vc-hg-checkin-patch: Add implementation for Hg

* lisp/vc/vc-hg.el (vc-hg-checkin-patch): Add Hg-specific
implementation (bug#52349), like suggested in
https://lists.gnu.org/archive/html/emacs-devel/2022-10/msg01533.html.
(vc-hg--extract-headers): Extract from vc-hg-checkin.

1 files changed, 26 insertions, 10 deletions

diff --git a/lisp/vc/vc-hg.el b/lisp/vc/vc-hg.el
index 2eebe2d5434..1b1c1683dd5 100644
--- a/lisp/vc/vc-hg.el
+++ b/lisp/vc/vc-hg.el
@@ -51,6 +51,7 @@
 ;; - receive-file (file rev)                   ?? PROBABLY NOT NEEDED
 ;; - unregister (file)                         OK
 ;; * checkin (files rev comment)               OK
+;; - checkin-patch (patch-string comment)      OK
 ;; * find-revision (file rev buffer)           OK
 ;; * checkout (file &optional rev)             OK
 ;; * revert (file &optional contents-done)     OK
@@ -1189,16 +1190,31 @@ It is based on `log-edit-mode', and has Hg-specific extensions.")
 (defun vc-hg-checkin (files comment &optional _rev)
   "Hg-specific version of `vc-backend-checkin'.
 REV is ignored."
-  (let ((amend-extract-fn
-         (lambda (value)
-           (when (equal value "yes")
-             (list "--amend")))))
-    (apply #'vc-hg-command nil 0 files
-           (nconc (list "commit" "-m")
-                  (log-edit-extract-headers `(("Author" . "--user")
-                                              ("Date" . "--date")
-                                              ("Amend" . ,amend-extract-fn))
-                                            comment)))))
+  (apply #'vc-hg-command nil 0 files
+         (nconc (list "commit" "-m")
+                (vc-hg--extract-headers comment))))
+
+(defun vc-hg-checkin-patch (patch-string comment)
+  (let ((patch-file (make-temp-file "hg-patch")))
+    (write-region patch-string nil patch-file)
+    (unwind-protect
+        (progn
+          (apply #'vc-hg-command nil 0 nil
+                 (nconc (list "import" "--bypass" patch-file "-m")
+                        (vc-hg--extract-headers comment)))
+          (vc-hg-command nil 0 nil
+                         "update"
+                         "--merge" "--tool" "internal:local"
+                         "tip"))
+      (delete-file patch-file))))
+
+(defun vc-hg--extract-headers (comment)
+  (log-edit-extract-headers `(("Author" . "--user")
+                              ("Date" . "--date")
+                              ("Amend" . (lambda (value)
+                                           (when (equal value "yes")
+                                             (list "--amend")))))
+                            comment))
 
 (defun vc-hg-find-revision (file rev buffer)
   (let ((coding-system-for-read 'binary)