class RuboCop::Cop::Lint::ShadowedException


end
handle_standard_error
rescue Errno::EAGAIN, Errno::EWOULDBLOCK
something
begin
# the same error code.
# This good case is for ‘Errno::EAGAIN` and `Errno::EWOULDBLOCK` with
# the same error code or different error code depends on environment.
# For example, whether `Errno::EAGAIN` and `Errno::EWOULDBLOCK` are
# System dependent error code depends on runtime environment.
# This is a special case for system call errors.
#
# good, however depending on runtime environment.
end
handle_exception
rescue Exception
handle_standard_error
rescue StandardError
something
begin
# good
end
handle_standard_error
rescue StandardError
handle_exception
rescue Exception
something
begin
# bad
@example
exception is rescued.
less specific exception being rescued before a more specific
This cop checks for a rescued exception that get shadowed by a

def compare_exceptions(exception, other_exception) 

def compare_exceptions(exception, other_exception)
  if system_call_err?(exception) && system_call_err?(other_exception)
    # This condition logic is for special case.
    # System dependent error code depends on runtime environment.
    # For example, whether `Errno::EAGAIN` and `Errno::EWOULDBLOCK` are
    # the same error code or different error code depends on runtime
    # environment. This checks the error code for that.
    exception.const_get(:Errno) != other_exception.const_get(:Errno) &&
      exception <=> other_exception
  else
    exception && other_exception && exception <=> other_exception
  end
end

def contains_multiple_levels_of_exceptions?(group) 

def contains_multiple_levels_of_exceptions?(group)
  if group.size > 1 && group.include?(Exception)
    # Treat `Exception` as the highest level exception unless `nil` was
    # also rescued
    return !(group.size == 2 && group.include?(NilClass))
  end
  group.combination(2).any? do |a, b|
    compare_exceptions(a, b)
  end
end

def evaluate_exceptions(rescue_group) 

def evaluate_exceptions(rescue_group)
  if rescue_group
    rescued_exceptions = rescued_exceptions(rescue_group)
    rescued_exceptions.each_with_object([]) do |exception, converted|
      begin
        converted << Kernel.const_get(exception)
      rescue NameError
        converted << nil
      end
    end
  else
    # treat an empty `rescue` as `rescue StandardError`
    [StandardError]
  end
end

def offense_range(rescues) 

def offense_range(rescues)
  first_rescue = rescues.first
  last_rescue = rescues.last
  last_exceptions, = *last_rescue
  # last_rescue clause may not specify exception class
  end_pos = if last_exceptions
              last_exceptions.loc.expression.end_pos
            else
              last_rescue.loc.keyword.end_pos
            end
  range_between(first_rescue.loc.expression.begin_pos, end_pos)
end

def on_rescue(node) 

def on_rescue(node)
  return if rescue_modifier?(node)
  _body, *rescues, _else = *node
  rescued_groups = rescues.each_with_object([]) do |group, exceptions|
    rescue_group, = *group
    exceptions << evaluate_exceptions(rescue_group)
  end
  rescue_group_rescues_multiple_levels = rescued_groups.any? do |group|
    contains_multiple_levels_of_exceptions?(group)
  end
  return if !rescue_group_rescues_multiple_levels &&
            sorted?(rescued_groups)
  add_offense(node, location: offense_range(rescues))
end

def rescued_exceptions(rescue_group)

Parameters:
  • rescue_group (RuboCop::AST::Node) -- is a node of array_type 
def rescued_exceptions(rescue_group)
  klasses = *rescue_group
  klasses.map do |klass|
    next unless klass.const_type?
    klass.source
  end.compact
end

def sorted?(rescued_groups) 

def sorted?(rescued_groups)
  rescued_groups.each_cons(2).all? do |x, y|
    if x.include?(Exception)
      false
    elsif y.include?(Exception)
      true
    elsif x.none? || y.none?
      # consider sorted if a group is empty or only contains
      # `nil`s
      true
    else
      (x <=> y || 0) <= 0
    end
  end
end

def system_call_err?(error) 

def system_call_err?(error)
  error && error.ancestors[1] == SystemCallError
end