From 888f758e9599f619c745f8c93089225e46c6aac2 Mon Sep 17 00:00:00 2001
From: Serge Gebhardt <serge.gebhardt@gmail.com>
Date: Sat, 19 Nov 2016 23:15:21 +0100
Subject: [PATCH] $forward_references includes References: header on forwards

By default a forwarded message does not reference the messages it
contains. This commit introduces a new boolean option
`$forward_references`. When it is set, a forwarded message includes the
`In-Reply-To:` and `References:` headers, just like a reply would. Hence
the forwarded message becomes part of the original thread instead of
starting a new one.
---
 doc/manual.xml.head | 9 +++++++++
 init.h              | 8 ++++++++
 mutt.h              | 1 +
 send.c              | 4 ++++
 4 files changed, 22 insertions(+)

diff --git a/doc/manual.xml.head b/doc/manual.xml.head
index f4f1e5d..7ce5144 100644
--- a/doc/manual.xml.head
+++ b/doc/manual.xml.head
@@ -2286,6 +2286,15 @@ linkend="mime-forward">$mime_forward</link> is set.
 </para>
 
 <para>
+By default a forwarded message does not reference the messages it
+contains. When <link linkend="forward-references">$forward_references</link>
+is set, a forwarded message includes the <quote>In-Reply-To:</quote>
+and <quote>References:</quote> headers, just like a reply would. Hence
+the forwarded message becomes part of the original thread instead of
+starting a new one.
+</para>
+
+<para>
 Editing the message to forward follows the same procedure as sending or
 replying to a message does.
 </para>
diff --git a/init.h b/init.h
index 3a9b078..bf5c383 100644
--- a/init.h
+++ b/init.h
@@ -982,6 +982,14 @@ struct option_t MuttVars[] = {
   { "forw_quote",	DT_SYN,  R_NONE, UL "forward_quote", 0 },
   /*
   */
+  { "forward_references", DT_BOOL, R_NONE, OPTFORWREF, 0 },
+  /*
+  ** .pp
+  ** When \fIset\fP, forwarded messages set the ``In-Reply-To:'' and
+  ** ``References:'' headers in the same way as normal replies would. Hence the
+  ** forwarded message becomes part of the original thread instead of starting
+  ** a new one.
+  */
   { "from",		DT_ADDR, R_NONE, UL &From, UL 0 },
   /*
   ** .pp
diff --git a/mutt.h b/mutt.h
index 0fe027f..94291c1 100644
--- a/mutt.h
+++ b/mutt.h
@@ -399,6 +399,7 @@ enum
   OPTFORCENAME,
   OPTFORWDECODE,
   OPTFORWQUOTE,
+  OPTFORWREF,
 #ifdef USE_HCACHE
   OPTHCACHEVERIFY,
 #if defined(HAVE_QDBM) || defined(HAVE_TC) || defined(HAVE_KC)
diff --git a/send.c b/send.c
index d2a2491..bb468f7 100644
--- a/send.c
+++ b/send.c
@@ -810,7 +810,11 @@ envelope_defaults (ENVELOPE *env, CONTEXT *ctx, HEADER *cur, int flags)
     mutt_make_reference_headers (tag ? NULL : curenv, env, ctx);
   }
   else if (flags & SENDFORWARD)
+  {
     mutt_make_forward_subject (env, ctx, cur);
+    if (option (OPTFORWREF))
+      mutt_make_reference_headers (tag ? NULL : curenv, env, ctx);
+  }
 
   return (0);
 }