Deprecate the validate: false option for check_constraint

`check_constraint` with `validate: false` option actually creates a valid check constraint
because PostgreSQL ignores `NOT VALID` option used with `CREATE TABLE`
statement.

To create a check constraint that is `NOT VALID`, `add_check_constraint`
is preferred that generates `ALTER  TABLE` statement with `NOT VALID` option.

- `check_constraint` with `validate: false` option creates a valid check constraint

```ruby
create_table :posts, force: true do |t|
  t.check_constraint "id > 0", name: "foo", validate: false
end
```

```sql
CREATE TABLE "posts" ("id" bigserial primary key, CONSTRAINT foo CHECK (id > 0) NOT VALID);
SELECT conname, convalidated FROM pg_constraint WHERE contype = 'c' AND conname = 'foo';

/*
 conname | convalidated
---------+--------------
 foo     | t
(1 row)
*/
```

- `add_check_constraint` with `validate: false` option creates a invalid check constraint

```ruby
create_table :posts, force: true do |t|
end
add_check_constraint :posts, "id > 0", name: "foo", validate: false
```

```sql
CREATE TABLE "posts" ("id" bigserial primary key);
ALTER TABLE "posts" ADD CONSTRAINT foo CHECK (id > 0) NOT VALID;
SELECT conname, convalidated FROM pg_constraint WHERE contype = 'c' AND conname = 'foo';
/*
 conname | convalidated
---------+--------------
 foo     | f
(1 row)
*/
```

Related to rails#53732

Refer to the following discussion at pgsql-hackers mailing list.
https://www.postgresql.org/message-id/202412050936.bse4z5tbmze6%40alvherre.pgsql

> Maybe it would have been wise to forbid NOT VALID when used with CREATE
> TABLE.  But we didn't.  Should we do that now?  Maybe we can just
> document that you can specify it but it doesn't do anything.

activerecord/CHANGELOG.md

@@ -1,3 +1,10 @@
+*   Deprecate the `validate: false` option for `check_constraint`.
+
+    PostgreSQL ignores the `NOT VALID` option for check constraints within a `CREATE TABLE` statement.
+    To enable the `NOT VALID` option, use `add_check_constraint` which generates an `ALTER TABLE` statement.
+
+    *Yasuo Honda*
+
 *   Change the payload name of `sql.active_record` notification for eager
     loading from "SQL" to "#{model.name} Eager Load".
 

activerecord/lib/active_record/connection_adapters/postgresql/schema_definitions.rb

@@ -261,6 +261,17 @@ def unique_constraint(column_name, **options)
           unique_constraints << new_unique_constraint_definition(column_name, options)
         end
 
+        def check_constraint(expression, **options)
+          if options[:validate] == false
+            ActiveRecord.deprecator.warn(<<~MSG)
+              Providing `validate: false` for `check_constraint` is deprecated because it is ignored by the PostgreSQL.
+              Use the `add_check_constraint` with `validate: false` to create a check constraint that is `NOT VALID`.
+            MSG
+          end
+
+          super
+        end
+
         def new_exclusion_constraint_definition(expression, options) # :nodoc:
           options = @conn.exclusion_constraint_options(name, expression, options)
           ExclusionConstraintDefinition.new(name, expression, options)

activerecord/lib/active_record/migration/compatibility.rb

@@ -32,6 +32,22 @@ def self.find(version)
       V8_1 = Current
 
       class V8_0 < V8_1
+        if connection.adapter_name == "PostgreSQL"
+          module TableDefinition
+            def check_constraint(expression, **options)
+              options.delete(:validate)
+              super
+            end
+          end
+        end
+
+        private
+          def compatible_table_definition(t)
+            class << t
+              prepend TableDefinition
+            end
+            super
+          end
       end
 
       class V7_2 < V8_0

activerecord/test/cases/migration/check_constraint_test.rb

@@ -206,6 +206,18 @@ def test_schema_dumping_with_validate_true
 
             assert_match %r{\s+t.check_constraint "quantity > 0", name: "quantity_check"$}, output
           end
+
+          def test_not_valid_check_constraint_in_create_table
+            assert_deprecated(ActiveRecord.deprecator) do
+              @connection.create_table :nonvalid_constraints, id: false, force: true do |t|
+                t.string :name
+                t.check_constraint "char_length(name) >= 5", name: "name_const", validate: false
+              end
+            ensure
+              @connection.drop_table(:nonvalid_constraints, if_exists: true)
+              ActiveRecord::Base.clear_cache!
+            end
+          end
         else
           # Check constraint should still be created, but should not be invalid
           def test_add_invalid_check_constraint

activerecord/test/cases/migration/compatibility_test.rb

@@ -648,6 +648,26 @@ def migrate(x)
           connection.drop_table(:sub_testings, if_exists: true)
           ActiveRecord::Base.clear_cache!
         end
+
+        def test_check_constraint_with_validate_false
+          migration = Class.new(ActiveRecord::Migration[8.0]) do
+            def migrate(x)
+              create_table :check_constraint_testings, force: true do |t|
+                t.string :name
+
+                t.timestamps
+                t.check_constraint "char_length(name) >= 5", name: "name_const", validate: false
+              end
+            end
+          end.new
+
+          assert_not_deprecated(ActiveRecord.deprecator) do
+            ActiveRecord::Migrator.new(:up, [migration], @schema_migration, @internal_metadata).migrate
+          end
+        ensure
+          connection.drop_table(:check_constraint_testings, if_exists: true)
+          ActiveRecord::Base.clear_cache!
+        end
       end
 
       if current_adapter?(:Mysql2Adapter, :TrilogyAdapter)