From c312b8b87a589ed8452dbf0f555f05ff86d04692 Mon Sep 17 00:00:00 2001
From: Bram Moolenaar <Bram@vim.org>
Date: Sat, 28 Oct 2017 17:53:04 +0200
Subject: patch 8.0.1231: expanding file name drops dash

Problem:    Expanding file name drops dash. (stucki)
Solution:   Use the right position. (Christian Brabandt, closes #2184)
---
 src/ex_docmd.c               |  7 ++++++-
 src/testdir/test_cmdline.vim | 21 +++++++++++++++++++++
 src/version.c                |  2 ++
 3 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/src/ex_docmd.c b/src/ex_docmd.c
index 036569f76..547d1acdb 100644
--- a/src/ex_docmd.c
+++ b/src/ex_docmd.c
@@ -10715,9 +10715,12 @@ eval_vars(
 		if (*s == '<')		/* "#<99" uses v:oldfiles */
 		    ++s;
 		i = (int)getdigits(&s);
+		if (s == src + 2 && src[1] == '-')
+		    /* just a minus sign, don't skip over it */
+		    s--;
 		*usedlen = (int)(s - src); /* length of what we expand */
 
-		if (src[1] == '<')
+		if (src[1] == '<' && i != 0)
 		{
 		    if (*usedlen < 2)
 		    {
@@ -10740,6 +10743,8 @@ eval_vars(
 		}
 		else
 		{
+		    if (i == 0 && src[1] == '<' && *usedlen > 1)
+			*usedlen = 1;
 		    buf = buflist_findnr(i);
 		    if (buf == NULL)
 		    {
diff --git a/src/testdir/test_cmdline.vim b/src/testdir/test_cmdline.vim
index ff190821c..832413e81 100644
--- a/src/testdir/test_cmdline.vim
+++ b/src/testdir/test_cmdline.vim
@@ -365,6 +365,27 @@ func Test_cmdline_complete_user_cmd()
   delcommand Foo
 endfunc
 
+func Test_cmdline_write_alternatefile()
+  new
+  call setline('.', ['one', 'two'])
+  f foo.txt
+  new
+  f #-A
+  call assert_equal('foo.txt-A', expand('%'))
+  f #<-B.txt
+  call assert_equal('foo-B.txt', expand('%'))
+  f %<
+  call assert_equal('foo-B', expand('%'))
+  new
+  call assert_fails('f #<', 'E95')
+  bw!
+  f foo-B.txt
+  f %<-A
+  call assert_equal('foo-B-A', expand('%'))
+  bw!
+  bw!
+endfunc
+
 " using a leading backslash here
 set cpo+=C
 
diff --git a/src/version.c b/src/version.c
index 221c7576a..4ce6fee68 100644
--- a/src/version.c
+++ b/src/version.c
@@ -761,6 +761,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1231,
 /**/
     1230,
 /**/
-- 
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