mysqlダウンロードできない問題

➜  ~ sudo gem install mysql2 -v '0.3.21'
Password:
Building native extensions.  This could take a while...
ERROR:  Error installing mysql2:
	ERROR: Failed to build gem native extension.

    current directory: /Library/Ruby/Gems/2.3.0/gems/mysql2-0.3.21/ext/mysql2
/System/Library/Frameworks/Ruby.framework/Versions/2.3/usr/bin/ruby -r ./siteconf20180703-46977-151mij7.rb extconf.rb
checking for ruby/thread.h... yes
checking for rb_thread_call_without_gvl() in ruby/thread.h... yes
checking for rb_thread_blocking_region()... no
checking for rb_wait_for_single_fd()... yes
checking for rb_hash_dup()... yes
checking for rb_intern3()... yes
-----
Using mysql_config at /usr/local/bin/mysql_config
-----
checking for mysql.h... yes
checking for errmsg.h... yes
checking for mysqld_error.h... yes
-----
Setting rpath to /usr/local/Cellar/mysql/8.0.11/lib
-----
creating Makefile

To see why this extension failed to compile, please check the mkmf.log which can be found here:

  /Library/Ruby/Gems/2.3.0/extensions/universal-darwin-17/2.3.0/mysql2-0.3.21/mkmf.log

current directory: /Library/Ruby/Gems/2.3.0/gems/mysql2-0.3.21/ext/mysql2
make "DESTDIR=" clean

current directory: /Library/Ruby/Gems/2.3.0/gems/mysql2-0.3.21/ext/mysql2
make "DESTDIR="
compiling infile.c
compiling client.c
client.c:439:3: error: use of undeclared identifier 'my_bool'
  my_bool res = mysql_read_query_result(client);
  ^
client.c:441:19: error: use of undeclared identifier 'res'
  return (void *)(res == 0 ? Qtrue : Qfalse);
                  ^
client.c:762:3: error: use of undeclared identifier 'my_bool'
  my_bool boolval;
  ^
client.c:793:7: error: use of undeclared identifier 'boolval'
      boolval = (value == Qfalse ? 0 : 1);
      ^
client.c:794:17: error: use of undeclared identifier 'boolval'
      retval = &boolval;
                ^
client.c:797:10: error: use of undeclared identifier 'MYSQL_SECURE_AUTH'; did you mean 'MYSQL_DEFAULT_AUTH'?
    case MYSQL_SECURE_AUTH:
         ^~~~~~~~~~~~~~~~~
         MYSQL_DEFAULT_AUTH
/usr/local/Cellar/mysql/8.0.11/include/mysql/mysql.h:188:3: note: 'MYSQL_DEFAULT_AUTH' declared here
  MYSQL_DEFAULT_AUTH,
  ^
client.c:798:7: error: use of undeclared identifier 'boolval'
      boolval = (value == Qfalse ? 0 : 1);
      ^
client.c:799:17: error: use of undeclared identifier 'boolval'
      retval = &boolval;
                ^
client.c:830:38: error: use of undeclared identifier 'boolval'
        wrapper->reconnect_enabled = boolval;
                                     ^
client.c:1185:38: error: use of undeclared identifier 'MYSQL_SECURE_AUTH'; did you mean 'MYSQL_DEFAULT_AUTH'?
  return _mysql_client_options(self, MYSQL_SECURE_AUTH, value);
                                     ^~~~~~~~~~~~~~~~~
                                     MYSQL_DEFAULT_AUTH
/usr/local/Cellar/mysql/8.0.11/include/mysql/mysql.h:188:3: note: 'MYSQL_DEFAULT_AUTH' declared here
  MYSQL_DEFAULT_AUTH,
  ^
10 errors generated.
make: *** [client.o] Error 1

make failed, exit code 2

Gem files will remain installed in /Library/Ruby/Gems/2.3.0/gems/mysql2-0.3.21 for inspection.
Results logged to /Library/Ruby/Gems/2.3.0/extensions/universal-darwin-17/2.3.0/mysql2-0.3.21/gem_make.out```ここに言語を入力
コード