commit 5b276aa80e112ae1993bd43e28f599f257827c54
author Bram Moolenaar <Bram@vim.org> Sat Apr 22 23:49:52 2017 +0200
committer Bram Moolenaar <Bram@vim.org> Sat Apr 22 23:49:52 2017 +0200
tree eeab3f5b2d7834c7755e1cc74e3245567308714e
parent 94be619e30e82d28cadeea5e0766c6f5c321ff8b

patch 8.0.0582: illegal memory access with z= command

Problem:    Illegal memory access with z= command. (Dominique Pelle)
Solution:   Avoid case folded text to be longer than the original text.  Use
            MB_PTR2LEN() instead of MB_BYTE2LEN().

src/testdir/test_spell.vim

diff --git a/src/testdir/test_spell.vim b/src/testdir/test_spell.vim
index e6c3729..0688d61 100644
--- a/src/testdir/test_spell.vim
+++ b/src/testdir/test_spell.vim
@@ -18,3 +18,12 @@
   bwipe!
   set nospell
 endfunc
+
+func Test_z_equal_on_invalid_utf8_word()
+  split
+  set spell
+  call setline(1, "\xff")
+  norm z=
+  set nospell
+  bwipe!
+endfunc