From 8a0dcf43305586853f452a77fa295b0c8d54b463 Mon Sep 17 00:00:00 2001
From: Bram Moolenaar <Bram@vim.org>
Date: Sun, 6 Sep 2020 15:14:45 +0200
Subject: patch 8.2.1621: crash when using submatch(0, 1) in substitute()

Problem:    Crash when using submatch(0, 1) in substitute().
Solution:   Increment reference count. (closes #6887)
---
 src/regexp.c                    | 1 +
 src/testdir/test_substitute.vim | 6 ++++++
 src/version.c                   | 2 ++
 3 files changed, 9 insertions(+)

diff --git a/src/regexp.c b/src/regexp.c
index 229f6ef2b..375731c3c 100644
--- a/src/regexp.c
+++ b/src/regexp.c
@@ -2543,6 +2543,7 @@ reg_submatch_list(int no)
 	list_free(list);
 	return NULL;
     }
+    ++list->lv_refcount;
     return list;
 }
 #endif
diff --git a/src/testdir/test_substitute.vim b/src/testdir/test_substitute.vim
index 61c9cb34e..a137aa527 100644
--- a/src/testdir/test_substitute.vim
+++ b/src/testdir/test_substitute.vim
@@ -881,6 +881,12 @@ func Test_invalid_submatch()
   call assert_equal([], submatch(1, 1))
 endfunc
 
+func Test_submatch_list_concatenate()
+  let pat = 'A\(.\)'
+  let Rep = {-> string([submatch(0, 1)] + [[submatch(1)]])}
+  call substitute('A1', pat, Rep, '')->assert_equal("[['A1'], ['1']]")
+endfunc
+
 func Test_substitute_expr_arg()
   call assert_equal('123456789-123456789=', substitute('123456789',
 	\ '\(.\)\(.\)\(.\)\(.\)\(.\)\(.\)\(.\)\(.\)\(.\)',
diff --git a/src/version.c b/src/version.c
index 36416ef17..cf7de76a6 100644
--- a/src/version.c
+++ b/src/version.c
@@ -754,6 +754,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1621,
 /**/
     1620,
 /**/
-- 
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