patch 8.0.0571: negative line number when using :z^ in an empty buffer commit https://github.com/vim/vim/commit/a364cdb648ae009fa7aa05382f5659335683d349 Author: Bram Moolenaar <Bram@vim.org> Date: Thu Apr 20 21:12:30 2017 +0200 patch 8.0.0571: negative line number when using :z^ in an empty buffer Problem: The cursor line number becomes negative when using :z^ in an empty buffer. (neovim https://github.com/vim/vim/issues/6557) Solution: Correct the line number. Also reset the column.

" Tests for the Tcl interface.

if !has('tcl')
  finish
end

function Test_tcldo()
  " Check deleting lines does not trigger ml_get error.
  new
  call setline(1, ['one', 'two', 'three'])
  tcldo ::vim::command %d_
  bwipe!

  " Check switching to another buffer does not trigger ml_get error.
  new
  let wincount = winnr('$')
  call setline(1, ['one', 'two', 'three'])
  tcldo ::vim::command new
  call assert_equal(wincount + 1, winnr('$'))
  bwipe!
  bwipe!
endfunc