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Bug #18971

Updated by Voileexperiments (Library Voile) over 2 years ago

These results with lazy enumerators are as expected: 

 ``` ruby 
 (2..10).take(0).to_a # => [] 
 (2..10).take(0).map(:&itself).to_a # => [] 
 (2..10).lazy.take(0).to_a # => [] 
 ``` 

 However, once another operation is added after `take(0)`, if first element will pass through directly it will leak through: 

 ``` ruby 
 (2..10).lazy.take(0).map(&:itself).to_a # => [2] 
 (2..10).lazy.take(0).select(&:even?).to_a # => [2] 
 (2..10).lazy.take(0).select(&:odd?).to_a # => [] 
 (2..10).lazy.take(0).reject(&:even?).to_a # => [] 
 (2..10).lazy.take(0).reject(&:odd?).to_a # => [2] 
 (2..10).lazy.take(0).take(1).to_a # => [2] 
 (2..10).lazy.take(0).take(0).take(1).to_a # => [2] 
 (2..10).lazy.take(0).drop(0).to_a # => [2] 
 (2..10).lazy.take(0).find_all {|_| true}.to_a # => [2] 
 (2..10).lazy.take(0).zip((12..20)).to_a # => [[2, 12]] 
 (2..10).lazy.take(0).uniq.to_a # => [2] 
 (2..10).lazy.take(0).sort.to_a # => [] 
 (2..2).lazy.take(0).sort.to_a # => [] 
 ``` 

 Non lazy versions all return `[]` as expected. 

 In 3.1.0 All of them behave as expected as well: 

 ``` ruby 
 (2..10).lazy.take(0).map(&:itself).to_a # => [] 
 (2..10).lazy.take(0).select(&:even?).to_a # => [] 
 (2..10).lazy.take(0).select(&:odd?).to_a # => [] 
 (2..10).lazy.take(0).reject(&:even?).to_a # => [] 
 (2..10).lazy.take(0).reject(&:odd?).to_a # => [] 
 (2..10).lazy.take(0).take(1).to_a # => [] 
 (2..10).lazy.take(0).take(0).take(1).to_a # => [] 
 (2..10).lazy.take(0).drop(0).to_a # => [] 
 (2..10).lazy.take(0).find_all {|_| true}.to_a # => [] 
 (2..10).lazy.take(0).zip((12..20)).to_a # => [] 
 (2..10).lazy.take(0).uniq.to_a # => [] 
 (2..10).lazy.take(0).sort.to_a # => [] 
 (2..2).lazy.take(0).sort.to_a # => [] 
 ```

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