DotPosition cop breaks on lambda call with '.()'

[dirkbolte]

The following code results in an exception in the DotPosition cop:

# encoding: UTF-8
l = ->(p) { puts p }
l.(1)

Resulting callstack is:

An error occurred while DotPosition cop was inspecting /tmp/test.rb.
undefined method `line' for nil:NilClass
/home/dirkbolte/.rvm/gems/ruby-1.9.3-p392/gems/rubocop-0.10.0/lib/rubocop/cop/style/dot_position.rb:22:in `proper_dot_position?'
/home/dirkbolte/.rvm/gems/ruby-1.9.3-p392/gems/rubocop-0.10.0/lib/rubocop/cop/style/dot_position.rb:13:in `on_send'
/home/dirkbolte/.rvm/gems/ruby-1.9.3-p392/gems/rubocop-0.10.0/lib/rubocop/cop/commissioner.rb:80:in `delegate_to'
(eval):4:in `block in on_send'
(eval):2:in `each'
(eval):2:in `on_send'
/home/dirkbolte/.rvm/gems/ruby-1.9.3-p392/gems/ast-1.1.0/lib/ast/processor.rb:239:in `process'
/home/dirkbolte/.rvm/gems/ruby-1.9.3-p392/gems/ast-1.1.0/lib/ast/processor.rb:255:in `block in process_all'
/home/dirkbolte/.rvm/gems/ruby-1.9.3-p392/gems/ast-1.1.0/lib/ast/processor.rb:254:in `map'
/home/dirkbolte/.rvm/gems/ruby-1.9.3-p392/gems/ast-1.1.0/lib/ast/processor.rb:254:in `process_all'
/home/dirkbolte/.rvm/gems/ruby-1.9.3-p392/gems/parser-2.0.0.pre2/lib/parser/ast/processor.rb:6:in `process_regular_node'
(eval):8:in `on_begin'
/home/dirkbolte/.rvm/gems/ruby-1.9.3-p392/gems/ast-1.1.0/lib/ast/processor.rb:239:in `process'
/home/dirkbolte/.rvm/gems/ruby-1.9.3-p392/gems/rubocop-0.10.0/lib/rubocop/cop/commissioner.rb:54:in `investigate'
/home/dirkbolte/.rvm/gems/ruby-1.9.3-p392/gems/rubocop-0.10.0/lib/rubocop/cli.rb:109:in `inspect_file'
/home/dirkbolte/.rvm/gems/ruby-1.9.3-p392/gems/rubocop-0.10.0/lib/rubocop/cli.rb:58:in `block in run'
/home/dirkbolte/.rvm/gems/ruby-1.9.3-p392/gems/rubocop-0.10.0/lib/rubocop/cli.rb:52:in `each'
/home/dirkbolte/.rvm/gems/ruby-1.9.3-p392/gems/rubocop-0.10.0/lib/rubocop/cli.rb:52:in `run'
/home/dirkbolte/.rvm/gems/ruby-1.9.3-p392/gems/rubocop-0.10.0/bin/rubocop:14:in `block in <top (required)>'
/home/dirkbolte/.rvm/rubies/ruby-1.9.3-p392/lib/ruby/1.9.1/benchmark.rb:295:in `realtime'
/home/dirkbolte/.rvm/gems/ruby-1.9.3-p392/gems/rubocop-0.10.0/bin/rubocop:13:in `<top (required)>'
/home/dirkbolte/.rvm/gems/ruby-1.9.3-p392/bin/rubocop:19:in `load'
/home/dirkbolte/.rvm/gems/ruby-1.9.3-p392/bin/rubocop:19:in `<main>'
/home/dirkbolte/.rvm/gems/ruby-1.9.3-p392/bin/ruby_noexec_wrapper:14:in `eval'
/home/dirkbolte/.rvm/gems/ruby-1.9.3-p392/bin/ruby_noexec_wrapper:14:in `<main>'

Version information:
Mention the following information in the issue report:
0.10.0 (using Parser 2.0.0.pre2, running on ruby 1.9.3 x86_64-linux)

[dirkbolte]

Anyhow I wonder whether this syntax would be something to add as BAD for the ruby coding style.

[bbatsov]

Yep, it's not something I'd consider good style. l[1] is also pretty confusing since it looks a lot like element access. Please, create a ticket on the style guide so we won't forget to add a rule about this.