kwargs in Array.each mutates argument #5788
Description
Environment
$ bash jruby-9000.dev-SNAPSHOT/bin/jruby --version
jruby 9000.dev-SNAPSHOT (2.1.2p142) 2014-09-04 177ed02 Java HotSpot(TM) 64-Bit Server VM 25.181-b13 on 1.8.0_181-b13 [linux-amd64]
09:56:01 ~/repro
$ uname -a
Linux amacleay-cht-tp 4.15.0-54-generic #58-Ubuntu SMP Mon Jun 24 10:55:24 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux
Script:
# $ cat repro.rb
list = Array.new(200, { a: 1, b: 2, c: 3 })
list.each do |a:, b:, **|
puts "#{a} #{b}"
endExpected Behavior
It should print 1 2 200 times and exit happily, as does MRI:
$ rvm ruby-2.5.0 do ruby repro.rb | nl | tail -n1
200 1 2
Actual Behavior
Runs once and then fails. Further investigation shows that the runtime is mutating the invocant to .each
$ bash jruby-9000.dev-SNAPSHOT/bin/jruby repro.rb
1 2
ArgumentError: missing keyword: a
(root) at repro.rb:2
each at org/jruby/RubyArray.java:1546
(root) at repro.rb:2
More recent releases run a variable number of iterations and then fail:
9.2.5.0:
$ rvm jruby-9.2.5.0 do ruby repro.rb | nl | tail -n1
ArgumentError: missing keyword: a
<main> at repro.rb:2
each at org/jruby/RubyArray.java:1792
<main> at repro.rb:2
177 1 2
10:03:08 ~/repro
$ rvm jruby-9.2.5.0 do ruby repro.rb | nl | tail -n1
ArgumentError: missing keyword: a
<main> at repro.rb:2
each at org/jruby/RubyArray.java:1792
<main> at repro.rb:2
143 1 2
10:03:13 ~/repro
$ rvm jruby-9.2.5.0 do ruby repro.rb | nl | tail -n1
ArgumentError: missing keyword: a
<main> at repro.rb:2
each at org/jruby/RubyArray.java:1792
<main> at repro.rb:2
142 1 2
9.2.7.0:
$ rvm jruby-9.2.7.0 do ruby repro.rb | nl | tail -n1
ArgumentError: missing keyword: a
<main> at repro.rb:2
each at org/jruby/RubyArray.java:1792
<main> at repro.rb:2
151 1 2
10:03:38 ~/repro
$ rvm jruby-9.2.7.0 do ruby repro.rb | nl | tail -n1
ArgumentError: missing keyword: a
<main> at repro.rb:2
each at org/jruby/RubyArray.java:1792
<main> at repro.rb:2
193 1 2
10:03:42 ~/repro
$ rvm jruby-9.2.7.0 do ruby repro.rb | nl | tail -n1
ArgumentError: missing keyword: a
<main> at repro.rb:2
each at org/jruby/RubyArray.java:1792
<main> at repro.rb:2
171 1 2