Bug #17789: Incompatible behavior of Enumarator::Lazy#with_index

• Status: Closed
• Assignee: -
• Target version: -
• ruby -v: ruby 3.0.1p64 (2021-04-05 revision 0fb782ee38) [x86_64-darwin20]
• Backport: 2.6: UNKNOWN, 2.7: UNKNOWN, 3.0: UNKNOWN

[soudai_s (Soudai Sasada)]

this method ignores the block passed to it, but this behavior looks different from the Enumerator (super class).

$ ruby -e '%w(a).lazy.with_index { |s, i| puts "#{s} => #{i}" }'
a => 0 # Expected, but doesn't actually print anything

After confirmation I found #16414 but this behavior was not fixed and the doc in the modified source code states: "If a block given, iterates the given block for each element".
Is this behavior intended?

[zverok (Victor Shepelev)]

It doesn't ignores the block. It is just lazy to perform it :)

%w(a).lazy.with_index { |s, i| puts "#{s} => #{i}" }
# => #<Enumerator::Lazy: ...>

%w(a).lazy.with_index { |s, i| puts "#{s} => #{i}" }.force
# a => 0

[soudai_s (Soudai Sasada)]

It means it's no longer compatible with 2.6 or under, isn't it?
Thank you for quick reply!

[jeremyevans0 (Jeremy Evans)]

• Status changed from Open to Closed

This is expected. The behavior has changed. All bug fixes are incompatibilities.