nil-reference exception in AlignHash

[jfredett]

I received the following exception on the following code:

Code:

# encoding: utf-8
module Dugout
  module Math
    module Parser
      class Model
        include Katuv::Node
        multiple PrimitiveOp
        multiple DerivedOp
      end
    end

    module Model
      def self.model(name = nil, opts = {}, &block)
        Parser::Model.new(name, opts.merge(parent: nil), &block)
      end
    end
  end
end

The output of rubocop -d was

For /Users/jfredett/code/mine/dugout: configuration from /Users/jfredett/code/mine/dugout/.rubocop.yml
Default configuration from /Users/jfredett/.rvm/gems/rbx-head@dugout/gems/rubocop-0.13.0/config/default.yml
Inheriting configuration from /Users/jfredett/.rvm/gems/rbx-head@dugout/gems/rubocop-0.13.0/config/enabled.yml
Inheriting configuration from /Users/jfredett/.rvm/gems/rbx-head@dugout/gems/rubocop-0.13.0/config/disabled.yml
Inspecting 32 files
Scanning /Users/jfredett/code/mine/dugout/lib/dugout.rb
.Scanning /Users/jfredett/code/mine/dugout/spec/spec_helper.rb
.Scanning /Users/jfredett/code/mine/dugout/spec/shared/op_compiler_examples.rb
.Scanning /Users/jfredett/code/mine/dugout/spec/unit/math/model/definition_spec.rb
.Scanning /Users/jfredett/code/mine/dugout/spec/unit/math/model/reifier_spec.rb
.Scanning /Users/jfredett/code/mine/dugout/spec/unit/math/parser/*_spec.rb
.Scanning /Users/jfredett/code/mine/dugout/spec/integration/math/model/expression_evaluator_spec.rb
.Scanning /Users/jfredett/code/mine/dugout/spec/integration/math/model/expression_language_spec.rb
.Scanning /Users/jfredett/code/mine/dugout/spec/integration/math/model/op_compiler_spec.rb
.Scanning /Users/jfredett/code/mine/dugout/lib/dugout/math.rb
.Scanning /Users/jfredett/code/mine/dugout/lib/dugout/version.rb
.Scanning /Users/jfredett/code/mine/dugout/lib/dugout/math/model.rb
.Scanning /Users/jfredett/code/mine/dugout/lib/dugout/math/parser.rb
.Scanning /Users/jfredett/code/mine/dugout/lib/dugout/math/model/ast.rb
.Scanning /Users/jfredett/code/mine/dugout/lib/dugout/math/model/definition.rb
.Scanning /Users/jfredett/code/mine/dugout/lib/dugout/math/model/op_compiler.rb
.Scanning /Users/jfredett/code/mine/dugout/lib/dugout/math/model/reifier.rb
.Scanning /Users/jfredett/code/mine/dugout/lib/dugout/math/parser/attribute.rb
.Scanning /Users/jfredett/code/mine/dugout/lib/dugout/math/parser/display_function.rb
.Scanning /Users/jfredett/code/mine/dugout/lib/dugout/math/parser/implementation.rb
.Scanning /Users/jfredett/code/mine/dugout/lib/dugout/math/parser/model.rb
An error occurred while AlignHash cop was inspecting /Users/jfredett/code/mine/dugout/lib/dugout/math/parser/model.rb.
undefined method `loc' on nil:NilClass.
kernel/delta/kernel.rb:81:in `loc (method_missing)'
/Users/jfredett/.rvm/gems/rbx-head@dugout/gems/rubocop-0.13.0/lib/rubocop/cop/style/align_hash.rb:125:in `value_delta'
/Users/jfredett/.rvm/gems/rbx-head@dugout/gems/rubocop-0.13.0/lib/rubocop/cop/style/align_hash.rb:22:in `on_hash'
(eval):5:in `on_hash'
/Users/jfredett/.rvm/gems/rbx-head@dugout/gems/rubocop-0.13.0/lib/rubocop/cop/commissioner.rb:88:in `with_cop_error_handling'
(eval):4:in `on_hash'
kernel/bootstrap/array.rb:68:in `each'
(eval):2:in `on_hash'
/Users/jfredett/.rvm/gems/rbx-head@dugout/gems/ast-1.1.0/lib/ast/processor.rb:239:in `process'
/Users/jfredett/.rvm/gems/rbx-head@dugout/gems/ast-1.1.0/lib/ast/processor.rb:255:in `process_all'
kernel/bootstrap/array19.rb:18:in `map'
/Users/jfredett/.rvm/gems/rbx-head@dugout/gems/ast-1.1.0/lib/ast/processor.rb:254:in `process_all'
/Users/jfredett/.rvm/gems/rbx-head@dugout/gems/parser-2.0.0.pre8/lib/parser/ast/processor.rb:144:in `on_send'
(eval):9:in `on_send'
/Users/jfredett/.rvm/gems/rbx-head@dugout/gems/ast-1.1.0/lib/ast/processor.rb:239:in `process'
/Users/jfredett/.rvm/gems/rbx-head@dugout/gems/ast-1.1.0/lib/ast/processor.rb:255:in `process_all'
kernel/bootstrap/array19.rb:18:in `map'
/Users/jfredett/.rvm/gems/rbx-head@dugout/gems/ast-1.1.0/lib/ast/processor.rb:254:in `process_all'
/Users/jfredett/.rvm/gems/rbx-head@dugout/gems/parser-2.0.0.pre8/lib/parser/ast/processor.rb:144:in `on_send'
(eval):9:in `on_send'
/Users/jfredett/.rvm/gems/rbx-head@dugout/gems/ast-1.1.0/lib/ast/processor.rb:239:in `process'
/Users/jfredett/.rvm/gems/rbx-head@dugout/gems/parser-2.0.0.pre8/lib/parser/ast/processor.rb:132:in `on_defs'
(eval):9:in `on_defs'
/Users/jfredett/.rvm/gems/rbx-head@dugout/gems/ast-1.1.0/lib/ast/processor.rb:239:in `process'
/Users/jfredett/.rvm/gems/rbx-head@dugout/gems/ast-1.1.0/lib/ast/processor.rb:255:in `process_all'
kernel/bootstrap/array19.rb:18:in `map'
/Users/jfredett/.rvm/gems/rbx-head@dugout/gems/ast-1.1.0/lib/ast/processor.rb:254:in `process_all'
/Users/jfredett/.rvm/gems/rbx-head@dugout/gems/parser-2.0.0.pre8/lib/parser/ast/processor.rb:9:in `on_module (process_regular_node)'
(eval):9:in `on_module'
/Users/jfredett/.rvm/gems/rbx-head@dugout/gems/ast-1.1.0/lib/ast/processor.rb:239:in `process'
/Users/jfredett/.rvm/gems/rbx-head@dugout/gems/ast-1.1.0/lib/ast/processor.rb:255:in `process_all'
kernel/bootstrap/array19.rb:18:in `map'
/Users/jfredett/.rvm/gems/rbx-head@dugout/gems/ast-1.1.0/lib/ast/processor.rb:254:in `process_all'
/Users/jfredett/.rvm/gems/rbx-head@dugout/gems/parser-2.0.0.pre8/lib/parser/ast/processor.rb:9:in `on_begin (process_regular_node)'
(eval):9:in `on_begin'
/Users/jfredett/.rvm/gems/rbx-head@dugout/gems/ast-1.1.0/lib/ast/processor.rb:239:in `process'
/Users/jfredett/.rvm/gems/rbx-head@dugout/gems/ast-1.1.0/lib/ast/processor.rb:255:in `process_all'
kernel/bootstrap/array19.rb:18:in `map'
/Users/jfredett/.rvm/gems/rbx-head@dugout/gems/ast-1.1.0/lib/ast/processor.rb:254:in `process_all'
/Users/jfredett/.rvm/gems/rbx-head@dugout/gems/parser-2.0.0.pre8/lib/parser/ast/processor.rb:9:in `on_module (process_regular_node)'
(eval):9:in `on_module'
/Users/jfredett/.rvm/gems/rbx-head@dugout/gems/ast-1.1.0/lib/ast/processor.rb:239:in `process'
/Users/jfredett/.rvm/gems/rbx-head@dugout/gems/ast-1.1.0/lib/ast/processor.rb:255:in `process_all'
kernel/bootstrap/array19.rb:18:in `map'
/Users/jfredett/.rvm/gems/rbx-head@dugout/gems/ast-1.1.0/lib/ast/processor.rb:254:in `process_all'
/Users/jfredett/.rvm/gems/rbx-head@dugout/gems/parser-2.0.0.pre8/lib/parser/ast/processor.rb:9:in `on_module (process_regular_node)'
(eval):9:in `on_module'
/Users/jfredett/.rvm/gems/rbx-head@dugout/gems/ast-1.1.0/lib/ast/processor.rb:239:in `process'
/Users/jfredett/.rvm/gems/rbx-head@dugout/gems/rubocop-0.13.0/lib/rubocop/cop/commissioner.rb:56:in `investigate'
/Users/jfredett/.rvm/gems/rbx-head@dugout/gems/rubocop-0.13.0/lib/rubocop/cop/team.rb:45:in `inspect_file'
/Users/jfredett/.rvm/gems/rbx-head@dugout/gems/rubocop-0.13.0/lib/rubocop/cli.rb:87:in `inspect_file'
/Users/jfredett/.rvm/gems/rbx-head@dugout/gems/rubocop-0.13.0/lib/rubocop/cli.rb:48:in `run'
kernel/bootstrap/array.rb:68:in `each'
/Users/jfredett/.rvm/gems/rbx-head@dugout/gems/rubocop-0.13.0/lib/rubocop/cli.rb:42:in `run'
/Users/jfredett/.rvm/gems/rbx-head@dugout/gems/rubocop-0.13.0/bin/rubocop:14:in `__script__'
/Users/jfredett/.rvm/rubies/rbx-head/lib/benchmark.rb:304:in `measure'
/Users/jfredett/.rvm/rubies/rbx-head/lib/benchmark.rb:318:in `realtime'
/Users/jfredett/.rvm/gems/rbx-head@dugout/gems/rubocop-0.13.0/bin/rubocop:13:in `__script__'
kernel/common/kernel.rb:579:in `load'
/Users/jfredett/.rvm/gems/rbx-head@dugout/bin/rubocop:23:in `__script__'
kernel/common/block_environment.rb:55:in `call_on_instance'
kernel/common/eval.rb:74:in `eval'
/Users/jfredett/.rvm/gems/rbx-head@dugout/bin/ruby_noexec_wrapper:14:in `__script__'
kernel/delta/codeloader.rb:68:in `load_script'
kernel/delta/codeloader.rb:119:in `load_script'
kernel/loader.rb:645:in `script'
kernel/loader.rb:844:in `main'
.Scanning /Users/jfredett/code/mine/dugout/lib/dugout/math/parser/op.rb
.Scanning /Users/jfredett/code/mine/dugout/lib/dugout/math/parser/operator.rb
.Scanning /Users/jfredett/code/mine/dugout/lib/dugout/math/model/ast/addition.rb
.Scanning /Users/jfredett/code/mine/dugout/lib/dugout/math/model/ast/exponential.rb
.Scanning /Users/jfredett/code/mine/dugout/lib/dugout/math/model/ast/literal.rb
.Scanning /Users/jfredett/code/mine/dugout/lib/dugout/math/model/ast/log.rb
.Scanning /Users/jfredett/code/mine/dugout/lib/dugout/math/model/ast/multiplication.rb
.Scanning /Users/jfredett/code/mine/dugout/lib/dugout/math/model/ast/power.rb
.Scanning /Users/jfredett/code/mine/dugout/lib/dugout/math/model/ast/sqrt.rb
.Scanning /Users/jfredett/code/mine/dugout/lib/dugout/math/model/ast/subtraction.rb
.Scanning /Users/jfredett/code/mine/dugout/lib/dugout/math/model/ast/variable.rb
.

32 files inspected, no offences detected

1 error occurred:
An error occurred while AlignHash cop was inspecting /Users/jfredett/code/mine/dugout/lib/dugout/math/parser/model.rb.
Errors are usually caused by RuboCop bugs.
Please, report your problems to RuboCop's issue tracker.
Mention the following information in the issue report:
0.13.0 (using Parser 2.0.0.pre8, running on rbx 1.9.3 x86_64-apple-darwin12.3.0)
Finished in 2.597456932067871 seconds

I also tried (and received the same failure) on 1.9.3 and 2.0.0, latest patches -- this failure is on Rubinius. The trace requested that I post it here, I feel like this is something someone probably has run into before, but I didn't see any issues after a bit of searching that were similar.

[bbatsov]

This particular cop is new, so you might very well be the first person who has encountered this problem. @jonas054 would you take a look at it?

[bbatsov]

Btw, it's likely something Rubinius specific, since I cannot reproduce the bug with MRI 1.9, MRI 2.0 and JRuby 1.7.4.

[jonas054]

OK, I'll see what I can do.

[jfredett]

I was able to reproduce it on both 1.9 and 2.0 MRI, I'll add dumps in a gist (since they're big), and link it shortly (my internet is spotty at the moment). You should also be able to reproduce it by running rubocop -d on my project jfredett/dugout, as of SHA 13ccbee (the current master).

[jfredett]

The gist: https://gist.github.com/jfredett/6623274

[jonas054]

Thanks @jfredett for the detailed description of the error!

[jfredett]

No problem, I poked around the cop-code a bit, but haven't had opportunity to try to fix it. My guess is that it's because the particular line is of the form:

foo.bar(key: nil).other_thing

and in particular, the bar(key: nil) is confusing the cop.

[jonas054]

Yes, you're in the right place. I've found the problem and will make a pull request shortly.