DEVHIDE
Login Or Sign up

Why is the behaviour of begin-next-end different in ruby and jruby?

199 Views Asked by At

Compare the following scenarios (they are the same, but the outcome is different):

First I'll do it on ruby (cruby)

~> irb
irb(main):001:0> begin
irb(main):002:1* begin
irb(main):003:2* puts 1
irb(main):004:2> next
irb(main):005:2> end
irb(main):006:1> puts 2
irb(main):007:1> end
SyntaxError: (irb):4: Can't escape from eval with next

Now same thing on jruby:

~> jirb
irb(main):001:0> begin
irb(main):002:1* begin
irb(main):003:2* puts 1
irb(main):004:2> next
irb(main):005:2> end
irb(main):006:1> puts 2
irb(main):007:1> end
1
=> nil

Why doesn't this fail on jruby like it does on cruby? Is this a jruby bug?

ruby jruby
Original Q&A
2

There are 2 best solutions below

0
On BEST ANSWER

I filed this as Bug #13064.

I tested your code in a variety of versions of YARV, as well as on the latest versions of JRuby, MRuby, and Rubinius:

  • YARV 2.2.0 (the build shipping with macOS)

    # ruby -v -W -e 'begin; begin puts 1; next end; puts 2 end'
ruby 2.0.0p648 (2015-12-16 revision 53162) [universal.x86_64-darwin16]
-e:1: warning: statement not reached
-e:1: Invalid next
-e: compile error (SyntaxError)

# irb -f -d -w -W
irb(main):001:0> p RUBY_VERSION
"2.0.0"
=> "2.0.0"
irb(main):002:0> p RUBY_ENGINE
"ruby"
=> "ruby"
irb(main):003:0> 
irb(main):004:0* begin
irb(main):005:1*   begin
irb(main):006:2*     puts 1
irb(main):007:2>     next
irb(main):008:2>   end
irb(main):009:1>   puts 2
irb(main):010:1> end
(irb):9: warning: statement not reached
Exception `SyntaxError' at /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/irb/workspace.rb:86 - (irb):7: Can't escape from eval with next
Exception `SyntaxError' at /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/irb/workspace.rb:86 - (irb):7: Can't escape from eval with next
SyntaxError: (irb):7: Can't escape from eval with next
    from (irb)
irb(main):011:0> 
irb(main):012:0* exit

  • YARV 2.3.1 (the version JRuby claims to be compatible with at the moment)

    # ruby -v -W -e 'begin; begin puts 1; next end; puts 2 end'
ruby 2.3.1p112 (2016-04-26 revision 54768) [x86_64-darwin16]
-e:1: warning: statement not reached
-e: -e:1: Invalid next (SyntaxError)

# irb -f -d -w -W
irb(main):001:0> p RUBY_VERSION
"2.3.1"
=> "2.3.1"
irb(main):002:0> p RUBY_ENGINE
"ruby"
=> "ruby"
irb(main):003:0> 
irb(main):004:0* begin
irb(main):005:1*   begin
irb(main):006:2*     puts 1
irb(main):007:2>     next
irb(main):008:2>   end
irb(main):009:1>   puts 2
irb(main):010:1> end
(irb):9: warning: statement not reached
Exception `SyntaxError' at /Users/joerg/.rbenv/versions/2.3.1/lib/ruby/2.3.0/irb/workspace.rb:87 - (irb):7: Can't escape from eval with next
Exception `SyntaxError' at /Users/joerg/.rbenv/versions/2.3.1/lib/ruby/2.3.0/irb/workspace.rb:87 - (irb):7: Can't escape from eval with next
Exception `SyntaxError' at /Users/joerg/.rbenv/versions/2.3.1/lib/ruby/2.3.0/irb/workspace.rb:87 - (irb):7: Can't escape from eval with next
SyntaxError: (irb):7: Can't escape from eval with next
    from (irb)
irb(main):011:0> 
irb(main):012:0* exit

  • YARV 2.3.3

    # ruby -v -W -e 'begin; begin puts 1; next end; puts 2 end'
ruby 2.3.3p222 (2016-11-21 revision 56859) [x86_64-darwin16]
-e:1: warning: statement not reached
-e: -e:1: Invalid next (SyntaxError)

# irb -f -d -w -W
irb(main):001:0> p RUBY_VERSION
"2.3.3"
=> "2.3.3"
irb(main):002:0> p RUBY_ENGINE
"ruby"
=> "ruby"
irb(main):003:0> 
irb(main):004:0* begin
irb(main):005:1*   begin
irb(main):006:2*     puts 1
irb(main):007:2>     next
irb(main):008:2>   end
irb(main):009:1>   puts 2
irb(main):010:1> end
(irb):9: warning: statement not reached
Exception `SyntaxError' at /Users/joerg/.rbenv/versions/2.3.3/lib/ruby/2.3.0/irb/workspace.rb:87 - (irb):7: Can't escape from eval with next
Exception `SyntaxError' at /Users/joerg/.rbenv/versions/2.3.3/lib/ruby/2.3.0/irb/workspace.rb:87 - (irb):7: Can't escape from eval with next
Exception `SyntaxError' at /Users/joerg/.rbenv/versions/2.3.3/lib/ruby/2.3.0/irb/workspace.rb:87 - (irb):7: Can't escape from eval with next
SyntaxError: (irb):7: Can't escape from eval with next
    from (irb)
irb(main):011:0> 
irb(main):012:0* exit

  • YARV 2.4.0-preview3:

    # ruby -v -W -e 'begin; begin puts 1; next end; puts 2 end'
ruby 2.4.0preview3 (2016-11-07 trunk 56661) [x86_64-darwin16]
-e:1: warning: statement not reached
-e: -e:1: Invalid next (SyntaxError)

# irb -f -d -w -W
irb(main):001:0> p RUBY_VERSION
"2.4.0"
=> "2.4.0"
irb(main):002:0> p RUBY_ENGINE
"ruby"
=> "ruby"
irb(main):003:0> 
irb(main):004:0* begin
irb(main):005:1*   begin
irb(main):006:2*     puts 1
irb(main):007:2>     next
irb(main):008:2>   end
irb(main):009:1>   puts 2
irb(main):010:1> end
(irb):9: warning: statement not reached
Exception `SyntaxError' at /Users/joerg/.rbenv/versions/2.4.0-preview3/lib/ruby/2.4.0/irb/workspace.rb:87 - (irb):7: Can't escape from eval with next
SyntaxError: (irb):7: Can't escape from eval with next
    from (irb)
irb(main):011:0> 
irb(main):012:0* exit

  • YARV 2.4.0-dev (current SVN trunk as of yesterday):

    # ruby -v -W -e 'begin; begin puts 1; next end; puts 2 end'
ruby 2.4.0dev (2016-12-22 trunk 57151) [x86_64-darwin16]
-e:1: warning: statement not reached
-e: -e:1: Invalid next (SyntaxError)

# irb -f -d -w -W
irb(main):001:0> p RUBY_VERSION
"2.4.0"
=> "2.4.0"
irb(main):002:0> p RUBY_ENGINE
"ruby"
=> "ruby"
irb(main):003:0> 
irb(main):004:0* begin
irb(main):005:1*   begin
irb(main):006:2*     puts 1
irb(main):007:2>     next
irb(main):008:2>   end
irb(main):009:1>   puts 2
irb(main):010:1> end
(irb):9: warning: statement not reached
Exception `SyntaxError' at /Users/joerg/.rbenv/versions/2.4.0-dev/lib/ruby/2.4.0/irb/workspace.rb:87 - (irb):7: Can't escape from eval with next
SyntaxError: (irb):7: Can't escape from eval with next
    from (irb)
irb(main):011:0> 
irb(main):012:0* exit

  • Rubinius 3.69

    # rbx -v -W -e 'begin; begin puts 1; next end; puts 2 end'
rubinius 3.69 (2.3.1 a57071c6 2016-11-17 3.8.1) [x86_64-darwin15.6.0]
1
                main # Rubinius::Loader at core/loader.rb:860
               evals # Rubinius::Loader at core/loader.rb:646
                eval # Kernel(Rubinius::Loader) at core/kernel.rb:1130
    call_on_instance # Rubinius::BlockEnvironment at core/block_environment.rb:147
   { } in __script__ # Object at -e:1
          jump_error . Rubinius at core/rubinius.rb:279

invalid context for 'next' (LocalJumpError)

An exception occurred evaluating command line code

# irb
irb(main):001:0> p RUBY_VERSION
"2.3.1"
=> "2.3.1"
irb(main):002:0> p RUBY_ENGINE
"rbx"
=> "rbx"
irb(main):003:0> 
irb(main):004:0* begin
irb(main):005:1*   begin
irb(main):006:2*     puts 1
irb(main):007:2>     next
irb(main):008:2>   end
irb(main):009:1>   puts 2
irb(main):010:1> end
1
LocalJumpError: invalid context for 'next'
    from core/rubinius.rb:279:in `jump_error'
    from (irb):7
    from core/block_environment.rb:147:in `call_on_instance'
    from core/kernel.rb:1130:in `eval'
    from core/kernel.rb:585:in `loop'
    from core/proc.rb:20:in `call'
    from core/kernel.rb:1067:in `catch'
    from core/throw_catch.rb:8:in `register'
    from core/kernel.rb:1066:in `catch'
    from core/proc.rb:20:in `call'
    from core/kernel.rb:1067:in `catch'
    from core/throw_catch.rb:8:in `register'
    from core/kernel.rb:1066:in `catch'
    from core/code_loader.rb:505:in `load_script'
    from core/code_loader.rb:590:in `load_script'
    from core/loader.rb:679:in `script'
    from core/loader.rb:861:in `main'irb(main):011:0> 
irb(main):012:0* exit

  • JRuby 9.1.6.0 (the latest release)

    # jruby -v -W -e 'begin; begin puts 1; next end; puts 2 end'
jruby 9.1.6.0 (2.3.1) 2016-11-09 0150a76 Java HotSpot(TM) 64-Bit Server VM 25.102-b14 on 1.8.0_102-b14 +jit [darwin-x86_64]
1
LocalJumpError: unexpected next
  <main> at -e:1

# irb -f -d -w -W
irb(main):001:0> p RUBY_VERSION
"2.3.1"
=> "2.3.1"
irb(main):002:0> p RUBY_ENGINE
"jruby"
=> "jruby"
irb(main):003:0> 
irb(main):004:0* begin
irb(main):005:1*   begin
irb(main):006:2*     puts 1
irb(main):007:2>     next
irb(main):008:2>   end
irb(main):009:1>   puts 2
irb(main):010:1> end
1
=> nil
irb(main):011:0> 
irb(main):012:0* exit

  • MRuby 1.2.0 (the minimal ISO compliant Ruby implementation written by matz himself)

    # mruby -v -e 'begin; begin puts 1; next end; puts 2 end'
mruby 1.2.0 (2015-11-17) 
00001 NODE_SCOPE:
00001   NODE_BEGIN:
00001     NODE_BEGIN:
00001       NODE_BEGIN:
00001         NODE_CALL:
00001           NODE_SELF
00001           method='puts' (383)
00001           args:
00001             NODE_INT 1 base 10
00001         NODE_NEXT:
00001       NODE_CALL:
00001         NODE_SELF
00001         method='puts' (383)
00001         args:
00001           NODE_INT 2 base 10
irep 0x7fe0e3c1b630 nregs=4 nlocals=1 pools=1 syms=1 reps=0
file: -e
    1 000 OP_LOADSELF   R1      
    1 001 OP_LOADI  R2  1   
    1 002 OP_SEND   R1  :puts   1
    1 003 OP_ERR    "unexpected next"
    1 004 OP_LOADSELF   R1      
    1 005 OP_LOADI  R2  2   
    1 006 OP_SEND   R1  :puts   1
    1 007 OP_STOP

1
trace:
    [0] -e:1
LocalJumpError: unexpected next

# irb -v
mruby 1.2.0 (2015-11-17) 
mirb - Embeddable Interactive Ruby Shell

> p RUBY_VERSION
00001 NODE_SCOPE:
00001   NODE_BEGIN:
00001     NODE_CALL:
00001       NODE_SELF
00001       method='p' (384)
00001       args:
00001         NODE_CONST RUBY_VERSION
irep 0x7fceeac05220 nregs=4 nlocals=1 pools=0 syms=2 reps=0
file: (mirb)
    1 000 OP_LOADSELF   R1      
    1 001 OP_GETCONST   R2  :RUBY_VERSION
    1 002 OP_SEND   R1  :p  1
    1 003 OP_STOP

"1.9"
 => "1.9"
> p RUBY_ENGINE
00002 NODE_SCOPE:
00002   NODE_BEGIN:
00002     NODE_CALL:
00002       NODE_SELF
00002       method='p' (384)
00002       args:
00002         NODE_CONST RUBY_ENGINE
irep 0x7fceeae05cf0 nregs=4 nlocals=1 pools=0 syms=2 reps=0
file: (mirb)
    2 000 OP_LOADSELF   R1      
    2 001 OP_GETCONST   R2  :RUBY_ENGINE
    2 002 OP_SEND   R1  :p  1
    2 003 OP_STOP

"mruby"
 => "mruby"
> 
00004 NODE_SCOPE:
00004   NODE_BEGIN:
irep 0x7fceeac06a50 nregs=2 nlocals=1 pools=0 syms=0 reps=0
file: (mirb)
    4 000 OP_LOADNIL    R1      
    4 001 OP_STOP

 => nil
> begin
00005 NODE_NIL
*   begin
00007 NODE_NIL
*     puts 1
00009 NODE_NIL
*     next
00011 NODE_NIL
*   end
00013 NODE_NIL
*   puts 2
00015 NODE_NIL
* end
00012 NODE_SCOPE:
00012   NODE_BEGIN:
00012     NODE_BEGIN:
00012       NODE_BEGIN:
00012         NODE_CALL:
00012           NODE_SELF
00012           method='puts' (383)
00012           args:
00012             NODE_INT 1 base 10
00013         NODE_NEXT:
00015       NODE_CALL:
00015         NODE_SELF
00015         method='puts' (383)
00015         args:
00015           NODE_INT 2 base 10
irep 0x7fceeae01130 nregs=4 nlocals=1 pools=1 syms=1 reps=0
file: (mirb)
   12 000 OP_LOADSELF   R1      
   12 001 OP_LOADI  R2  1   
   12 002 OP_SEND   R1  :puts   1
   13 003 OP_ERR    "unexpected next"
   15 004 OP_LOADSELF   R1      
   15 005 OP_LOADI  R2  2   
   15 006 OP_SEND   R1  :puts   1
   15 007 OP_STOP

1
LocalJumpError: unexpected next
> 
00012 NODE_SCOPE:
00012   NODE_BEGIN:
irep 0x7fceeae078f0 nregs=2 nlocals=1 pools=0 syms=0 reps=0
file: (mirb)
   12 000 OP_LOADNIL    R1      
   12 001 OP_STOP

 => nil
> exit

What is most interesting is that MRuby, JRuby and Rubinius actually agree on the behavior, but differ from YARV. Either YARV or all the other ones are wrong. I cannot say which ones, though.

0
On

Around the Ruby 1.9 timeframe, MRI started to detect some of these illegal jump cases at parse time rather than raising LocalJumpError. JRuby, MRuby, and Rubinius likely still leave the jump in place and let it fail later on when invoked rather than raising a Syntax error right away.

It might be worth filing a bug with JRuby. Our parser is basically a port of MRIs so we should be able to raise the same error. Barring that, we can perform this analysis at compile time and raise the error then.

Related Questions in RUBY

Related Questions in JRUBY

Trending Questions

Popular # Hahtags

javascript python java c# php android html jquery c++ css ios sql mysql r reactjs node.js arrays c asp.net json python-3.x ruby-on-rails .net sql-server swift django angular objective-c pandas excel

Popular Questions

Copyright © 2021 Jogjafile Inc.