Make a deep copy of the _default_attributes in column_defaults

When column_defaults is called it calls `value` on each instance of
Attribute inside the _default_attributes set. Since value is memoized in
the Attribute instance and that Attribute instance is shared across all
instances of a model the next call to the default value will be memozied
not running the proc defined by the user.

Fixes #33031.

1 files changed, 14 insertions, 0 deletions

diff --git a/activerecord/test/cases/attributes_test.rb b/activerecord/test/cases/attributes_test.rb
index 3bc56694be..2632aec7ab 100644
--- a/activerecord/test/cases/attributes_test.rb
+++ b/activerecord/test/cases/attributes_test.rb
@@ -148,6 +148,20 @@ module ActiveRecord
       assert_equal 2, klass.new.counter
     end
 
+    test "procs for default values are evaluated even after column_defaults is called" do
+      klass = Class.new(OverloadedType) do
+        @@counter = 0
+        attribute :counter, :integer, default: -> { @@counter += 1 }
+      end
+
+      assert_equal 1, klass.new.counter
+
+      # column_defaults will increment the counter since the proc is called
+      klass.column_defaults
+
+      assert_equal 3, klass.new.counter
+    end
+
     test "procs are memoized before type casting" do
       klass = Class.new(OverloadedType) do
         @@counter = 0