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Class: RuboCop::Cop::Lint::UnreachableCode

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

Overview

Checks for unreachable code. The check are based on the presence of flow of control statement in non-final position in begin (implicit) blocks.

Examples:

# bad
def some_method
  return
  do_something
end

# bad
def some_method
  if cond
    return
  else
    return
  end
  do_something
end

# good
def some_method
  do_something
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 a 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

::RuboCop::Cop::Base - Inherited

#active_support_extensions_enabled?, #always_autocorrect?, #config, #config_to_allow_offenses, #config_to_allow_offenses=, #contextual_autocorrect?, #processed_source, #string_literals_frozen_by_default?, #target_satisfies_all_gem_version_requirements?

::RuboCop::Cop::AutocorrectLogic - Included

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

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_gem_version

Returns a gems locked versions (i.e.
#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

#disable_offense, #disable_offense_at_end_of_line, #disable_offense_before_and_after, #disable_offense_with_eol_or_surround_comment, #eol_comment, #eol_comment_would_be_inside_literal?, #heredoc_range, #line_with_eol_comment_too_long?, #max_line_length, #multiline_ranges, #multiline_string?,
#range_by_lines

Expand the given range to include all of any lines it covers.
#range_of_first_line, #string_continuation?, #surrounding_heredoc?, #surrounding_percent_array?

::RuboCop::Cop::IgnoredNode - Included

#ignore_node, #ignored_node?, #part_of_ignored_node?, #ignored_nodes

Constructor Details

.new(config = nil, options = nil) ⇒ UnreachableCode

[ GitHub ] 

  


# File 'lib/rubocop/cop/lint/unreachable_code.rb', line 35



def initialize(config = nil, options = nil)
  super
  @redefined = []
  @instance_eval_count = 0
end


  







Instance Method Details



  

    #after_block(node)  
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/unreachable_code.rb', line 48



def after_block(node)
  @instance_eval_count -= 1 if instance_eval_block?(node)
end


  








  

    #check_case(node)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/unreachable_code.rb', line 105



def check_case(node)
  else_branch = node.else_branch
  return false unless else_branch
  return false unless flow_expression?(else_branch)

  branches = node.case_type? ? node.when_branches : node.in_pattern_branches

  branches.all? { |branch| branch.body && flow_expression?(branch.body) }
end


  








  

    #check_if(node)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/unreachable_code.rb', line 99



def check_if(node)
  if_branch = node.if_branch
  else_branch = node.else_branch
  if_branch && else_branch && flow_expression?(if_branch) && flow_expression?(else_branch)
end


  








  

    #flow_command?(node)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/unreachable_code.rb', line 71



def_node_matcher :flow_command?, <<~PATTERN
  {
    return next break retry redo
    (send
     {nil? (const {nil? cbase} :Kernel)}
     #redefinable_flow_method?
     ...)
  }
PATTERN


  








  

    #flow_expression?(node)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/unreachable_code.rb', line 81



def flow_expression?(node)
  return report_on_flow_command?(node) if flow_command?(node)

  case node.type
  when :begin, :kwbegin
    expressions = *node
    expressions.any? { |expr| flow_expression?(expr) }
  when :if
    check_if(node)
  when :case, :case_match
    check_case(node)
  when :def
    register_redefinition(node)
  else
    false
  end
end


  








  

    #instance_eval_block?(node)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


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



def instance_eval_block?(node)
  node.any_block_type? && node.method?(:instance_eval)
end


  








  

    #on_begin(node)  
    Also known as: #on_kwbegin
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/unreachable_code.rb', line 52



def on_begin(node)
  expressions = *node

  expressions.each_cons(2) do |expression1, expression2|
    next unless flow_expression?(expression1)

    add_offense(expression2)
  end
end


  








  

    #on_block(node)  
    Also known as: #on_numblock, #on_itblock
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/unreachable_code.rb', line 41



def on_block(node)
  @instance_eval_count += 1 if instance_eval_block?(node)
end


  








  

    #on_itblock(node)  
  



  

    


Alias for #on_block.



  



  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/unreachable_code.rb', line 46



alias on_itblock on_block


  








  

    #on_kwbegin(node)  
  



  

    


Alias for #on_begin.



  



  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/unreachable_code.rb', line 62



alias on_kwbegin on_begin


  








  

    #on_numblock(node)  
  



  

    


Alias for #on_block.



  



  [ GitHub ]


  

  


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



alias on_numblock on_block


  








  

    #redefinable_flow_method?(method)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/unreachable_code.rb', line 66



def redefinable_flow_method?(method)
  %i[raise fail throw exit exit! abort].include? method
end


  








  

    #register_redefinition(node)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/unreachable_code.rb', line 115



def register_redefinition(node)
  @redefined << node.method_name if redefinable_flow_method? node.method_name
  false
end


  








  

    #report_on_flow_command?(node)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/unreachable_code.rb', line 124



def report_on_flow_command?(node)
  return true unless node.send_type?

  # By the contract of this function, this case means that
  # the method is called on `Kernel` in which case we
  # always want to report a warning.
  return true if node.receiver

  # Inside an `instance_eval` we have no way to tell the
  # type of `self` just by looking at the AST, so we can't
  # tell if the give function that's called has been
  # redefined or not, so to avoid false positives, we silence
  # the warning.
  return false if @instance_eval_count.positive?

  !@redefined.include? node.method_name
end