Deprecating an argument

Use lifecycle::deprecated() with lifecycle::deprecate_warn().

write_file <- function(x,
                       file,
                       append = FALSE,
                       path = deprecated()) {
  if (is_present(path)) {
    lifecycle::deprecate_warn("1.4.0", "write_file(path)", "write_file(file)")
    file <- path
  }
  ...
}

readr::write_file("hi", path = tempfile("lifecycle-demo-"))
#> Warning: The `path` argument of `write_file()` is deprecated as of readr
#> 1.4.0.
#> ℹ Please use the `file` argument instead.