TypeError: debugging with --debug

[jakago]

main.rb

p JRUBY_VERSION

Environment

jruby 9.1.12.0 (2.3.3) 2017-06-15 33c6439 Java HotSpot(TM) 64-Bit Server VM 24.80-b11 on 1.7.0_80-b15 +jit [darwin-x86_64]

Darwin mac-mini.local 15.6.0 Darwin Kernel Version 15.6.0: Mon Jan 9 23:07:29 PST 2017; root:xnu-3248.60.11.2.1~1/RELEASE_X86_64 x86_64

Actual Behavior

OK:

% jruby main.rb
"9.1.12.0"

Warning:

% jruby -rdebug main.rb
Debug.rb
Emacs support available.

/Users/xxxxxx/.rbenv/versions/jruby-9.1.12.0/lib/ruby/stdlib/debug.rb:1114: warning: tracing
 (e.g. set_trace_func) will not capture all events without --debug flag
"9.1.12.0"

Error:

% jruby --debug -rdebug main.rb
Debug.rb
Emacs support available.

TypeError: no implicit conversion of Symbol into Integer
                   [] at org/jruby/RubyArray.java:1458
              context at /Users/xxxxxx/.rbenv/versions/jruby-9.1.12.0/lib/ruby/stdlib/debug.rb:982
     block in suspend at /Users/xxxxxx/.rbenv/versions/jruby-9.1.12.0/lib/ruby/stdlib/debug.rb:958
                 each at org/jruby/RubyHash.java:1343
     block in suspend at /Users/xxxxxx/.rbenv/versions/jruby-9.1.12.0/lib/ruby/stdlib/debug.rb:956
          synchronize at org/jruby/ext/thread/Mutex.java:148
              suspend at /Users/xxxxxx/.rbenv/versions/jruby-9.1.12.0/lib/ruby/stdlib/debug.rb:954
          suspend_all at /Users/xxxxxx/.rbenv/versions/jruby-9.1.12.0/lib/ruby/stdlib/debug.rb:237
           trace_func at /Users/xxxxxx/.rbenv/versions/jruby-9.1.12.0/lib/ruby/stdlib/debug.rb:865
  block in DEBUGGER__ at /Users/xxxxxx/.rbenv/versions/jruby-9.1.12.0/lib/ruby/stdlib/debug.rb:1115
               <main> at main.rb:1

[enebo]

wowie zowie!!! So glancing at this it would appear in most cases we pass in nothing or just the thread to context but SOMETIMES we pass in [thread, 1]. Very weird. In an award for most esoteric Ruby syntax of 2017 (and believe me I thought I knew pretty much all weird Ruby syntax):

        for th, in @thread_list
          next if th == Thread.current
          context(th).set_suspend
        end

Notice that ','? HAHAH so JRuby does not destructure the array because of that comma and passes the array through as th. It should just pass the first element. Trivial repro:

@t = [[1, 2], [3, 4]]
for th, in @t
   p th
end