emacs-31 927a7fff5ec 2/2: Restore public interfaces for accessing built-in package info

branch: emacs-31
commit 927a7fff5ecd11057665dcd9a1bf4faa5aff0a45
Author: Xiyue Deng <[email protected]>
Commit: Philip Kaludercic <[email protected]>

    Restore public interfaces for accessing built-in package info
    
    These functions were removed in ab36f5892203e4b1f59da7c995e0f1fa0a81d1b6
    during the reorganization of package.el as part of Bug#80079.
    
    Also add a simple test for these functions to avoid future regressions.
    
    See also discussion at
    https://lists.gnu.org/archive/html/emacs-devel/2026-06/msg00149.html.
    
    * lisp/emacs-lisp/package.el (package-versioned-builtin-packages,
    package-builtin-package-version): Restore.
    * lisp/emacs-lisp/package-activate.el: Remove lingering comments.
    * test/lisp/emacs-lisp/package-tests.el
    (package-test-builtin-package-info): Add.
---
 lisp/emacs-lisp/package-activate.el   |  2 --
 lisp/emacs-lisp/package.el            | 16 ++++++++++++++++
 test/lisp/emacs-lisp/package-tests.el | 11 +++++++++++
 3 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/lisp/emacs-lisp/package-activate.el b/lisp/emacs-lisp/package-activate.el
index 53a3fa30836..5e2623c57f1 100644
--- a/lisp/emacs-lisp/package-activate.el
+++ b/lisp/emacs-lisp/package-activate.el
@@ -208,8 +208,6 @@ called via `package-activate-all'.  To change which packages are
 loaded and/or activated, customize `package-load-list'.")
 (put 'package-alist 'risky-local-variable t)
 
-;;;; Public interfaces for accessing built-in package info
-
 ;;;###autoload
 (defvar package-activated-list nil
   ;; FIXME: This should implicitly include all builtin packages.
diff --git a/lisp/emacs-lisp/package.el b/lisp/emacs-lisp/package.el
index cd3c850f7a4..12b450d93db 100644
--- a/lisp/emacs-lisp/package.el
+++ b/lisp/emacs-lisp/package.el
@@ -535,6 +535,22 @@ package."
   summary)
 
 
+;;; Public interfaces for accessing built-in package info
+
+(defun package-versioned-builtin-packages ()
+  "Return a list of all the versioned built-in packages.
+The return value is a list of names of built-in packages represented as
+symbols."
+  (mapcar #'car package--builtin-versions))
+
+(defun package-builtin-package-version (package)
+  "Return the version of a built-in PACKAGE given by its symbol.
+The return value is a list of integers representing the version of
+PACKAGE, in the format returned by `version-to-list', or nil if the
+package is built-in but has no version or is not a built-in package."
+  (alist-get package package--builtin-versions))
+
+
 ;;; Installed packages
 
 ;; The following functions are called on each installed package by
diff --git a/test/lisp/emacs-lisp/package-tests.el b/test/lisp/emacs-lisp/package-tests.el
index a2e4adb7b8e..b6fb9005e4c 100644
--- a/test/lisp/emacs-lisp/package-tests.el
+++ b/test/lisp/emacs-lisp/package-tests.el
@@ -1028,6 +1028,17 @@ but with a different end of line convention (bug#48137)."
             (list new-pkg-desc simple-depend-desc-2 simple-depend-desc-1
                   multi-file-desc simple-depend-desc simple-single-desc)))))
 
+(ert-deftest package-test-builtin-package-info ()
+  "Test public interfaces for querying package info."
+  (should (not (null (package-versioned-builtin-packages))))
+  ;; Picking any built-in library to check the version. Update results
+  ;; as needed.
+  (require 'lisp-mnt)
+  (should (equal (package-builtin-package-version 'cl-lib)
+                 (with-temp-buffer
+                   (insert-file-contents (locate-library "cl-lib.el"))
+                   (version-to-list (lm-version))))))
+
 (provide 'package-test)
 
 ;;; package-tests.el ends here