From: "jeremyevans0 (Jeremy Evans) via ruby-core" <ruby-core@...>
Date: 2025-10-30T16:36:34+00:00
Subject: [ruby-core:123617] [Ruby Bug#21654] Set#new calls extra methods compared to previous versions

Issue #21654 has been updated by jeremyevans0 (Jeremy Evans).


tenderlovemaking (Aaron Patterson) wrote in #note-10:
> mame (Yusuke Endoh) wrote in #note-9:
> > Dan0042 (Daniel DeLorme) wrote in #note-7:
> > > What that really what you meant by "checking if Range#end is nil is good enough" ?
> > 
> > Yes. The original issue (#21513) was about the consistency between `(1..).to_a` and `(1..).to_set`. Since `(1..1/0.0).to_a` hangs, I think it's fine if `(1..1/0.0).to_set` also hangs.
> > 
> > Admittedly, I'm biased: I generally feel that proactively raising exceptions for endless range operations is unnecessary. If an operation hangs, let it hang.
> 
> I personally agree with this.  If I write an infinite loop, I expect it to loop infinitely, even if I wrote the infinite loop by mistake.  Calling `to_a` or `to_set` on an infinite range is iterating infinitely.

I agree with @mame and @tenderlovemaking. Removing special handling of infinite ranges avoids the original issue  (calling `size`), as well as avoiding the `nil` vs `Infinity` range end issue. I think we should just revert commit:d4020dd5faf28486123853e7f00c36139fc07793.

----------------------------------------
Bug #21654: Set#new calls extra methods compared to previous versions
https://bugs.ruby-lang.org/issues/21654#change-115003

* Author: tenderlovemaking (Aaron Patterson)
* Status: Open
* ruby -v: ruby 3.5.0dev (2025-10-24T15:50:47Z master a9f24aaccb) +PRISM [arm64-darwin25]
* Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN
----------------------------------------
I'm trying to test Ruby 3.5.0 with our Rails application and we've found that `Set.new` is now causing extra database queries to happen.

The changes in d4020dd5faf call "size" on enumerable objects that are passed to the `new` method, and this causes extra "COUNT" queries to happen with ActiveRecord associations.

For example:

```ruby
Set.new(some_activerecord_association)
```

Previously, the above code would only do one query by iterating over the association. Now it issues two queries, a count query, and then the normal query for results.

Since d4020dd5faf is dealing with endless ranges, I would like to narrow the scope from all Enumerable objects to just Ranges.  Unfortunately, I noticed we have a test like this:

```ruby
    assert_raise(ArgumentError) {
      Set.new(1.upto(Float::INFINITY))
    }
```

I'm not sure how we can handle such a case without testing `size`.



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