YCMvim插件没有识别C++头文件

在.vimrc文件中添加以下代码：

let g:ycm_global_ycm_extra_conf = '~/ycm_extra_conf.py'

let g:ycm_collect_identifiers_from_tags_files = 1

let g:ycm_seed_identifiers_with_syntax = 1

let g:ycm_complete_in_comments = 1

let g:ycm_complete_in_strings = 1

let g:ycm_use_ultisnips_completer = 1

let g:ycm_filetype_blacklist = {}

let g:ycm_filetype_whitelist = {}

let g:ycm_semantic_triggers = {'c': ['.'], 'cpp': ['::'], 'python': ['.']}

let g:ycm_seed_identifiers_with_ctags = 1

let g:ycm_server_python_interpreter = '/usr/bin/python3'

let g:ycm_server_port = 12345

let g:ycm_confirm_extra_conf = 0

let g:ycm_show_diagnostics_ui = 0

let g:ycm_enable_diagnostic_highlighting = 0

let g:ycm_diagnostic_delay_seconds = 1

let g:ycm_key_invoke_completion = '<c-x><c-o>'

其中，g:ycm_global_ycm_extra_conf指定了YCM的配置文件路径，g:ycm_semantic_triggers设置了触发语义补全的符号，例如“::”，g:ycm_server_python_interpreter指定了YCM服务器端使用的Python解释器。

此外，还需在项目的根目录下创建一个名为.ycm_extra_conf.py的文件，内容为：

import os
import ycm_core

flags = [
'-Wall',
'-Werror',
'-Wextra',
'-pedantic',
'-I',
'./include',
'-isystem',
'/usr/include',
'-isystem',
'/usr/local/include',
'-isystem',
'/usr/include/c++/8.3.0'
]

def FlagsForFile(filename):
  return {
    'flags': flags,
    'do_cache': True
  }

其中，flags设置编译选项，例如头文件搜索路径等。

保存.vimrc和.ycm_extra_conf.py文件后，重新打开vim，便可以使用YCM插件的语义补全功能了。