“Using an external vector in selections was deprecated in tidyselect 1.1.0.”

I am wondering what tidyselect::all_of() is doing to the character vector that allows downstream functions like e.g. dplyr::select() to recognise that all_of() has been used. If I inspect (with class() or attributes()) the stand alone output of an all_of() call I can’t find any indications.

Example:

library(dplyr) # 1.0.10
library(tidyselect) # 1.2.0

my_var <- c("Petal.Length", "Petal.Width")

# No Warning
iris %>%
  select(all_of(my_var))

# Triggers Using an external vector in selections was deprecated in tidyselect 1.1.0.
iris %>%
  select(my_var)