我过去在windows下成功安装了带有ruby的gem mysql2，但现在它显示出一个奇怪的错误
checking for main() in -llibmysql... no
没有拼写错误，我的控制台真的显示-llibmysql而不是-libmysql（我认为它应该只是libmysql而没有任何破折号）
我已按照this link的所有说明操作，我的命令看起来像
gem install mysql2 -- '--with-mysql-lib="c:\Dev\MySQL_Connector\lib" --with-mysql-include="c:\Dev\MySQL_Connector\include"'
...
ERROR: Error installing mysql2:
ERROR: Failed to build gem native extension.
C:/Bibliotheques/Dev/Ruby200-x64/bin/ruby.exe extconf.rb --with-mysql-lib=c:\Dev\MySQL_Connector\lib --with-mysql-in
clude=c:\Dev\MySQL_Connector\include
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
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Using --with-mysql-dir=c:\Dev\MySQL_Connector
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checking for main() in -llibmysql... no