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

Inherits:
Base
  • Object
show all
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:

[source,ruby]
----
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 collapse

MSG = 
'Shadowing outer local variable - `%<variable>s`.'

Constants inherited from Base

Base::RESTRICT_ON_SEND

Instance Attribute Summary

Attributes inherited from Base

#config, #processed_source

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from Base

#active_support_extensions_enabled?, #add_global_offense, #add_offense, autocorrect_incompatible_with, badge, #begin_investigation, 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, #inspect, 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?, #autocorrect_with_disable_uncorrectable?, #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

Class Method Details

.joining_forces ⇒ Object 



53
54
55
 
# File 'lib/rubocop/cop/lint/shadowing_outer_local_variable.rb', line 53

def self.joining_forces
  VariableForce
end

Instance Method Details

#before_declaring_variable(variable, variable_table) ⇒ Object 



57
58
59
60
61
62
63
64
65
66
67
 
# File 'lib/rubocop/cop/lint/shadowing_outer_local_variable.rb', line 57

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) ⇒ Object 



93
94
95
96
97
98
 
# File 'lib/rubocop/cop/lint/shadowing_outer_local_variable.rb', line 93

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

Returns:

  • (Boolean) 


100
101
102
103
104
 
# File 'lib/rubocop/cop/lint/shadowing_outer_local_variable.rb', line 100

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

  !!find_conditional_node_from_ascendant(node)
end

#ractor_block?(node) ⇒ Object 



49
50
51
 
# File 'lib/rubocop/cop/lint/shadowing_outer_local_variable.rb', line 49

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

#same_conditions_node_different_branch?(variable, outer_local_variable) ⇒ Boolean

Returns:

  • (Boolean) 


69
70
71
72
73
74
75
76
77
78
79
80
81
 
# File 'lib/rubocop/cop/lint/shadowing_outer_local_variable.rb', line 69

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) ⇒ Object 



83
84
85
86
87
88
89
90
91
 
# File 'lib/rubocop/cop/lint/shadowing_outer_local_variable.rb', line 83

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

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