Install mysql2 gem on macOS Sierra

Question

I'm trying to install mysql2 gem (0.4.5) on macOS Sierra (10.12.1) and getting the error. I don't have local mysql server, it's remote.

Here is error log:

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 
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Using mysql_config at /usr/local/bin/mysql_config
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checking for mysql.h... yes
checking for errmsg.h... yes
checking for mysqld_error.h... yes
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Don't know how to set rpath on your system, if MySQL libraries are not    in path mysql2 may not load
-----
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Setting libpath to /usr/local/Cellar/mysql-connector-c/6.1.9/lib
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creating Makefile

To see why this extension failed to compile, please check the mkmf.log   which can be found here:
    /Users/user/.rbenv/versions/2.3.4/lib/ruby/gems/2.3.0/extensions/x86_64-darwin-16/2.3.0-static/mysql2-0.4.4/mkmf.log

current directory: /Users/user/.rbenv/versions/2.3.4/lib/ruby/gems/2.3.0/gems/mysql2-0.4.4/ext/mysql2
make "DESTDIR=" clean

current directory: /Users/user/.rbenv/versions/2.3.4/lib/ruby/gems/2.3.0/gems/mysql2-0.4.4/ext/mysql2
make "DESTDIR="
compiling client.c
compiling infile.c
compiling mysql2_ext.c
compiling result.c
compiling statement.c
linking shared-object mysql2/mysql2.bundle
ld: library not found for -l-lpthread
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [mysql2.bundle] Error 1

make failed, exit code 2

Did anyone meet similar error?

Answer 1

Fix:

Edit /usr/local/Cellar/mysql-connector-c/6.1.10/bin/mysql_config, find this line:

libs="$libs -l "

and change it to

libs="$libs -l mysqlclient "

---

Explanation:

-l-lpthread

The linker does not understand the option -l-lpthread. Two -l-l linker options are jammed up against each other. It is because the library name mysqlclientis missing from the generated make file.

I ran into this issue when trying to build the native extensions for the mysql2 gem on Ruby 2.4.1 using the mysql-connector-c from Home Brew

This was on MacOS 10.12.5.

The generated LIBS variable should look something this:

LIBS = $(LIBRUBYARG_SHARED) -L/usr/local/Cellar/mysql-connector-c/6.1.10/lib -l mysqlclient -lpthread -ldl -lobjc

It appears the variable is expanded from the file /usr/local/Cellar/mysql-connector-c/6.1.10/bin/mysql_config

The libs var in the file mysql_config should contain:

libs="$libs -l mysqlclient "

instead of

libs="$libs -l "

The var embedded_libs may be wrong too?

The mysql-connector-c lib installs and build fine via Home Brew it just appears the file mysql_config is incorrect or generated incorrectly.

Not sure the cause of the issue. Possibly Home Brew, mysql-connector-c, mysql2 gem build process, user environment?

Answer 2

The issue is that you're missing a library as the error message indicates

ld: library not found for -l-lpthread

EDIT: There seem to be other errors related that may be fixed with the instructions below, namely:

ld: library not found for -lssl

My guess is that you did not install xcode yet which happens to install a few more libraries. Please make sure to install xcode through the official app-store.

It might be necessary to re-install the command-line tools again as well (even if you had xcode installed and just updated it at some point).

xcode-select --install

Let me know if this helped!