patch 8.0.0552: toupper and tolower don't work properly for Turkish commit https://github.com/vim/vim/commit/3317d5ebbe8304da82b8088446060afcae0012af Author: Bram Moolenaar <Bram@vim.org> Date: Sat Apr 8 19:12:06 2017 +0200 patch 8.0.0552: toupper and tolower don't work properly for Turkish Problem: Toupper and tolower don't work properly for Turkish when 'casemap' is empty. (Bjorn Linse) Solution: Check the 'casemap' options when deciding how to upper/lower case.

Test for search('multi-byte char', 'bce')

STARTTEST
:source small.vim
:source mbyte.vim
:set encoding=utf-8
:/^Test bce:/+1
:$put =search('Ａ', 'bce', line('.'))
:1;/^Results:/,$wq! test.out
ENDTEST

Results:

Test bce:
Ａ