Provide option to forward Gnus messages with all (most) headers

Bug#67520

* lisp/gnus/gnus-msg.el (gnus-summary-mail-forward): Accept symbolic
prefix to let-bind message-forward-included-headers to nil, which will
include most original message headers in the forwarded copy.
(gnus-summary-post-forward): Corresponding arglist update.

2 files changed, 34 insertions, 18 deletions

diff --git a/doc/misc/gnus.texi b/doc/misc/gnus.texi
index 586e4b94ba1..ead5954a96e 100644
--- a/doc/misc/gnus.texi
+++ b/doc/misc/gnus.texi
@@ -5868,15 +5868,23 @@ original message but ignore the @code{Reply-To} field
 @findex gnus-summary-mail-forward
 @c @icon{gnus-summary-mail-forward}
 Forward the current article to some other person
-(@code{gnus-summary-mail-forward}).  If no prefix is given, the message
-is forwarded according to the value of (@code{message-forward-as-mime})
-and (@code{message-forward-show-mml}); if the prefix is 1, decode the
-message and forward directly inline; if the prefix is 2, forward message
-as an rfc822 @acronym{MIME} section; if the prefix is 3, decode message and
-forward as an rfc822 @acronym{MIME} section; if the prefix is 4, forward message
-directly inline; otherwise, the message is forwarded as no prefix given
-but use the flipped value of (@code{message-forward-as-mime}).  By
-default, the forwarded message is inlined into the mail.
+(@code{gnus-summary-mail-forward}).  If no prefix is given, the
+message is forwarded according to the value of
+(@code{message-forward-as-mime}) and
+(@code{message-forward-show-mml}); if the prefix is 1, decode the
+message and forward directly inline; if the prefix is 2, forward
+message as an rfc822 @acronym{MIME} section; if the prefix is 3,
+decode message and forward as an rfc822 @acronym{MIME} section; if the
+prefix is 4, forward message directly inline; otherwise, the message
+is forwarded as no prefix given but use the negated value of
+(@code{message-forward-as-mime}).  By default, the forwarded message
+is inlined into the mail.
+
+Which headers from the original message are included in the forwarded
+message is determined by options specific to @code{message-mode},
+@pxref{Forwarding,,, message}.  In addition, this command can be given
+the symbolic prefix @samp{a}, using @kbd{M-i a}, to include most original
+headers.
 
 @item S m
 @itemx m
diff --git a/lisp/gnus/gnus-msg.el b/lisp/gnus/gnus-msg.el
index b065ae34851..e503ccae00f 100644
--- a/lisp/gnus/gnus-msg.el
+++ b/lisp/gnus/gnus-msg.el
@@ -1209,7 +1209,7 @@ The original article(s) will be yanked."
   (gnus-summary-reply
    (gnus-summary-work-articles n) t (gnus-summary-work-articles n)))
 
-(defun gnus-summary-mail-forward (&optional arg post)
+(defun gnus-summary-mail-forward (&optional arg all-headers post)
   "Forward the current message(s) to another user.
 If process marks exist, forward all marked messages;
 if ARG is nil, see `message-forward-as-mime' and `message-forward-show-mml';
@@ -1217,17 +1217,25 @@ if ARG is 1, decode the message and forward directly inline;
 if ARG is 2, forward message as an rfc822 MIME section;
 if ARG is 3, decode message and forward as an rfc822 MIME section;
 if ARG is 4, forward message directly inline;
-otherwise, use flipped `message-forward-as-mime'.
+otherwise, use negated `message-forward-as-mime'.
 If POST, post instead of mail.
-For the \"inline\" alternatives, also see the variable
-`message-forward-ignored-headers'."
-  (interactive "P" gnus-summary-mode)
+If symbolic prefix ALL-HEADERS is the symbol `a', include all
+original headers in the forwarded message, except those matching
+`message-forward-ignored-headers'.  Otherwise, include headers
+based on the options `message-forward-included-headers',
+`message-forward-ignored-headers', and potentially
+`message-forward-included-mime-headers'."
+  (interactive (gnus-interactive "P\ny") gnus-summary-mode)
   (if (cdr (gnus-summary-work-articles nil))
       ;; Process marks are given.
       (gnus-uu-digest-mail-forward nil post)
     ;; No process marks.
     (let ((message-forward-as-mime message-forward-as-mime)
-          (message-forward-show-mml message-forward-show-mml))
+          (message-forward-show-mml message-forward-show-mml)
+          (message-forward-included-headers
+           (if (eq all-headers 'a)
+               nil
+             message-forward-included-headers)))
       (cond
        ((null arg))
        ((eq arg 1)
@@ -1380,11 +1388,11 @@ composing a new message."
           (forward-char 1))
         (widen)))))
 
-(defun gnus-summary-post-forward (&optional arg)
+(defun gnus-summary-post-forward (&optional arg all-headers)
   "Forward the current article to a newsgroup.
 See `gnus-summary-mail-forward' for ARG."
-  (interactive "P" gnus-summary-mode)
-  (gnus-summary-mail-forward arg t))
+  (interactive (gnus-interactive "P\ny") gnus-summary-mode)
+  (gnus-summary-mail-forward arg all-headers t))
 
 (defun gnus-summary-mail-crosspost-complaint (n)
   "Send a complaint about crossposting to the current article(s)."