I've been hung up on this issue for hours now and nothing I have found previously posted about this issue seems to work. Below is the mysql2 output for when I run bundle install:
Fetching mysql2 0.4.5
Installing mysql2 0.4.5 with native extensions
Gem::Ext::BuildError: ERROR: Failed to build gem native extension.
current directory: /Users/MYUSERNAME/Desktop/MY_PROJECT/vendor/ruby/2.4.0/gems/mysql2-0.4.5/ext/mysql2
/Users/MYUSERNAME/.rbenv/versions/2.4.2/bin/ruby -r ./siteconf20180623-40170-ndn6t0.rb extconf.rb --with-mysql-config=/usr/local/Cellar/mysql/8.0.11/bin/mysql_config
checking for rb_absint_size()... yes
checking for rb_absint_singlebit_p()... yes
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
checking for rb_big_cmp()... yes
-----
Using mysql_config at /usr/local/Cellar/mysql/8.0.11/bin/mysql_config
-----
checking for mysql.h... yes
checking for SSL_MODE_DISABLED in mysql.h... yes
checking for SSL_MODE_PREFERRED in mysql.h... yes
checking for SSL_MODE_REQUIRED in mysql.h... yes
checking for SSL_MODE_VERIFY_CA in mysql.h... yes
checking for SSL_MODE_VERIFY_IDENTITY in 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
current directory: /Users/MYUSERNAME/Desktop/MY_PROJECT/vendor/ruby/2.4.0/gems/mysql2-0.4.5/ext/mysql2
make "DESTDIR=" clean
current directory: /Users/MYUSERNAME/Desktop/MY_PROJECT/vendor/ruby/2.4.0/gems/mysql2-0.4.5/ext/mysql2
make "DESTDIR="
compiling client.c
In file included from client.c:1:
In file included from ./mysql2_ext.h:41:
./result.h:24:3: error: unknown type name 'my_bool'
my_bool *is_null;
^
./result.h:25:3: error: unknown type name 'my_bool'
my_bool *error;
^
client.c:507:3: error: use of undeclared identifier 'my_bool'
my_bool res = mysql_read_query_result(client);
^
client.c:509:19: error: use of undeclared identifier 'res'
return (void *)(res == 0 ? Qtrue : Qfalse);
^
client.c:828:3: error: use of undeclared identifier 'my_bool'
my_bool boolval;
^
client.c:859:7: error: use of undeclared identifier 'boolval'
boolval = (value == Qfalse ? 0 : 1);
^
client.c:860:17: error: use of undeclared identifier 'boolval'
retval = &boolval;
^
client.c:863:10: 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:864:7: error: use of undeclared identifier 'boolval'
boolval = (value == Qfalse ? 0 : 1);
^
client.c:865:17: error: use of undeclared identifier 'boolval'
retval = &boolval;
^
client.c:896:38: error: use of undeclared identifier 'boolval'
wrapper->reconnect_enabled = boolval;
^
client.c:1285:38: 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,
^
12 errors generated.
make: *** [client.o] Error 1
make failed, exit code 2
Gem files will remain installed in /Users/MYUSERNAME/Desktop/MY_PROJECT/vendor/ruby/2.4.0/gems/mysql2-0.4.5 for inspection.
Results logged to /Users/MYUSERNAME/Desktop/MY_PROJECT/vendor/ruby/2.4.0/extensions/x86_64-darwin-17/2.4.0-static/mysql2-0.4.5/gem_make.out
An error occurred while installing mysql2 (0.4.5), and Bundler cannot continue.
Make sure that `gem install mysql2 -v '0.4.5'` succeeds before bundling.
In Gemfile:
mysql2
This is the relevant portion of my Gemfile:
gem 'rails', '5.1.4'
gem 'mysql2', '0.4.5'
I'm running MacOS High Sierra and have MySQL installed via Homebrew. I've tried running as bundle install --system, adding /tmp/mysql.sock to my database.yml (it was already there), as well as reinstalling just about every relevant dev tool on my system, all with no luck.
Its also worth noting that I've done this in the past with no issues... I'm not really sure what changed, but it seems to only be a problem on my system.
Thanks for any help you can provide
UPDATE: I'm able to the the gem for mysql2 v0.4.5 to install properly when I run gem install mysql2 -v '0.4.5' -- --srcdir=/usr/local/Cellar/mysql/8.0.11/include/
So the problem ended up being that homebrew recently made mysql v8.x.x the standard installation and I ran homebrew upgrades which took me off the standard that our codebase supported... Noted for the future. Once I brought my system mysql version down to accurately reflect what mysql2 was looking for, it worked.
来源：https://stackoverflow.com/questions/51002359/mysql2-failing-bundle-install