From e8abbb8af19d9517a451fd402118e409c1a690b8 Mon Sep 17 00:00:00 2001
From: Michael Chirico <chiricom@google.com>
Date: Fri, 27 Mar 2026 21:17:53 +0000
Subject: [PATCH 1/3] Adapt to utils:::print.bitstring

---
 NAMESPACE                       |  1 -
 NEWS.md                         |  3 ++-
 R/integer64.R                   |  9 ++-------
 R/zzz.R                         | 14 +++++++++++++-
 tests/testthat/test-integer64.R |  4 ++++
 5 files changed, 21 insertions(+), 10 deletions(-)

diff --git a/NAMESPACE b/NAMESPACE
index d80abdf4..1b036627 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -130,7 +130,6 @@ S3method(ordertie,integer64)
 S3method(orderuni,integer64)
 S3method(orderupo,integer64)
 S3method(prank,integer64)
-S3method(print,bitstring)
 S3method(print,cache)
 S3method(print,integer64)
 S3method(prod,integer64)
diff --git a/NEWS.md b/NEWS.md
index c58f5e2b..302add15 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -82,7 +82,8 @@
 ## NOTES
 
 1. {bit64} no longer prints any start-up messages through an `.onAttach()` hook (#106). Thanks @hadley for the request.
-2. The R version dependency has been bumped from 3.4.0 (2017) to 3.5.0 (2018).
+1. The R version dependency has been bumped from 3.4.0 (2017) to 3.5.0 (2018).
+1. From R 4.6.0, R's {utils} package has its own 'bitstring' class which is basically compatible with that shipped by {bit64} for many years. `as.bitstring()` only makes a simple adjustment, namely, for `as.bitstring()` to add two new attributes (`nbits` and `type`). Everything else should continue to work as before.
 
 ## BUG FIXES
 
diff --git a/R/integer64.R b/R/integer64.R
index 8537ab53..3c7ee800 100644
--- a/R/integer64.R
+++ b/R/integer64.R
@@ -695,6 +695,8 @@ as.character.integer64 = function(x, ...)
 as.bitstring.integer64 = function(x, ...) {
   ret = .Call(C_as_bitstring_integer64, x, rep(NA_character_, length(x)))
   oldClass(ret) = 'bitstring'
+  attr(ret, 'nbits') = c(1L, 63L)
+  attr(ret, 'type') = "int64"
   ret
 }
 
@@ -780,13 +782,6 @@ factor = function(x=character(), levels, labels=levels, exclude=NA, ordered=is.o
 #' @export
 ordered = function(x=character(), ...) factor(x, ..., ordered=TRUE)
 
-#' @rdname as.character.integer64
-#' @export
-print.bitstring = function(x, ...) {
-  oldClass(x) = minusclass(class(x), 'bitstring')
-  NextMethod(x)
-}
-
 #' @rdname as.integer64.character
 #' @export
 as.integer64.bitstring = function(x, ...) {
diff --git a/R/zzz.R b/R/zzz.R
index 51f59bd1..afecbc25 100644
--- a/R/zzz.R
+++ b/R/zzz.R
@@ -15,7 +15,7 @@ if (getRversion() < "3.6.0") {
     class(obj) = c(class, "error", "condition")
     obj
   }
-  
+
   warningCondition = function(message, ..., class = NULL, call = NULL) {
     obj <- list(message = as.character(message), call = call, ...)
     class(obj) = c(class, "warning", "condition")
@@ -23,6 +23,18 @@ if (getRversion() < "3.6.0") {
   }
 }
 
+.onLoad = function(libname, pkgname) {
+  # TODO(R >= 4.6.0): remove this.
+  if (!utils::isS3method("print.bitstring")) {
+    registerS3method("print", "bitstring", function(x, ...) {
+      reset_class = minusclass(class(x), 'bitstring')
+      attributes(x) = NULL
+      oldClass(x) = reset_class
+      NextMethod(x)
+    })
+  }
+}
+
 .onAttach = function(libname, pkgname) {
   packageStartupMessage( # in **bold**
     "\033[1mThe assignment of character values to integer64 vectors and ",
diff --git a/tests/testthat/test-integer64.R b/tests/testthat/test-integer64.R
index bc36015d..11215f09 100644
--- a/tests/testthat/test-integer64.R
+++ b/tests/testthat/test-integer64.R
@@ -1573,3 +1573,7 @@ test_that("back-compatible keep.names=TRUE is supported for limited input classe
   y = c(a = 1.0)
   expect_named(as.integer64(y, keep.names=TRUE), "a")
 })
+
+test_that("bitstring class meshes with R's own (from 4.6.0)", {
+  expect_no_error(print(as.bitstring(lim.integer64())))
+})

From 12bd40bf9a70a3fda5857b92283e41fdc85c555a Mon Sep 17 00:00:00 2001
From: Michael Chirico <chiricom@google.com>
Date: Fri, 27 Mar 2026 21:23:20 +0000
Subject: [PATCH 2/3] expect_no_error for ancient

---
 .devcontainer/r-350/.Rprofile | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/.devcontainer/r-350/.Rprofile b/.devcontainer/r-350/.Rprofile
index d4e64580..a49336cc 100644
--- a/.devcontainer/r-350/.Rprofile
+++ b/.devcontainer/r-350/.Rprofile
@@ -98,11 +98,17 @@ expect_no_warning <- function(object, ...) {
 }
 
 expect_error = function(expr, msg, ...) {
-  val = tryCatch(expr, error = identity)
+  val = tryCatch(expr, error=identity)
   stopifnot(inherits(val, "error") && grepl(msg, conditionMessage(val), ...))
   cat(".")
 }
 
+expect_no_error = function(expr) {
+  val = tryCatch(expr, error=identity)
+  stopifnot(!inherits(val, "error"))
+  cat(".")
+}
+
 expect_s3_class = function(x, kls) { stopifnot(inherits(x, kls)); cat(".") }
 expect_length = function(x, l) expect_identical(length(x), l)
 

From 1b0e693d776e6baff877921b32f883f9fc1dbddf Mon Sep 17 00:00:00 2001
From: Michael Chirico <chiricom@google.com>
Date: Fri, 27 Mar 2026 21:30:49 +0000
Subject: [PATCH 3/3] remove .Rd references

---
 man/as.character.integer64.Rd | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/man/as.character.integer64.Rd b/man/as.character.integer64.Rd
index 769ce956..391a6140 100644
--- a/man/as.character.integer64.Rd
+++ b/man/as.character.integer64.Rd
@@ -15,7 +15,6 @@
 \alias{as.POSIXlt.integer64}
 \alias{as.factor}
 \alias{as.ordered}
-\alias{print.bitstring}
 \alias{as.list.integer64}
 \title{Coerce from integer64}
 \usage{
@@ -47,8 +46,6 @@ as.factor(x)
 
 as.ordered(x)
 
-\method{print}{bitstring}(x, ...)
-
 \method{as.list}{integer64}(x, ...)
 }
 \arguments{