Bump minimum R version to 3.6.0 and make related tweaks (#7026)

* Bump to R >=3.6.0

* Remove `can_return_from_exit` guard

* Remove `...length()` and `...elt()` backports

* Remove version skip

* NEWS bullet

DESCRIPTION

@@ -20,7 +20,7 @@ License: MIT + file LICENSE
 URL: https://dplyr.tidyverse.org, https://github.com/tidyverse/dplyr
 BugReports: https://github.com/tidyverse/dplyr/issues
 Depends:
-    R (>= 3.5.0)
+    R (>= 3.6.0)
 Imports:
     cli (>= 3.6.2),
     generics,

NEWS.md

@@ -1,5 +1,7 @@
 # dplyr (development version)
 
+* R >=3.6.0 is now explicitly required (#7026).
+
 # dplyr 1.1.4
 
 * `join_by()` now allows its helper functions to be namespaced with `dplyr::`,

R/mutate.R

@@ -501,13 +501,9 @@ check_muffled_warning <- function(cnd) {
 
   # Cancel early exits, e.g. from an exiting handler. This way we can
   # still instrument caught warnings to avoid confusing
-  # inconsistencies. This doesn't work on versions of R older than
-  # 3.5.0 because they don't include this change:
-  # https://github.com/wch/r-source/commit/688eaebf. So with
-  # `tryCatch(warning = )`, the original warning `cnd` will be caught
-  # instead of the instrumented warning.
+  # inconsistencies.
   on.exit(
-    if (can_return_from_exit && early_exit) {
+    if (early_exit) {
       return(FALSE)
     }
   )
@@ -523,7 +519,3 @@ check_muffled_warning <- function(cnd) {
   early_exit <- FALSE
   muffled
 }
-
-on_load(
-  can_return_from_exit <- getRversion() >= "3.5.0"
-)

R/slice.R

@@ -358,13 +358,13 @@ slice_eval <- function(mask,
                        user_env = caller_env(2)) {
   index <- 0L
   impl <- function(...) {
-    n <- ...length2()
+    n <- ...length()
     out <- vector("list", n)
 
     for (i in seq_len(n)) {
       index <<- i
 
-      slice_idx <- ...elt2(i)
+      slice_idx <- ...elt(i)
 
       if (is.matrix(slice_idx) && ncol(slice_idx) == 1) {
         lifecycle::deprecate_warn(
@@ -588,17 +588,3 @@ on_load({
 dplyr_local_slice_by_arg <- function(by_arg, frame = caller_env()) {
   local_bindings(slice_by_arg = by_arg, .env = the, .frame = frame)
 }
-
-# Backports for R 3.5.0 utils
-...length2 <- function(frame = caller_env()) {
-  dots <- env_get(frame, "...")
-
-  if (is_missing(dots)) {
-    0L
-  } else {
-    length(dots)
-  }
-}
-...elt2 <- function(i, frame = caller_env()) {
-  eval_bare(sym(paste0("..", i)), frame)
-}

tests/testthat/helper-lazy.R

@@ -1,6 +1,4 @@
 skip_if_no_lazy_character <- function() {
-  skip_if(getRversion() <= "3.5.0")
-
   new_lazy_character <- import_vctrs("new_lazy_character", optional = TRUE)
   lazy_character_is_materialized <- import_vctrs("lazy_character_is_materialized", optional = TRUE)