ruby - gem mysql2在ruby1.9.3上安装报错

Question

刚刚更新到 macOS Mojave，通过 brew 重新安装了 mysql 并下载了最新的 xcode 9.2。在尝试为旧的 Rails 项目设置开发环境时， bundle 在安装 mysql2 gem 时崩溃。一开始我以为是因为最新的 mysql2 版本与 ruby​​ 1.9 不兼容，所以我尝试了:

gem install mysql2 -v '0.3.17'

我收到了:

/Users/me/.rvm/rubies/ruby-1.9.3-p125/bin/ruby extconf.rb checking for ruby/thread.h... * extconf.rb failed * Could not create Makefile due to some reason, probably lack of necessary libraries and/or headers. Check the mkmf.log file for more details. You may need configuration options.

Provided configuration options: --with-opt-dir --with-opt-include --without-opt-include=${opt-dir}/include --with-opt-lib --without-opt-lib=${opt-dir}/lib --with-make-prog --without-make-prog --srcdir=. --curdir --ruby=/Users/me/.rvm/rubies/ruby-1.9.3-p125/bin/ruby /Users/me/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/1.9.1/mkmf.rb:381:in try_do': The compiler failed to generate an executable file. (RuntimeError)
You have to install development tools first.
from /Users/me/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/1.9.1/mkmf.rb:506:intry_cpp' from /Users/me/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/1.9.1/mkmf.rb:931:in block in have_header'
from /Users/me/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/1.9.1/mkmf.rb:790:inblock in checking_for' from /Users/me/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/1.9.1/mkmf.rb:284:in block (2 levels) in postpone'
from /Users/me/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/1.9.1/mkmf.rb:254:inopen' from /Users/me/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/1.9.1/mkmf.rb:284:in block in postpone'
from /Users/me/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/1.9.1/mkmf.rb:254:inopen' from /Users/me/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/1.9.1/mkmf.rb:280:in postpone'
from /Users/me/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/1.9.1/mkmf.rb:789:inchecking_for' from /Users/me/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/1.9.1/mkmf.rb:930:in have_header'
from extconf.rb:9:in'

从/Users/me/.rvm/gems/ruby-1.9.3-p125@mailcatcher/gems/mysql2-0.2.18/ext/mysql2/mkmf.log 复制:

"/usr/bin/gcc-4.2 -o conftest -I/Users/me/.rvm/rubies/ruby-1.9.3-p125/include/ruby-1.9.1/x86_64-darwin10.8.0 -I/Users/me/.rvm/rubies/ruby-1.9.3-p125/include/ruby-1.9.1/ruby/backward -I/Users/me/.rvm/rubies/ruby-1.9.3-p125/include/ruby-1.9.1 -I. -I/Users/me/.rvm/usr/include -D_XOPEN_SOURCE -D_DARWIN_C_SOURCE -O3 -ggdb -Wextra -Wno-unused-parameter -Wno-parentheses -Wno-long-long -Wno-missing-field-initializers -Wpointer-arith -Wwrite-strings -Wdeclaration-after-statement -Wshorten-64-to-32 -Wimplicit-function-declaration -fno-common -pipe conftest.c -L. -L/Users/me/.rvm/rubies/ruby-1.9.3-p125/lib -L/Users/me/.rvm/usr/lib -L. -L/usr/local/lib -lruby.1.9.1 -lpthread -ldl -lobjc " checked program was: /* begin / 1: #include "ruby.h" 2: 3: int main() {return 0;} / end */

Answer 1

听起来您可能缺少 XCode 命令行工具:
xcode-select --install


或者 mySQL 包:如果您还没有自制软件:
$/usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
然后安装mysql:
酿造安装mysql


我不记得过去是哪个解决了这个问题，但我确定是其中之一。