Passing block explicitly to superclass method fails

[wied03]

At one point this worked (or maybe was not fully working) in Opal 0.9 but now it complains:

class SuperClass
  def add_stub(&block)
    puts 'super method, calling block'
    block.call
  end
end

class InheritingClass < SuperClass
  def add_stub(*args, &block)
    super(*args, &block)
  end
end

InheritingClass.new.add_stub do
  puts 'block ran'
end

Runs OK in MRI. It does not happen with a standalone method nor does it happen when 1 method calls another in the same fashion, just when calling the superclass' method. This also causes arity checking to break.

MRI:

super method, calling block
block ran

Opal:

super method, calling block

/tmp/opal-nodejs-runner-20151209-19233-13hhbbd:4249
      throw exception;
            ^
call: undefined method `call' for nil
    at OpalClass.Opal.defs.self [as $new] (/tmp/opal-nodejs-runner-20151209-19233-13hhbbd:4466:15)
    at NilClass.Opal.defn.TMP_1 (/tmp/opal-nodejs-runner-20151209-19233-13hhbbd:3028:54)
    at NilClass.method_missing_stub [as $call] (/tmp/opal-nodejs-runner-20151209-19233-13hhbbd:888:35)
    at $InheritingClass.Opal.defn.TMP_1 (/tmp/opal-nodejs-runner-20151209-19233-13hhbbd:19037:20)
    at $InheritingClass.Opal.defn.TMP_2 [as $add_stub] (/tmp/opal-nodejs-runner-20151209-19233-13hhbbd:19056:72)
    at Opal.dynamic_require_severity (/tmp/opal-nodejs-runner-20151209-19233-13hhbbd:19061:66)
    at Object.<anonymous> (/tmp/opal-nodejs-runner-20151209-19233-13hhbbd:19062:3)
    at Module._compile (module.js:456:26)
    at Object.Module._extensions..js (module.js:474:10)
    at Module.load (module.js:356:32)

[elia]

the number -4 is right (confirmed on cruby) so the problem must reside in the check:

opal/lib/opal/nodes/def.rb

Lines 238 to 267 in 3d5f8d3

	# Returns code used in debug mode to check arity of method call
	def arity_check(args, opt, splat, kwargs, block_name, mid)
	meth = mid.to_s.inspect
	arity = args.size - 1
	arity -= (opt.size)
	arity -= 1 if splat
	arity -= (kwargs.size)
	arity -= 1 if block_name
	arity = -arity - 1 if !opt.empty? or !kwargs.empty? or splat
	# $arity will point to our received arguments count
	aritycode = "var $arity = arguments.length;"
	if arity < 0 # splat or opt args
	min_arity = -(arity + 1)
	max_arity = args.size - 1
	max_arity -= 1 if block_name
	checks = []
	checks << "$arity < #{min_arity}" if min_arity > 0
	checks << "$arity > #{max_arity}" if max_arity and not(splat)
	aritycode + "if (#{checks.join(' || ')}) { Opal.ac($arity, #{arity}, this, #{meth}); }" if checks.size > 0
	else
	aritycode + "if ($arity !== #{arity}) { Opal.ac($arity, #{arity}, this, #{meth}); }"
	end
	end
	end

[wied03]

Looks like in the superclass case, the block isn't in TMP_1.$$p, it's the last argument in arguments, which causes arguments to be of length 5 instead of the 4 it's expecting

[wied03]

In a way, this has nothing to do with arity checking. If I disable arity checking, then the code fails because block in the add_stub method is nil

[elia]

So it's more like the arity check message can be improved…

[wied03]

Maybe. The bigger problem is the block thing. This reminds me of #1132.