Add warning/documentation of assignment pipe incompatibility with base pipe

[gvelasq]

Thank you for magrittr, it remains one of my favorite R packages. This issue aims to follow-up on #269 and #253 (comment). In those issues, it was mentioned that building a compatibility layer between %<>% and |> is out of scope for magrittr.

For those who prefer to use %<>% (carefully) for its conciseness despite prior style guidance, especially those who have switched their default pipe operator to |> or are migrating codebases from %>% to |>, this may lead to silent errors like the one below:

# 1. setup ----
library(dplyr, warn.conflicts = FALSE)
library(magrittr)

# 2. data ----
a <- tibble(mtcars)

# 3. console output ----
# the immediately-provided console output shows the expected computation
a %<>%
  select(cyl) |>
  mutate(cyl2 = cyl) |>
  filter(cyl2 == 6)
#> # A tibble: 7 × 2
#>     cyl  cyl2
#>   <dbl> <dbl>
#> 1     6     6
#> 2     6     6
#> 3     6     6
#> 4     6     6
#> 5     6     6
#> 6     6     6
#> 7     6     6

# 4. assigned value ----
# the assigned value of `a` stores only the pipeline steps before the first |>
a
#> # A tibble: 32 × 1
#>      cyl
#>    <dbl>
#>  1     6
#>  2     6
#>  3     4
#>  4     6
#>  5     8
#>  6     6
#>  7     8
#>  8     4
#>  9     4
#> 10     6
#> # ℹ 22 more rows

Would the maintainers consider either of the following to avoid silent errors?

1. Build in a warning message when %<>% is used together with |> in a pipeline. This would only be possible if the presence of |> can be detected.
2. Add a note in the documentation for %<>% that it is incompatible / should not be used with |>.

Thank you for considering.

^{Created on 2025-08-01 with reprex v2.1.1}

[lionel-]

There is no way to detect |> is being used because it's a parser operation, not a runtime one.

I agree we should document the limitation.