Gem mysql2 adapter not installing - mysql

Question

When I try to install the mysql2 adapter gem, I get this error:
gem install mysql2 -v 0.3.21
Building native extensions. This could take a while...
ERROR: Error installing mysql2:
ERROR: Failed to build gem native extension.
/Users/jwan/.rbenv/versions/2.1.2/bin/ruby 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()... yes
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/8.0.12/lib
-----
creating Makefile
make "DESTDIR=" clean
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/8.0.12/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/8.0.12/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 /Users/jwan/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/mysql2-0.3.21 for inspection.
What does it mean and what is going on?
What does this line do: Setting rpath to /usr/local/Cellar/mysql/8.0.12/lib
Can I try pointing it to another version of mysql?

Answer 1

Because you're using an incomaptible version of the mysql2 gem for your rails version You have to make all the gem versions in your Gemfile a proper match One good way to do that is to google rubygems (gem name) versions and see it's runtime dependences and it's release date The release dates can be compared to the release dates of rails versions and other gems that it depends on When you're new it can take a little time