Revert "Merge pull request #19755 from yuki24/activerecord/support-for-set"

This reverts commit 524d40591eaa2f4d007409bfad386f6b107492eb, reversing
changes made to 34d3a6095100245283861ef480a54d0643bbee4c.

Reasoning behind the revert are in the PR discussion:
https://github.com/rails/rails/pull/19755

- This means that types can no longer cast to/from `Set`, and reasonably
  work with `where` (we already have this problem for `array`/`json`
  types on pg)
- This adds precedent for every other `Enumerable`, and we can't target
  `Enumerable` directly.
- Calling `to_a` on a `Set` is reasonable.

1 files changed, 0 insertions, 10 deletions

diff --git a/activerecord/test/cases/relations_test.rb b/activerecord/test/cases/relations_test.rb
index 7886d9e504..0cf44388fa 100644
--- a/activerecord/test/cases/relations_test.rb
+++ b/activerecord/test/cases/relations_test.rb
@@ -848,16 +848,6 @@ class RelationTest < ActiveRecord::TestCase
     }
   end
 
-  def test_find_all_using_where_with_a_set
-    david = authors(:david)
-    mary  = authors(:mary)
-    set   = Set.new([david.id, mary.id])
-
-    assert_queries(1) {
-      assert_equal [david, mary], Author.where(id: set).to_a
-    }
-  end
-
   def test_exists
     davids = Author.where(:name => 'David')
     assert davids.exists?