Add vec_ptype.POSIXlt() and related tests

NAMESPACE

@@ -327,6 +327,7 @@ S3method(vec_proxy_order,array)
 S3method(vec_proxy_order,default)
 S3method(vec_proxy_order,list)
 S3method(vec_proxy_order,raw)
+S3method(vec_ptype,POSIXlt)
 S3method(vec_ptype2,AsIs)
 S3method(vec_ptype2,Date)
 S3method(vec_ptype2,POSIXct)

R/type-date-time.R

@@ -133,6 +133,22 @@ vec_ptype_abbr.difftime <- function(x, ...) {
   "drtn"
 }
 
+# Ptype -------------------------------------------------------------------
+
+#' @export
+vec_ptype.POSIXlt <- function(x, ...) {
+  # `vec_ptype2()` pushes towards `POSIXct`. In theory, maybe `vec_ptype()`
+  # should as well so that `vec_c(<POSIXlt>)` and `vec_c(<POSIXlt>, <POSIXlt>)`
+  # are consistent and both return `POSIXct`. In practice this broke a number of
+  # packages (datetimeoffset, slider, nanoarrow), and also generally means that
+  # you wouldn't be able to provide a `POSIXlt` as a `ptype` argument to
+  # anything and expect it to return a `POSIXlt` as output. So we've decided to
+  # just leave this inconsistency. Getting `POSIXlt` attributes exactly right
+  # is very tricky, and very R version dependent, so we just consistency align
+  # with `[` here and in tests.
+  x[0]
+}
+
 # Coerce ------------------------------------------------------------------
 
 #' @rdname new_date

tests/testthat/test-type-date-time.R

@@ -146,7 +146,18 @@ test_that("tz comes from first non-empty", {
   expect_identical(vec_ptype2(z, y), z[0])
 })
 
-test_that("POSIXlt always steered towards POSIXct", {
+test_that("POSIXlt remains POSIXlt in vec_ptype()", {
+  # See `vec_ptype.POSIXlt()` for details
+  x <- as.POSIXlt("2020-01-01", tz = "UTC")
+  exp <- x[0]
+  expect_identical(vec_ptype(x), exp)
+
+  x <- as.POSIXlt("2020-01-01", tz = "America/New_York")
+  exp <- x[0]
+  expect_identical(vec_ptype(x), exp)
+})
+
+test_that("POSIXlt always steered towards POSIXct in vec_ptype2()", {
   dtc <- as.POSIXct("2020-01-01", tz = "UTC")
   dtl <- as.POSIXlt("2020-01-01", tz = "UTC")
 
@@ -192,6 +203,27 @@ test_that("vec_ptype2() standardizes duration storage type to double", {
   expect_identical(vec_ptype2(x, x), expect)
 })
 
+test_that("vec_ptype_common() gives expected results with <POSIXlt>", {
+  # See `vec_ptype.POSIXlt()` for details
+  x <- as.POSIXlt("2020-01-01", tz = "UTC")
+
+  # `vec_ptype(x)` returns `<POSIXlt>`
+  exp <- x[0]
+  expect_identical(vec_ptype_common(x), exp)
+  expect_identical(vec_ptype_common(.ptype = x), exp)
+
+  # `vec_ptype2(x, x)` returns `<POSIXct>`
+  exp <- new_datetime(tzone = "UTC")
+  expect_identical(vec_ptype_common(x, x), exp)
+
+  # With <unspecified> input, still uses `vec_ptype(x)`, so returns `<POSIXlt>`
+  exp <- x[0]
+  expect_identical(vec_ptype_common(x, NA), exp)
+  expect_identical(vec_ptype_common(NA, x), exp)
+  expect_identical(vec_ptype_common(x, NULL), exp)
+  expect_identical(vec_ptype_common(NULL, x), exp)
+})
+
 # cast: dates ---------------------------------------------------------------
 
 test_that("safe casts work as expected", {