Dates on gems—make this make sense

[zenspider]

10009 $ gem spec --ruby --remote minitest -v 5.0.0 | rg date
  s.date = "2013-05-10"
10010 $ gem spec --ruby --remote minitest -v 6.0.0 | rg date
  s.date = "1980-01-02"

How does this make any sense?

[hsbt]

This caused by #8568

If you don't specify Gem::Specification#date, it used the default value.

That behavior is confusing to users and maitainers. I also won't be able to find out when the latest version of a gem was released.

In my opinion, we should revert this behavior.

[zenspider]

I agree... I think it should be reverted as well.

insult to injury, the doco was never updated:

https://github.com/rubygems/rubygems/blob/master/lib/rubygems/specification.rb#L1678-L1679

[zenspider]

specification.rb also claims that the field is required, and yet has a lazy accessor. So much is bitrotted in this file.

[zenspider]

Also this warning to not set the date explicitly.

there's no meaning in this file.

[tenderlove]

I think the problem is that if you put the current date in the gem spec, you won't be able to do gem build on different days and end up with identical .gem files.

That behavior is confusing to users and maitainers. I also won't be able to find out when the latest version of a gem was released.

I don't think we can trust the date to understand when a gem was released. For example, I could do gem build, then wait a few days, and then push the gem to RubyGems.org. The date in the gem is unreliable.

IMO we should either remove the field (because it is currently useless), or make it so you can impact the date via environment variable.

[zenspider]

if the intent was to record the date it was built (vs released?), then it should be named as such. If I have a file on disk, I should be able to trust what it says. That seems reasonable to me. If someone wants to have a bunch of gems (or specs) on disk, then the values in those files should have some semantic value. I should be able to run gem spec --ruby on them and get meaningful data out of them.

1980-01-02 has zero semantic value... and before someone points at segiddons saying we should use the API to get this value, First, fuck no, Second:

10077 $ for V in 5 6 ; do for K in built_at created_at version_created_at ; do printf "%d.0.0 %20s = %s\n" $V $K $(gem api /api/v2/rubygems/minitest/versions/$V.0.0.json -j .$K) ; done; echo; done
5.0.0             built_at = "2013-05-10T00:00:00.000Z"
5.0.0           created_at = "2013-05-10T23:02:52.624Z"
5.0.0   version_created_at = "2013-05-10T23:02:52.624Z"

6.0.0             built_at = "1980-01-02T00:00:00.000Z" BULLSHIT
6.0.0           created_at = "2025-12-17T23:09:13.801Z"
6.0.0   version_created_at = "2025-12-17T23:09:13.801Z"

Until this change, offline rubygems were perfectly usable by themselves.

Also: things like ruby-toolbox aren't updating (in part) because gems being released aren't newer than the last recorded release.

[zenspider]

EVERYTHING about this is broken and making me angry:

10019 $ gem rebuild --diff minitest 6.0.0
Fetching minitest-6.0.0.gem
Downloaded minitest version 6.0.0 as /var/folders/9s/yqskfj712zgdhlmkb0jcq5_h0000gn/T/gem_rebuild20260212-50379-n1cx93/old/minitest-6.0.0.gem.
ERROR:  Couldn't find a gemspec file matching 'minitest' in /Users/ryan

10020 $ gem spec --ruby --remote minitest -v 6.0.0 > minitest.gemspec

10021 $ gem rebuild --diff minitest 6.0.0
Fetching minitest-6.0.0.gem
Downloaded minitest version 6.0.0 as /var/folders/9s/yqskfj712zgdhlmkb0jcq5_h0000gn/T/gem_rebuild20260212-50435-vuwsju/old/minitest-6.0.0.gem.
WARNING:  no files specified
WARNING:  See https://guides.rubygems.org/specification-reference/ for help
  Successfully built RubyGem
  Name: minitest
  Version: 6.0.0
  File: minitest-6.0.0.gem

Built at: 1980-01-01 16:00:00 PST (315619200)
Original build saved to:   /var/folders/9s/yqskfj712zgdhlmkb0jcq5_h0000gn/T/gem_rebuild20260212-50435-vuwsju/old/minitest-6.0.0.gem
Reproduced build saved to: /var/folders/9s/yqskfj712zgdhlmkb0jcq5_h0000gn/T/gem_rebuild20260212-50435-vuwsju/new/minitest-6.0.0.gem
Working directory: /Users/ryan

Hash comparison:
  4ca597fc1d735ea18d2b4b98c5fb1d5a6da4a6f35ddf32bd5fa3eded33a453be	/var/folders/9s/yqskfj712zgdhlmkb0jcq5_h0000gn/T/gem_rebuild20260212-50435-vuwsju/old/minitest-6.0.0.gem
  0beab0859fdc9193ffd3755bdc05201db843202a81a375c717decf959aa2032f	/var/folders/9s/yqskfj712zgdhlmkb0jcq5_h0000gn/T/gem_rebuild20260212-50435-vuwsju/new/minitest-6.0.0.gem

FAILURE - original and rebuild hashes did not match

Execution error: Failed to parse diffoscope output: unexpected character: 'Usage:' at line 1 column 1
Stderr: 

10022 $ diffoscope /var/folders/9s/yqskfj712zgdhlmkb0jcq5_h0000gn/T/gem_rebuild20260212-50093-s5f72x/{old,new}/minitest-6.0.0.gem
Execution error: Failed to parse diffoscope output: unexpected character: 'Usage:' at line 1 column 1
Stderr: 

[hsbt]

For example, I could do gem build, then wait a few days, and then push the gem to RubyGems.org. The date in the gem is unreliable.

Maked sense to me. I need to introduce to separate build date and publish date for gem.