unnecessary_concatenation_linter wrongly complains about usage with magrittr's assignment pipe operator %<>%

[salim-b]

Consider the following reprex:

tmp_file <- tempfile(fileext = "R")
writeLines(con = tmp_file,
           text = "
library(magrittr)
x <- 1:2
x %<>% c(3)
x
")

lintr::lint(filename = tmp_file,
            linters = list(lintr::unnecessary_concatenation_linter()))
#> /tmp/RtmpyaBMnL/filee0674c13fd78R:4:8: style: [unnecessary_concatenation_linter] Unneeded concatenation of a constant. Remove the "c" call.
#> x %<>% c(3)
#>        ^~~~

^{Created on 2023-07-20 with reprex v2.0.2}

x %<>% c(3) above is the magrittr way to write x <- c(x, 3), so lintr should ideally allow c() with a single constant if it is preceded by the %<>% operator.

[MichaelChirico]

Thanks Salim. I'm not exactly sure how to proceed.

On the one hand, the assignment pipe is not allowed by the Tidyverse guide:

https://style.tidyverse.org/pipes.html#assignment-2

on the other hand, that's kind of independent of the concatenation linter.

Probably we should:

1. lint this with assignment_linter()
2. not lint it with unnecessary_concatenation_linter()

[salim-b]

I know the TSG instructs to avoid this operator, but I still ike to use it. Thus I very much agree with your second action point.