Order of operators gets mangled when evaluating multiple !!ed expressions

[nstrayer]

If you nest expressions and then quote an expression using that nested expression, the nested expression gets modified and the operator order gets messed up. The following reprex illustrates the problem.

library(rlang)
x <- 1
xx <- quote(!!x / !!x)
xx
#> !!x/!!x
. <- expr(!!xx + 5)
xx
#> !!1/1

[nstrayer]

Longer-form reprex with session info:

library(rlang)
x <- 1
xx <- quote(!!x / !!x)
xx
#> !!x/!!x
. <- expr(!!xx + 5)
xx
#> !!1/1

sessioninfo::session_info()
#> ─ Session info ───────────────────────────────────────────────────────────────
#>  setting  value                       
#>  version  R version 4.0.2 (2020-06-22)
#>  os       macOS Catalina 10.15.7      
#>  system   x86_64, darwin17.0          
#>  ui       X11                         
#>  language (EN)                        
#>  collate  en_US.UTF-8                 
#>  ctype    en_US.UTF-8                 
#>  tz       America/Detroit             
#>  date     2021-01-29                  
#> 
#> ─ Packages ───────────────────────────────────────────────────────────────────
#>  package     * version    date       lib source                            
#>  assertthat    0.2.1      2019-03-21 [1] CRAN (R 4.0.2)                    
#>  backports     1.2.1      2020-12-09 [1] CRAN (R 4.0.2)                    
#>  cli           2.2.0.9000 2021-01-15 [1] Github (r-lib/cli@d2f1506)        
#>  crayon        1.3.4      2017-09-16 [1] CRAN (R 4.0.2)                    
#>  digest        0.6.27     2020-10-24 [1] CRAN (R 4.0.2)                    
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#>  evaluate      0.14       2019-05-28 [1] CRAN (R 4.0.1)                    
#>  fs            1.5.0      2020-07-31 [1] CRAN (R 4.0.2)                    
#>  glue          1.4.2      2020-08-27 [1] CRAN (R 4.0.2)                    
#>  highr         0.8        2019-03-20 [1] CRAN (R 4.0.2)                    
#>  htmltools     0.5.1      2021-01-12 [1] CRAN (R 4.0.2)                    
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#>  magrittr      2.0.1      2020-11-17 [1] CRAN (R 4.0.2)                    
#>  pillar        1.4.7      2020-11-20 [1] CRAN (R 4.0.2)                    
#>  pkgconfig     2.0.3      2019-09-22 [1] CRAN (R 4.0.2)                    
#>  purrr         0.3.4      2020-04-17 [1] CRAN (R 4.0.2)                    
#>  reprex        1.0.0      2021-01-27 [1] CRAN (R 4.0.2)                    
#>  rlang       * 0.4.10     2020-12-30 [1] CRAN (R 4.0.2)                    
#>  rmarkdown     2.6.6      2021-01-22 [1] Github (rstudio/rmarkdown@f573088)
#>  rstudioapi    0.13       2020-11-12 [1] CRAN (R 4.0.2)                    
#>  sessioninfo   1.1.1      2018-11-05 [1] CRAN (R 4.0.2)                    
#>  stringi       1.5.3      2020-09-09 [1] CRAN (R 4.0.2)                    
#>  stringr       1.4.0      2019-02-10 [1] CRAN (R 4.0.2)                    
#>  styler        1.3.2      2020-02-23 [1] CRAN (R 4.0.2)                    
#>  tibble        3.0.5      2021-01-15 [1] CRAN (R 4.0.0)                    
#>  vctrs         0.3.6      2020-12-17 [1] CRAN (R 4.0.2)                    
#>  withr         2.3.0      2020-09-22 [1] CRAN (R 4.0.2)                    
#>  xfun          0.20       2021-01-06 [1] CRAN (R 4.0.2)                    
#>  yaml          2.2.1      2020-02-01 [1] CRAN (R 4.0.2)                    
#> 
#> [1] /Library/Frameworks/R.framework/Versions/4.0/Resources/library