Bug #21828: An incorrect warning message related to `benchmark` is shown when using `benchmark-ips`

• Status: Closed
• Assignee: hsbt (Hiroshi SHIBATA)
• Target version: -
• ruby -v: ruby 4.0.1 (2026-01-13 revision e04267a14b) +PRISM [x86_64-linux]
• Backport: 3.2: DONTNEED, 3.3: DONTNEED, 3.4: DONTNEED, 4.0: DONE

[y-yagi (Yuji Yaginuma)]

Descrition

When using benchmark-ips gem with Ruby 4.0.0, the warning related to benchmark gem is shown.

Step to reproduce

# Gemfile
# frozen_string_literal: true

source "https://rubygems.org"

gem "benchmark-ips"

# script.rb
require "benchmark/ips"

$ bundle exec ruby -v script.rb
ruby 4.0.0 (2025-12-25 revision 553f1675f3) +PRISM [x86_64-linux]
script.rb:1: warning: benchmark/ips is found in benchmark, which is not part of the default gems since Ruby 4.0.0.
You can add benchmark to your Gemfile or gemspec to fix this error.

Expected behavior

The warning for benchmark isn't shown when using benchmark-ips.

[hsbt (Hiroshi SHIBATA)]

• Status changed from Open to Assigned
• Assignee set to hsbt (Hiroshi SHIBATA)

[khasinski (Chris Hasiński)]

• Status changed from Assigned to Closed

Applied in changeset git|768862868472fb1800e556effb0e37be2fbaec52.

---

Fix incorrect bundled gems warning for hyphenated gem names

When requiring a file like "benchmark/ips", the warning system would
incorrectly warn about the "benchmark" gem not being a default gem,
even when the user has "benchmark-ips" (a separate third-party gem)
in their Gemfile.

The fix checks if a hyphenated version of the require path exists in
the bundle specs before issuing a warning. For example, requiring
"benchmark/ips" now checks for both "benchmark" and "benchmark-ips"
in the Gemfile.

[Bug #21828]

[hsbt (Hiroshi SHIBATA)]

• Backport changed from 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN, 4.0: UNKNOWN to 3.2: DONTNEED, 3.3: DONTNEED, 3.4: DONTNEED, 4.0: REQUIRED

https://github.com/ruby/ruby/pull/15824

[k0kubun (Takashi Kokubun)]

• Backport changed from 3.2: DONTNEED, 3.3: DONTNEED, 3.4: DONTNEED, 4.0: REQUIRED to 3.2: DONTNEED, 3.3: DONTNEED, 3.4: DONTNEED, 4.0: DONE

ruby_4_0 8d764da35768073c2e21ffeffa27ff2f3ab589b0.

[y-yagi (Yuji Yaginuma)]

• ruby -v changed from ruby 4.0.0 (2025-12-25 revision 553f1675f3) +PRISM [x86_64-linux] to ruby 4.0.1 (2026-01-13 revision e04267a14b) +PRISM [x86_64-linux]

Thanks for the fix, but I still get the same warning on Ruby 4.0.1.

$ bundle exec ruby -v script.rb
ruby 4.0.1 (2026-01-13 revision e04267a14b) +PRISM [x86_64-linux]
/home/y-yagi/.rbenv/versions/4.0.1/lib/ruby/gems/4.0.0/gems/benchmark-ips-2.14.0/lib/benchmark/ips.rb:2: warning: benchmark/timing is found in benchmark, which is not part of the default gems since Ruby 4.0.0.
You can add benchmark to your Gemfile or gemspec to fix this error.

[Eregon (Benoit Daloze)]

• Status changed from Closed to Open

Re-opening since it's still a problem on master and on 4.0.1, so the fix doesn't seem to work.
Another reproduction from https://github.com/evanphx/benchmark-ips/pull/148 is:

git clone [e-mail]:evanphx/benchmark-ips.git
cd benchmark-ips
bundle
bundle exec rake

which gives:

/home/eregon/code/benchmark-ips/test/test_benchmark_ips.rb:2: warning: benchmark/ips is found in benchmark, which is not part of the default gems since Ruby 4.0.0.
You can add benchmark to your Gemfile or gemspec to fix this error.
...

[hsbt (Hiroshi SHIBATA)]

• Status changed from Open to Closed

The additional changes has been merged. I believe they fixed that.

• https://github.com/ruby/ruby/pull/15908
• https://github.com/ruby/ruby/pull/16154

Please look the merged commit at stable branch at first.

[Eregon (Benoit Daloze)]

• Status changed from Closed to Open

As I said:

Eregon (Benoit Daloze) wrote in #note-6:

still a problem on master

I have tried with ruby 4.1.0dev (2026-03-11T07:46:22Z master c08f977ac7) +PRISM [x86_64-linux] specifically.

Please try the reproduction before closing.

[Eregon (Benoit Daloze)]

Also happens on 4.0-dev from ruby-build (ruby 4.0.1 (2026-03-10 revision 21f2bbf322) +PRISM [x86_64-linux]).

[Eregon (Benoit Daloze)]

Interestingly it seems fixed for the original reproduction in the issue description, but not for the new reproduction of running benchmark-ips's tests.

[Eregon (Benoit Daloze)]

A main difference between both reproductions are the Gemfile.lock, for the reproduction in the issue description:

GEM
  remote: https://rubygems.org/
  specs:
    benchmark-ips (2.14.0)

PLATFORMS
  ruby
  x86_64-linux

DEPENDENCIES
  benchmark-ips

CHECKSUMS
  benchmark-ips (2.14.0) sha256=b72bc8a65d525d5906f8cd94270dccf73452ee3257a32b89fbd6684d3e8a9b1d

BUNDLED WITH
  4.1.0.dev

and for the reproduction from https://bugs.ruby-lang.org/issues/21828#note-6:

GEM
  remote: https://rubygems.org/
  specs:
    drb (2.2.3)
    minitest (6.0.2)
      drb (~> 2.0)
      prism (~> 1.5)
    prism (1.9.0)
    rake (13.3.1)

PLATFORMS
  ruby
  x86_64-linux

DEPENDENCIES
  minitest
  rake (>= 10.5)

CHECKSUMS
  drb (2.2.3) sha256=0b00d6fdb50995fe4a45dea13663493c841112e4068656854646f418fda13373
  minitest (6.0.2) sha256=db6e57956f6ecc6134683b4c87467d6dd792323c7f0eea7b93f66bd284adbc3d
  prism (1.9.0) sha256=7b530c6a9f92c24300014919c9dcbc055bf4cdf51ec30aed099b06cd6674ef85
  rake (13.3.1) sha256=8c9e89d09f66a26a01264e7e3480ec0607f0c497a861ef16063604b1b08eb19c

BUNDLED WITH
  4.0.3

So it seems like the fix only works when there is a dependency on the benchmark-ips gem, but there could be benchmark/something files outside a gem and then it still warns incorrectly.

[hsbt (Hiroshi SHIBATA)]

• Status changed from Open to Closed

Applied in changeset git|679e4069217104f4fe1d887ec48aa8c3537245b2.

---

Suppress bundled gems warning for subfeatures found outside stdlib [Bug #21828]

Co-Authored-By: Claude Opus 4.6 [e-mail]

[Eregon (Benoit Daloze)]

Thank you for the quick fix!