vim-patch:9.1.0150: Several minor 'winfixbuf' issues

Problem:  several minor 'winfixbuf' issues exist, mostly relating to the
          quickfix list
Solution: address them and adjust tests. Retab and reflow a few things too.
          (Sean Dewar)

Things touched include:

- Replace the semsgs with gettext'd emsgs.

- Handle window switching in ex_listdo properly, so curbuf and curwin
  are kept in-sync and trigger autocommands; handle those properly.

- Don't change the list entry index in qf_jump_edit_buffer if we fail
  due to 'wfb' (achieved by returning FAIL; QF_ABORT should only be used
  if the list was changed).

- Make qf_jump_edit_buffer actually switch to prevwin when using `:cXX`
  commands **outside** of the list window if 'wfb' is set in curwin.
  Handle autocommands properly in case they mess with the list.

  NOTE: previously, it seemed to split if 'wfb' was set, but do nothing
  and fail if prevwin is *valid*. This behaviour seemed strange, and maybe
  unintentional? Now it aligns more with what's described for the `:cXX`
  commands in the original PR description when used outside a list window,
  I think.

- In both functions, only consider prevwin if 'wfb' isn't set for it;
  fallback to splitting otherwise.

- Use win_split to split. Not sure if there was a specific reason for
  using ex_splitview. win_split is simpler and respects modifiers like
  :vertical that may have been used. Plus, its return value can be checked
  for setting opened_window in qf code (technically win_split_ins autocmds
  could immediately close it or change windows, in which the qf code might
  close some other window on failure; it's already the case elsewhere,
  though).

closes: vim/vim#14142

4bb505e28c

Co-authored-by: Sean Dewar <6256228+seandewar@users.noreply.github.com>

test/old/testdir/test_winfixbuf.vim

@@ -1254,14 +1254,27 @@ func Test_lNext()
   call s:reset_all_buffers()
 
   let [l:first, l:middle, _] = s:make_simple_location_list()
-  lnext!
+  call assert_equal(1, getloclist(0, #{idx: 0}).idx)
 
-  call assert_fails("lNext", "E1513:")
+  lnext!
+  call assert_equal(2, getloclist(0, #{idx: 0}).idx)
   call assert_equal(l:middle, bufnr())
 
-  lnext!  " Reset for the next test
+  call assert_fails("lNext", "E1513:")
+  " Ensure the entry didn't change.
+  call assert_equal(2, getloclist(0, #{idx: 0}).idx)
+  call assert_equal(l:middle, bufnr())
+
+  lnext!
+  call assert_equal(3, getloclist(0, #{idx: 0}).idx)
+  call assert_equal(l:middle, bufnr())
 
   lNext!
+  call assert_equal(2, getloclist(0, #{idx: 0}).idx)
+  call assert_equal(l:middle, bufnr())
+
+  lNext!
+  call assert_equal(1, getloclist(0, #{idx: 0}).idx)
   call assert_equal(l:first, bufnr())
 endfunc
 
@@ -1271,14 +1284,23 @@ func Test_lNfile()
   call s:reset_all_buffers()
 
   let [l:first, l:current, _] = s:make_simple_location_list()
-  lnext!
+  call assert_equal(1, getloclist(0, #{idx: 0}).idx)
 
-  call assert_fails("lNfile", "E1513:")
+  lnext!
+  call assert_equal(2, getloclist(0, #{idx: 0}).idx)
   call assert_equal(l:current, bufnr())
 
-  lnext!  " Reset for the next test
+  call assert_fails("lNfile", "E1513:")
+  " Ensure the entry didn't change.
+  call assert_equal(2, getloclist(0, #{idx: 0}).idx)
+  call assert_equal(l:current, bufnr())
+
+  lnext!
+  call assert_equal(3, getloclist(0, #{idx: 0}).idx)
+  call assert_equal(l:current, bufnr())
 
   lNfile!
+  call assert_equal(1, getloclist(0, #{idx: 0}).idx)
   call assert_equal(l:first, bufnr())
 endfunc
 
@@ -1485,14 +1507,18 @@ func Test_lnfile()
   call s:reset_all_buffers()
 
   let [_, l:current, l:last] = s:make_simple_location_list()
-  lnext!
+  call assert_equal(1, getloclist(0, #{idx: 0}).idx)
 
-  call assert_fails("lnfile", "E1513:")
+  lnext!
+  call assert_equal(2, getloclist(0, #{idx: 0}).idx)
   call assert_equal(l:current, bufnr())
 
-  lprevious!  " Reset for the next test call
+  call assert_fails("lnfile", "E1513:")
+  call assert_equal(2, getloclist(0, #{idx: 0}).idx)
+  call assert_equal(l:current, bufnr())
 
   lnfile!
+  call assert_equal(4, getloclist(0, #{idx: 0}).idx)
   call assert_equal(l:last, bufnr())
 endfunc
 
@@ -1519,14 +1545,19 @@ func Test_lprevious()
   call s:reset_all_buffers()
 
   let [l:first, l:middle, _] = s:make_simple_location_list()
-  lnext!
+  call assert_equal(1, getloclist(0, #{idx: 0}).idx)
 
-  call assert_fails("lprevious", "E1513:")
+  lnext!
+  call assert_equal(2, getloclist(0, #{idx: 0}).idx)
   call assert_equal(l:middle, bufnr())
 
-  lnext!  " Reset for the next test call
+  call assert_fails("lprevious", "E1513:")
+  " Ensure the entry didn't change.
+  call assert_equal(2, getloclist(0, #{idx: 0}).idx)
+  call assert_equal(l:middle, bufnr())
 
   lprevious!
+  call assert_equal(1, getloclist(0, #{idx: 0}).idx)
   call assert_equal(l:first, bufnr())
 endfunc
 
@@ -3134,17 +3165,87 @@ endfunc
 func Test_quickfix_switchbuf_invalid_prevwin()
   call s:reset_all_buffers()
 
-  let [l:first, _] = s:make_simple_quickfix()
-  call assert_notequal(l:first, bufnr())
-  call assert_equal(1, winnr('$'))
+  call s:make_simple_quickfix()
+  call assert_equal(1, getqflist(#{idx: 0}).idx)
 
   set switchbuf=uselast
   split
   copen
   execute winnr('#') 'quit'
+  call assert_equal(2, winnr('$'))
+
+  cnext  " Would've triggered a null pointer member access
+  call assert_equal(2, getqflist(#{idx: 0}).idx)
 
-  call assert_fails('cfirst', 'E1513:')
   set switchbuf&
 endfunc
 
+func Test_listdo_goto_prevwin()
+  call s:reset_all_buffers()
+  call s:make_buffers_list()
+
+  new
+  call assert_equal(0, &winfixbuf)
+  wincmd p
+  call assert_equal(1, &winfixbuf)
+  call assert_notequal(bufnr(), bufnr('#'))
+
+  augroup ListDoGotoPrevwin
+    au!
+    au BufLeave * let s:triggered = 1
+          \| call assert_equal(bufnr(), winbufnr(winnr()))
+  augroup END
+  " Should correctly switch to the window without 'winfixbuf', and curbuf should
+  " be consistent with curwin->w_buffer for autocommands.
+  bufdo "
+  call assert_equal(0, &winfixbuf)
+  call assert_equal(1, s:triggered)
+  unlet! s:triggered
+  au! ListDoGotoPrevwin
+
+  set winfixbuf
+  wincmd p
+  call assert_equal(2, winnr('$'))
+  " Both curwin and prevwin have 'winfixbuf' set, so should split a new window
+  " without it set.
+  bufdo "
+  call assert_equal(0, &winfixbuf)
+  call assert_equal(3, winnr('$'))
+
+  quit
+  call assert_equal(2, winnr('$'))
+  call assert_equal(1, &winfixbuf)
+  augroup ListDoGotoPrevwin
+    au!
+    au WinEnter * ++once set winfixbuf
+  augroup END
+  " Same as before, but naughty autocommands set 'winfixbuf' for the new window.
+  " :bufdo should give up in this case.
+  call assert_fails('bufdo "', 'E1513:')
+
+  au! ListDoGotoPrevwin
+  augroup! ListDoGotoPrevwin
+endfunc
+
+func Test_quickfix_changed_split_failed()
+  call s:reset_all_buffers()
+
+  call s:make_simple_quickfix()
+  call assert_equal(1, winnr('$'))
+
+  " Quickfix code will open a split in an attempt to get a 'nowinfixbuf' window
+  " to switch buffers in.  Interfere with things by setting 'winfixbuf' in it.
+  augroup QfChanged
+    au!
+    au WinEnter * ++once call assert_equal(2, winnr('$'))
+          \| set winfixbuf | call setqflist([], 'f')
+  augroup END
+  call assert_fails('cnext', ['E1513:', 'E925:'])
+  " Check that the split was automatically closed.
+  call assert_equal(1, winnr('$'))
+
+  au! QfChanged
+  augroup! QfChanged
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab