Fix 'd' command in 'query-replace' in buffers not visiting files

* lisp/vc/diff.el (diff-file-local-copy): Use proper coding-system
when writing a local copy of a non-file visiting buffer.

* lisp/misearch.el (coding-system--for-buffer-diff): New variable.
(multi-file-replace-as-diff): Bind it to 'utf-8-emacs'.
(multi-file-diff-no-select): Use proper coding-system when reading
output of Diff.  (Bug#79761)

1 files changed, 5 insertions, 1 deletions

diff --git a/lisp/vc/diff.el b/lisp/vc/diff.el
index c8a1b7c0efa..9e4a5349fef 100644
--- a/lisp/vc/diff.el
+++ b/lisp/vc/diff.el
@@ -118,13 +118,17 @@ Non-interactively, OLD and NEW may each be a file or a buffer."
   (display-buffer
    (diff-no-select old new switches no-async)))
 
+(defvar coding-system--for-buffer-diff) ; from misearch.el
+
 (defun diff-file-local-copy (file-or-buf)
   "Like `file-local-copy' but also supports a buffer as the argument.
 When FILE-OR-BUF is a buffer, return the filename of a local
 temporary file with the buffer's contents."
   (if (bufferp file-or-buf)
       (with-current-buffer file-or-buf
-        (let ((tempfile (make-temp-file "buffer-content-")))
+        (let ((tempfile (make-temp-file "buffer-content-"))
+              (coding-system-for-write (or coding-system--for-buffer-diff
+                                           coding-system-for-write)))
           (if diff-entire-buffers
               (write-region nil nil tempfile nil 'nomessage)
             (write-region (point-min) (point-max) tempfile nil 'nomessage))