Bug #21001: unexpected nil result from proc with ensure and next

• Status: Closed
• Assignee: prism
• Target version: -
• ruby -v: ruby 3.4.1 (2024-12-25 revision 48d4efcb85) +PRISM [x86_64-linux]
• Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: REQUIRED

[aharpervc (Andrew Harper)]

Hello,

I have noticed a different program behavior in Ruby 3.4 compared to previous versions. This is a simplified example for debugging that returns the expected result in Ruby 3.3 but nil in Ruby 3.4

Here is the example program:

puts "Ruby: #{RUBY_VERSION}"

# okay all versions
# RUN_ARRAY = [1]

# fails ruby 3.4 only
RUN_ARRAY = [1,2]

MAP_PROC = Proc.new do |&blk|
  block_results = []
  RUN_ARRAY.each do |value|
    block_value = blk.call(value)
    block_results.push block_value
  end
  block_results
ensure
  next block_results
end

test_fn_results = MAP_PROC.call do |value|
  break if value > 1
  next value
end

puts test_fn_results.inspect

For Ruby 3.3.6 the output is:

Ruby: 3.3.6
[1]

For Ruby 3.4.1 the output is:

Ruby: 3.4.1
nil

I am expecting the Ruby 3.3 output even for Ruby 3.4. This appears to be a bug, since the program implementation is unchanged. Perhaps there is a bug in the code that is now only showing up with Ruby 3.4, but that seemed unlikely since it's working as expected in other versions.

Thank you

[ydah (Yudai Takada)]

memo) This does not occur even in Ruby 3.4.1 when --parser=parse.y.

❯ ruby --parser=parse.y -e 'puts "Ruby: #{RUBY_VERSION}"

# okay all versions
# RUN_ARRAY = [1]

# fails ruby 3.4 only
RUN_ARRAY = [1,2]

MAP_PROC = Proc.new do |&blk|
  block_results = []
  RUN_ARRAY.each do |value|
    block_value = blk.call(value)
    block_results.push block_value
  end
  block_results
ensure
  next block_results
end

test_fn_results = MAP_PROC.call do |value|
  break if value > 1
  next value
end

puts test_fn_results.inspect'
Ruby: 3.4.1
[1]

[kddnewton (Kevin Newton)]

• Assignee set to prism

[kddnewton (Kevin Newton)]

• Status changed from Open to Closed

Applied in changeset git|31905d9e23ec6d1fa2a52f1ef2533f2056e7c9fb.

---

Allow escaping from ensures through next

Fixes [Bug #21001]

[alanwu (Alan Wu)]

• Backport changed from 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN to 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: REQUIRED