[R] Allow package name prefix inside dplyr::across's .fns argument

[asfimport]

This is not a major issue, but may be worth mentioning as a known limitation.

library(dplyr, warn.conflicts = FALSE)
library(dplyr, warn.conflicts = FALSE)
mtcars |> arrow::arrow_table() |> mutate(across(starts_with("c"), base::as.character)) |> collect()
#> Error in base(cyl): could not find function "base"

Reporter: SHIMA Tatsuya / @eitsupi
Assignee: Nicola Crane / @thisisnic

PRs and other links:

• GitHub Pull Request #14279

_{Note: This issue was originally created as ARROW-17724. Please see the migration documentation for further details.}

[asfimport]

Nicola Crane / @thisisnic:
Nicely spotted. This is due to is.name((fns)) in the across_setup() function evaluating to TRUE for as.character and FALSE for base::as.character. Adding is.call(fns) to the list of conditions for identifying single functions may work (needs testing to confirm), or potentially replacing is.name(fns) with is.call(fns) or another function entirely.

[asfimport]

Nicola Crane / @thisisnic:
Issue resolved by pull request 14279
#14279