commit https://github.com/vim/vim/commit/4f416e41243ca151b95d39d81ce23d00b1484755 Author: Bram Moolenaar <Bram@vim.org> Date: Tue Aug 16 16:08:18 2016 +0200 patch 7.4.2217 Problem: When using matchaddpos() a character after the end of the line can be highlighted. Solution: Only highlight existing characters. (Hirohito Higashi)

" Tests for Visual mode.  Uses double-wide character.
if !has('multi_byte')
  finish
endif

if !has('visual')
  finish
endif

func Test_block_shift_multibyte()
  split
  call setline(1, ['xヹxxx', 'ヹxxx'])
  exe "normal 1G0l\<C-V>jl>"
  call assert_equal('x	 ヹxxx', getline(1))
  call assert_equal('	ヹxxx', getline(2))
  q!
endfunc