Merge pull request #20645 from kamipo/fix_mysql_set_type_bug

Fix undesired type lookup with `SET` in MySQL

activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb

@@ -814,7 +814,6 @@ def initialize_type_map(m) # :nodoc:
         register_integer_type m, %r(^tinyint)i,   limit: 1
 
         m.alias_type %r(tinyint\(1\))i,  'boolean' if emulate_booleans
-        m.alias_type %r(set)i,           'varchar'
         m.alias_type %r(year)i,          'integer'
         m.alias_type %r(bit)i,           'binary'
 
@@ -823,6 +822,12 @@ def initialize_type_map(m) # :nodoc:
             .split(',').map{|enum| enum.strip.length - 2}.max
           MysqlString.new(limit: limit)
         end
+
+        m.register_type(%r(^set)i) do |sql_type|
+          limit = sql_type[/^set\((.+)\)/i, 1]
+            .split(',').map{|set| set.strip.length - 1}.sum - 1
+          MysqlString.new(limit: limit)
+        end
       end
 
       def register_integer_type(mapping, key, options) # :nodoc:

activerecord/test/cases/connection_adapters/mysql_type_lookup_test.rb

@@ -22,6 +22,10 @@ def test_string_types
         assert_lookup_type :string, "SET('one', 'two', 'three')"
       end
 
+      def test_set_type_with_value_matching_other_type
+        assert_lookup_type :string, "SET('unicode', '8bit', 'none', 'time')"
+      end
+
       def test_enum_type_with_value_matching_other_type
         assert_lookup_type :string, "ENUM('unicode', '8bit', 'none')"
       end