黄色三角形显示：expression result unused；
红色叉叉显示：reference to overloaded function could not be resolved;did you mean to call it?
下面是我的.ycm_extra_conf.py配置
不好意思自己的头文件位置找错了,不应该用网上帮你配制或者是默认的，具体的头文件位置还是要自己配制！
倒数第五行替换换成下列
'/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.11.sdk/usr/include'
运行 echo | clang -std=c++11 -stdlib=libc++ -v -E -x c++ - 找到系统的头文件，加入-isystem里面。如果你用了homebrew安装了各种包的话，也需要把include加入-isystem里面，应该是'/usr/local/include',。
我的ycm_config里面是这样的
53 'c++',
54 '-isystem', #Mark as system header
55 #Using `echo | clang -std=c++11 -stdlib=libc++ -v -E -x c++ -` to generate the following infos
56 '/usr/local/include',
57 '-isystem',
58 '/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1',
59 '-isystem',
60 '/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../lib/clang/7.0.0/include',
61 '-isystem',
62 '/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include',
63 '-isystem',
64 '/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.11.sdk/usr/include',
65 '-isystem',
66 '/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.11.sdk/System/Library/Frameworks',