从github安装软件包时出现以下错误：

> devtools::install_github("pmartinezarbizu/pairwiseAdonis/pairwiseAdonis")
Downloading GitHub repo pmartinezarbizu/pairwiseAdonis@HEAD
Erro: Failed to install 'pairwiseAdonis' from GitHub:
  System command 'Rcmd.exe' failed, exit status: -1, stdout + stderr empty

使用find_rtools，我得到以下消息（我正在阅读这些帖子，但无法解决我的问题：https://github.com/r-lib/devtools/issues/2031和R CMD检查未在Rtools目录中查找gcc）：

> find_rtools(T)
Scanning R CMD config CC...
cc_path:  
'' does not exist
Scanning path...
ls: C:\Rtools\bin\ls.exe 
gcc_path: C:\Rtools\mingw_64\bin\gcc.exe 
VERSION.txt
Rtools version 3.5.0.4 
Version: 3.5 
Found compatible gcc on path
[1] TRUE

我使用的是R v. 3.6.：

>     > session_info()
>     - Session info -------------------------------------------------------------------------------------
>      setting  value                       
>      version  R version 3.6.3 (2020-02-29)
>      os       Windows 10 x64              
>      system   x86_64, mingw32             
>      ui       RStudio                     
>      language (EN)                        
>      collate  Portuguese_Brazil.1252      
>      ctype    Portuguese_Brazil.1252      
>      tz       America/Sao_Paulo           
>      date     2020-07-29