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Class: RuboCop::Cop::Lint::ShadowedArgument

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/shadowed_argument.rb

Overview

Checks for shadowed arguments.

This cop has IgnoreImplicitReferences configuration option. It means argument shadowing is used in order to pass parameters to zero arity super when IgnoreImplicitReferences is true.

Examples:

# bad
do_something do |foo|
  foo = 42
  puts foo
end

def do_something(foo)
  foo = 42
  puts foo
end

# good
do_something do |foo|
  foo = foo + 42
  puts foo
end

def do_something(foo)
  foo = foo + 42
  puts foo
end

def do_something(foo)
  puts foo
end

IgnoreImplicitReferences: false (default)

# bad
def do_something(foo)
  foo = 42
  super
end

def do_something(foo)
  foo = super
  bar
end

IgnoreImplicitReferences: true

# good
def do_something(foo)
  foo = 42
  super
end

def do_something(foo)
  foo = super
  bar
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/shadowed_argument.rb', line 72

def self.joining_forces
  VariableForce
end

Instance Attribute Details

#ignore_implicit_references?Boolean (readonly, private)

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/shadowed_argument.rb', line 171

def ignore_implicit_references?
  cop_config['IgnoreImplicitReferences']
end

Instance Method Details

#after_leaving_scope(scope, _variable_table)

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/shadowed_argument.rb', line 76

def after_leaving_scope(scope, _variable_table)
  scope.variables.each_value { |variable| check_argument(variable) }
end

#argument_references(argument) (private)

Get argument references without assignments' references

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/shadowed_argument.rb', line 161

def argument_references(argument)
  assignment_references = argument.assignments.flat_map(&:references).map(&:source_range)

  argument.references.reject do |ref|
    next false unless ref.explicit?

    assignment_references.include?(ref.node.source_range)
  end
end

#assignment_without_argument_usage(argument) (private)

Find the first argument assignment, which doesn’t reference the argument at the rhs. If the assignment occurs inside a branch or block, it is impossible to tell whether it’s executed, so precise shadowing location is not known.

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/shadowed_argument.rb', line 120

def assignment_without_argument_usage(argument)
  argument.assignments.reduce(true) do |location_known, assignment|
    assignment_node = assignment.meta_assignment_node || assignment.node

    # Shorthand assignments always use their arguments
    next false if assignment_node.shorthand_asgn?
    next false unless assignment_node.parent

    node_within_block_or_conditional =
      node_within_block_or_conditional?(assignment_node.parent, argument.scope.node)

    unless uses_var?(assignment_node, argument.name)
      # It's impossible to decide whether a branch or block is executed,
      # so the precise reassignment location is undecidable.
      next false if node_within_block_or_conditional

      yield(assignment.node, location_known)
      break
    end

    location_known
  end
end

#check_argument(argument) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/shadowed_argument.rb', line 82

def check_argument(argument)
  return unless argument.method_argument? || argument.block_argument?
  # Block local variables, i.e., variables declared after ; inside
  # |...| aren't really arguments.
  return if argument.explicit_block_local_variable?

  shadowing_assignment(argument) do |node|
    message = format(MSG, argument: argument.name)

    add_offense(node, message: message)
  end
end

#node_within_block_or_conditional?(node, stop_search_node) ⇒ Boolean (private)

Check whether the given node is nested into block or conditional.

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/shadowed_argument.rb', line 152

def node_within_block_or_conditional?(node, stop_search_node)
  return false if node == stop_search_node

  node.conditional? || node.block_type? ||
    node_within_block_or_conditional?(node.parent, stop_search_node)
end

#reference_pos(node) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/shadowed_argument.rb', line 144

def reference_pos(node)
  node = node.parent if node.parent.masgn_type?

  node.source_range.begin_pos
end

#shadowing_assignment(argument) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/shadowed_argument.rb', line 95

def shadowing_assignment(argument)
  return unless argument.referenced?

  assignment_without_argument_usage(argument) do |node, location_known|
    assignment_without_usage_pos = node.source_range.begin_pos

    references = argument_references(argument)

    # If argument was referenced before it was reassigned
    # then it's not shadowed
    next if references.any? do |reference|
      next true if !reference.explicit? && ignore_implicit_references?

      reference_pos(reference.node) <= assignment_without_usage_pos
    end

    yield location_known ? node : argument.declaration_node
  end
end

#uses_var?(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/lint/shadowed_argument.rb', line 70

def_node_search :uses_var?, '(lvar %)'