Question

比较以下场景（它们是相同的，但结果不同）：

首先我会在ruby（cruby）

上做

~> 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

现在同样的事情在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

为什么这不会像在cruby上那样在jruby上失败？这是一个犹豫不决的虫子吗？

Answer 1

我将此归档为Bug #13064。

我在各种版本的YARV以及JRuby，MRuby和Rubinius的最新版本中测试了您的代码：

YARV 2.2.0（使用macOS进行构建）

<ion-content>
  <ion-list>
    <ion-item *ngFor="let item of array">{{item.name}}</ion-item>
  </ion-list>
</ion-content>
<ion-footer>
  <ion-searchbar (ionInput)="search()"></ion-searchbar>
</ion-footer>

YARV 2.3.1（JRuby声称此版本兼容）

# 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 2.3.3

# 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 2.4.0-preview3：

# 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-dev（截至昨天的当前SVN主干）：

# 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

Rubinius 3.69

# 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

JRuby 9.1.6.0（最新版本）

# 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

MRuby 1.2.0（由matz自己编写的最低ISO兼容的Ruby实现）

# 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

最有趣的是，MRuby，JRuby和Rubinius实际上都同意这种行为，但与YARV不同。 YARV或其他所有都是错的。不过，我不能说出哪些。

Answer 2

在Ruby 1.9时间范围内，MRI开始在分析时检测到一些非法跳转案例，而不是引发LocalJumpError。 JRuby，MRuby和Rubinius可能仍会保留跳转，并在调用时让它失败，而不是立即引发语法错误。

可能值得提交JRuby的错误。我们的解析器基本上是MRI的端口，所以我们应该能够引发相同的错误。除此之外，我们可以在编译时执行此分析，然后提出错误。

为什么ruby和jruby的begin-next-end的行为有所不同？

2 个答案: