LaTeX 编译 acmart 文档报错：No country present for an affiliation.

在编译一篇从 arXiv 下载的文档时遇到如下错误：

Class acmart Error: No country present for an affiliation.

有两种解决方案：

1. 将错误降级为警告

   在 \documentclass[xxx]{acmart} 后添加如下代码：

   \makeatletter
   \def\@ACM@checkaffil{% Only warnings
       \if@ACM@instpresent\else
       \ClassWarningNoLine{\@classname}{No institution present for an affiliation}%
       \fi
       \if@ACM@citypresent\else
       \ClassWarningNoLine{\@classname}{No city present for an affiliation}%
       \fi
       \if@ACM@countrypresent\else
           \ClassWarningNoLine{\@classname}{No country present for an affiliation}%
       \fi
   }
   \makeatother
   

2. 为每个作者添加空的 country 信息

   在每个作者的 \affiliation 代码块中添加 \country{}

   \author{Xxx Xxx}
   \affiliation{
       \institution{xxx}
       \country{}  % 添加这行
   }
   

参考：How to make acmart stop complaining about missing country in affiliation? | StackExchange