled_line?, #file_name_matches_any?, #find_message, #find_severity, #range_for_original, #range_from_node_or_range,
#reset_investigation

Actually private methods.

#use_corrector

::RuboCop::Cop::AutocorrectLogic - Included

::RuboCop::Cop::IgnoredNode - Included

Constructor Details

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

Class Method Details

.joining_forces

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/shadowing_outer_local_variable.rb', line 49

def self.joining_forces
  VariableForce
end

Instance Method Details

#before_declaring_variable(variable, variable_table)

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/shadowing_outer_local_variable.rb', line 53

def before_declaring_variable(variable, variable_table)
  return if variable.should_be_unused?
  return if ractor_block?(variable.scope.node)

  outer_local_variable = variable_table.find_variable(variable.name)
  return unless outer_local_variable
  return if same_conditions_node_different_branch?(variable, outer_local_variable)

  message = format(MSG, variable: variable.name)
  add_offense(variable.declaration_node, message: message)
end

#find_conditional_node_from_ascendant(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/shadowing_outer_local_variable.rb', line 89

def find_conditional_node_from_ascendant(node)
  return unless (parent = node.parent)
  return parent if parent.conditional?

  find_conditional_node_from_ascendant(parent)
end

#node_or_its_ascendant_conditional?(node) ⇒ Boolean

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/shadowing_outer_local_variable.rb', line 96

def node_or_its_ascendant_conditional?(node)
  return true if node.conditional?

  !!find_conditional_node_from_ascendant(node)
end

#ractor_block?(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/shadowing_outer_local_variable.rb', line 45

def_node_matcher :ractor_block?, <<~PATTERN
  (block (send (const nil? :Ractor) :new ...) ...)
PATTERN

#same_conditions_node_different_branch?(variable, outer_local_variable) ⇒ Boolean

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/shadowing_outer_local_variable.rb', line 65

def same_conditions_node_different_branch?(variable, outer_local_variable)
  variable_node = variable_node(variable)
  return false unless node_or_its_ascendant_conditional?(variable_node)

  outer_local_variable_node =
    find_conditional_node_from_ascendant(outer_local_variable.declaration_node)
  return true unless outer_local_variable_node
  return false unless outer_local_variable_node.conditional?
  return true if variable_node == outer_local_variable_node

  outer_local_variable_node.if_type? &&
    variable_node == outer_local_variable_node.else_branch
end

#variable_node(variable)

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/shadowing_outer_local_variable.rb', line 79

def variable_node(variable)
  parent_node = variable.scope.node.parent

  if parent_node.when_type?
    parent_node.parent
  else
    parent_node
  end
end