Refactor around sql_type metadata and column

* remove useless `@type_metadata` and `@array`
* move the compatibility code (for array) into column
* etc.

activerecord/lib/active_record/connection_adapters/mysql/type_metadata.rb

@@ -10,12 +10,11 @@ class TypeMetadata < DelegateClass(SqlTypeMetadata) # :nodoc:
 
         def initialize(type_metadata, extra: "")
           super(type_metadata)
-          @type_metadata = type_metadata
           @extra = extra
         end
 
         def ==(other)
-          other.is_a?(MySQL::TypeMetadata) &&
+          other.is_a?(TypeMetadata) &&
             __getobj__ == other.__getobj__ &&
             extra == other.extra
         end

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

@@ -4,8 +4,7 @@ module ActiveRecord
   module ConnectionAdapters
     module PostgreSQL
       class Column < ConnectionAdapters::Column # :nodoc:
-        delegate :array, :oid, :fmod, to: :sql_type_metadata
-        alias :array? :array
+        delegate :oid, :fmod, to: :sql_type_metadata
 
         def initialize(*, serial: nil, **)
           super
@@ -15,6 +14,15 @@ def initialize(*, serial: nil, **)
         def serial?
           @serial
         end
+
+        def array
+          sql_type_metadata.sql_type.end_with?("[]")
+        end
+        alias :array? :array
+
+        def sql_type
+          super.sub(/\[\]\z/, "")
+        end
       end
     end
     PostgreSQLColumn = PostgreSQL::Column # :nodoc:

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

@@ -675,7 +675,7 @@ def fetch_type_metadata(column_name, sql_type, oid, fmod)
               precision: cast_type.precision,
               scale: cast_type.scale,
             )
-            PostgreSQLTypeMetadata.new(simple_type, oid: oid, fmod: fmod)
+            PostgreSQL::TypeMetadata.new(simple_type, oid: oid, fmod: fmod)
           end
 
           def sequence_name_from_parts(table_name, column_name, suffix)

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

@@ -3,39 +3,34 @@
 module ActiveRecord
   # :stopdoc:
   module ConnectionAdapters
-    class PostgreSQLTypeMetadata < DelegateClass(SqlTypeMetadata)
-      undef to_yaml if method_defined?(:to_yaml)
+    module PostgreSQL
+      class TypeMetadata < DelegateClass(SqlTypeMetadata)
+        undef to_yaml if method_defined?(:to_yaml)
 
-      attr_reader :oid, :fmod, :array
+        attr_reader :oid, :fmod
 
-      def initialize(type_metadata, oid: nil, fmod: nil)
-        super(type_metadata)
-        @type_metadata = type_metadata
-        @oid = oid
-        @fmod = fmod
-        @array = /\[\]$/.match?(type_metadata.sql_type)
-      end
-
-      def sql_type
-        super.gsub(/\[\]$/, "")
-      end
+        def initialize(type_metadata, oid: nil, fmod: nil)
+          super(type_metadata)
+          @oid = oid
+          @fmod = fmod
+        end
 
-      def ==(other)
-        other.is_a?(PostgreSQLTypeMetadata) &&
-          __getobj__ == other.__getobj__ &&
-          oid == other.oid &&
-          fmod == other.fmod &&
-          array == other.array
-      end
-      alias eql? ==
+        def ==(other)
+          other.is_a?(TypeMetadata) &&
+            __getobj__ == other.__getobj__ &&
+            oid == other.oid &&
+            fmod == other.fmod
+        end
+        alias eql? ==
 
-      def hash
-        PostgreSQLTypeMetadata.hash ^
-          __getobj__.hash ^
-          oid.hash ^
-          fmod.hash ^
-          array.hash
+        def hash
+          TypeMetadata.hash ^
+            __getobj__.hash ^
+            oid.hash ^
+            fmod.hash
+        end
       end
     end
+    PostgreSQLTypeMetadata = PostgreSQL::TypeMetadata
   end
 end