Bug #21551: Ractor isolation error points to the wrong place

• Status: Open
• Assignee: -
• Target version: -
• Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN

[tenderlovemaking (Aaron Patterson)]

The following code has a bug in it. The block passed to Ractor.new references the outer channel variable, so it can't be isolated. The problem is that I forgot to add |channel| to the block:

channel = Ractor::Port.new

coordinator = Ractor.new(channel) do
  inbound_work = Ractor::Port.new
  channel << inbound_work
end

However, the exception this raises is strange:

> ruby thing.rb
thing.rb:3: warning: Ractor is experimental, and the behavior may change in future versions of Ruby! Also there are many implementation issues.
thing.rb:3:in 'Ractor.new': can not isolate a Proc because it accesses outer variables (channel). (ArgumentError)

coordinator = Ractor.new(channel) do
                         ^^^^^^^
	from thing.rb:3:in '<main>'

I would expect the channel local inside the block to be underlined instead of the parameter passed to Ractor.new.