我尝试捆绑应用程序时出现此错误的任何原因：我尝试按照他们的建议安装gem install mysql2 -v'0.3.21'，但无法正确安装。我也在macOS High Sierra上运行它。对不起，我对此问题措辞不好，因为这是我第一次与红宝石合作。
To see why this extension failed to compile, please check the mkmf.log which can be found here:
/Users/yamanshrestha/Desktop/Dorsata/vendor/bundle/ruby/2.3.0/extensions/universal-darwin-17/2.3.0/mysql2-0.3.21/mkmf.log
current directory: /Users/yamanshrestha/Desktop/Dorsata/vendor/bundle/ruby/2.3.0/gems/mysql2-0.3.21/ext/mysql2
make "DESTDIR=" clean
current directory: /Users/yamanshrestha/Desktop/Dorsata/vendor/bundle/ruby/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: …