Squashed commit of the following:

commit 7ea4fa7
Author: Kirill Müller <kirill@cynkra.com>
Date:   Fri Jan 23 17:12:53 2026 +0100

    feat: Add `date` and `overwrite` arguments to `cpp_vendor()`

commit 6ea648d
Author: Kirill Müller <kirill@cynkra.com>
Date:   Fri Jan 23 15:45:04 2026 +0100

    Squashed commit of the following:

    commit 8b16df3
    Author: Kirill Müller <krlmlr@users.noreply.github.com>
    Date:   Thu Jan 22 07:37:45 2026 +0100

        Formatting

    commit f557b0b
    Author: Kirill Müller <krlmlr@users.noreply.github.com>
    Date:   Thu Jan 22 07:35:10 2026 +0100

        Clarify

    commit ac9756b
    Author: Kirill Müller <krlmlr@users.noreply.github.com>
    Date:   Thu Jan 22 07:06:41 2026 +0100

        Remove

    commit 64be6e7
    Author: Copilot <198982749+Copilot@users.noreply.github.com>
    Date:   Thu Jan 22 07:05:34 2026 +0100

        Add test for external_pointer attribute preservation and fix move assignment operator (r-lib#486)

        Co-authored-by: krlmlr <1741643+krlmlr@users.noreply.github.com>
        Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>

    commit 1db6beb
    Author: Kirill Müller <kirill@cynkra.com>
    Date:   Sat Dec 7 20:47:09 2024 +0100

        fix: Avoid premature release for external pointers

commit e1e31b8
Author: Kirill Müller <kirill@cynkra.com>
Date:   Fri Jan 23 15:45:04 2026 +0100

    Squashed commit of the following:

    commit 1807106
    Author: Kirill Müller <kirill@cynkra.com>
    Date:   Sat Dec 7 20:45:20 2024 +0100

        fix: Copy strings before calling `Rf_warningcall()` to avoid weird unwind behavior

commit c255629
Author: Kirill Müller <kirill@cynkra.com>
Date:   Fri Jan 23 15:45:04 2026 +0100

    Squashed commit of the following:

    commit 0e20f8f
    Author: Kirill Müller <kirill@cynkra.com>
    Date:   Sat Dec 7 20:42:58 2024 +0100

        feat: New `END_CPP11_EX()` macro that allows parameterizing the return value

commit 579dbcf
Author: Kirill Müller <kirill@cynkra.com>
Date:   Fri Jan 23 15:45:04 2026 +0100

    Squashed commit of the following:

    commit d17d404
    Author: Kirill Müller <kirill@cynkra.com>
    Date:   Sat Dec 7 20:39:59 2024 +0100

        Format

    commit 35fe905
    Author: Kirill Müller <kirill@cynkra.com>
    Date:   Sat Dec 7 20:38:22 2024 +0100

        feat: Add `prot` argument to `external_pointer()` constructor

commit db81744
Author: Kirill Müller <kirill@cynkra.com>
Date:   Fri Jan 23 15:45:03 2026 +0100

    Squashed commit of the following:

    commit 6a9c76c
    Author: Kirill Müller <kirill@cynkra.com>
    Date:   Mon Oct 23 09:47:00 2023 +0200

        Vectorize file argument to cpp_source()

Author: krlmlr

R/vendor.R

@@ -30,11 +30,15 @@
 #'
 #' # cleanup
 #' unlink(dir, recursive = TRUE)
-cpp_vendor <- function(path = ".") {
+cpp_vendor <- function(path = ".", date = Sys.Date(), overwrite = FALSE) {
   new <- file.path(path, "inst", "include", "cpp11")
 
   if (dir.exists(new)) {
-    stop("'", new, "' already exists\n * run unlink('", new, "', recursive = TRUE)", call. = FALSE)
+    if (overwrite) {
+      unlink(new, recursive = TRUE)
+    } else {
+      stop("'", new, "' already exists\n * run unlink('", new, "', recursive = TRUE)", call. = FALSE)
+    }
   }
 
   dir.create(new , recursive = TRUE, showWarnings = FALSE)
@@ -46,7 +50,7 @@ cpp_vendor <- function(path = ".") {
 
   cpp11_version <- utils::packageVersion("cpp11")
 
-  cpp11_header <- sprintf("// cpp11 version: %s\n// vendored on: %s", cpp11_version, Sys.Date())
+  cpp11_header <- sprintf("// cpp11 version: %s\n// vendored on: %s", cpp11_version, as.Date(date))
 
   files <- list.files(current, full.names = TRUE)