Enumerator::Lazy is missing a few methods, leading to different behavior from MRI #2273
Description
Hello there 👋
I was trying out the ddtrace gem specs with TruffleRuby, and ran into a failure in chunker_spec.rb.
This is caused by TruffleRuby not implementing the full set of methods on Enumerator::Lazy, which means that a few of the method implementations from Enumerable get used instead, which leads to lazy enumerables becoming non-lazy accidentally.
The specific example I ran into is the case of slice_before. Here's how it behaves on MRI:
[20] pry(main)> puts RUBY_DESCRIPTION
ruby 2.7.2p137 (2020-10-01 revision 5445e04352) [x86_64-darwin19]
=> nil
[21] pry(main)> [1, 2, 3].lazy.slice_before { |n| n > 2 }
=> #<Enumerator::Lazy: ...>
and here's how it behaves on TruffleRuby:
[16] pry(main)> puts RUBY_DESCRIPTION
truffleruby 21.0.0.2, like ruby 2.7.2, GraalVM CE Native [x86_64-darwin]
=> nil
[17] pry(main)> [1, 2, 3].lazy.slice_before { |n| n > 2 }
=> #<Enumerator: #<Enumerator::Generator:0x2618 @proc=#<Proc:0x2628 <internal:core> core/enumerable.rb:229>>:each>
Looking at the list of methods that Enumerator::Lazy has on MRI vs on TruffleRuby, it looks like this issue would apply to a few more:
[24] pry(main)> puts RUBY_DESCRIPTION
ruby 2.7.2p137 (2020-10-01 revision 5445e04352) [x86_64-darwin19]
=> nil
[25] pry(main)> example = [].lazy
=> #<Enumerator::Lazy: ...>
[26] pry(main)> ls example
Enumerable#methods:
all? cycle each_slice first max min_by one? sort to_a
any? detect entries group_by max_by minmax partition sort_by to_h
chain each_cons find include? member? minmax_by reduce sum to_set
count each_entry find_index inject min none? reverse_each tally
Enumerator#methods:
+ each_with_index feed next peek rewind with_object
each each_with_object inspect next_values peek_values size
Enumerator::Lazy#methods:
chunk drop filter force map slice_before to_enum
chunk_while drop_while filter_map grep reject slice_when uniq
collect eager find_all grep_v select take with_index
collect_concat enum_for flat_map lazy slice_after take_while zipvs TruffleRuby:
[18] pry(main)> puts RUBY_DESCRIPTION
truffleruby 21.0.0.2, like ruby 2.7.2, GraalVM CE Native [x86_64-darwin]
=> nil
[19] pry(main)> example = [].lazy
=> #<Enumerator::Lazy: #<Enumerator::Generator:0x26f8 @proc=#<Proc:0x2708 <internal:core> core/enumerator.rb:285>>:each>
[20] pry(main)> ls example
Enumerable#methods:
all? cycle entries force max_by minmax_by reverse_each sort_by to_set
any? detect filter_map group_by member? none? slice_after sum
chain each_cons find include? min one? slice_before tally
chunk_while each_entry find_index inject min_by partition slice_when to_a
count each_slice first max minmax reduce sort to_h
Enumerator#methods:
+ each_with_index feed next peek rewind with_index
each each_with_object inspect next_values peek_values size with_object
Enumerator::Lazy#methods:
chunk drop enum_for flat_map lazy select to_enum
collect drop_while filter grep map take uniq
collect_concat eager find_all grep_v reject take_while zipLet me know if I can provide any more information! :)