# HG changeset patch
# User Bram Moolenaar <Bram@vim.org>
# Date 1655558104 -7200
# Node ID b8dc0a76911efa8d5142f03fb4e9318d002c4e0d
# Parent  d0bec8ebee71ebe243ddfa0d39f1ff8121bc0935
patch 8.2.5123: using invalid index when looking for spell suggestions

Commit: https://github.com/vim/vim/commit/156d3911952d73b03d7420dc3540215247db0fe8
Author: Bram Moolenaar <Bram@vim.org>
Date:   Sat Jun 18 14:09:08 2022 +0100

    patch 8.2.5123: using invalid index when looking for spell suggestions

    Problem:    Using invalid index when looking for spell suggestions.
    Solution:   Do not decrement the index when it is zero.

diff --git a/src/spellsuggest.c b/src/spellsuggest.c
--- a/src/spellsuggest.c
+++ b/src/spellsuggest.c
@@ -1973,7 +1973,8 @@ suggest_trie_walk(
 			    sp->ts_isdiff = (newscore != 0)
 						       ? DIFF_YES : DIFF_NONE;
 			}
-			else if (sp->ts_isdiff == DIFF_INSERT)
+			else if (sp->ts_isdiff == DIFF_INSERT
+							    && sp->ts_fidx > 0)
 			    // When inserting trail bytes don't advance in the
 			    // bad word.
 			    --sp->ts_fidx;
diff --git a/src/testdir/test_spell.vim b/src/testdir/test_spell.vim
--- a/src/testdir/test_spell.vim
+++ b/src/testdir/test_spell.vim
@@ -70,6 +70,16 @@ func Test_z_equal_on_invalid_utf8_word()
   bwipe!
 endfunc
 
+func Test_z_equal_on_single_character()
+  " this was decrementing the index below zero
+  new
+  norm a0\Ê
+  norm zW
+  norm z=
+
+  bwipe!
+endfunc
+
 " Test spellbadword() with argument
 func Test_spellbadword()
   set spell
diff --git a/src/version.c b/src/version.c
--- a/src/version.c
+++ b/src/version.c
@@ -735,6 +735,8 @@ static char *(features[]) =
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    5123,
+/**/
     5122,
 /**/
     5121,