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>

src/nvim/quickfix.c

@@ -2699,7 +2699,8 @@ static void qf_goto_win_with_qfl_file(int qf_fnum)
       // Didn't find it, go to the window before the quickfix
       // window, unless 'switchbuf' contains 'uselast': in this case we
       // try to jump to the previously used window first.
-      if ((swb_flags & SWB_USELAST) && win_valid(prevwin) && !prevwin->w_p_wfb) {
+      if ((swb_flags & SWB_USELAST) && win_valid(prevwin)
+          && !prevwin->w_p_wfb) {
         win = prevwin;
       } else if (altwin != NULL) {
         win = altwin;
@@ -2803,27 +2804,42 @@ static int qf_jump_edit_buffer(qf_info_T *qi, qfline_T *qf_ptr, int forceit, int
                      ECMD_HIDE + ECMD_SET_HELP,
                      prev_winid == curwin->handle ? curwin : NULL);
   } else {
-    if (!forceit && curwin->w_p_wfb) {
+    int fnum = qf_ptr->qf_fnum;
+
+    if (!forceit && curwin->w_p_wfb && curbuf->b_fnum != fnum) {
       if (qi->qfl_type == QFLT_LOCATION) {
         // Location lists cannot split or reassign their window
         // so 'winfixbuf' windows must fail
-        semsg("%s", e_winfixbuf_cannot_go_to_buffer);
-        return QF_ABORT;
+        emsg(_(e_winfixbuf_cannot_go_to_buffer));
+        return FAIL;
       }
 
-      if (!win_valid(prevwin)) {
-        // Split the window, which will be 'nowinfixbuf', and set curwin to that
-        exarg_T new_eap = {
-          .cmdidx = CMD_split,
-          .cmd = "split",
-          .arg = "",
-        };
-        ex_splitview(&new_eap);
+      if (win_valid(prevwin) && !prevwin->w_p_wfb
+          && !bt_quickfix(prevwin->w_buffer)) {
+        // 'winfixbuf' is set; attempt to change to a window without it
+        // that isn't a quickfix/location list window.
+        win_goto(prevwin);
+      }
+      if (curwin->w_p_wfb) {
+        // Split the window, which will be 'nowinfixbuf', and set curwin
+        // to that
+        if (win_split(0, 0) == OK) {
+          *opened_window = true;
+        }
+        if (curwin->w_p_wfb) {
+          // Autocommands set 'winfixbuf' or sent us to another window
+          // with it set.  Give up, but don't return immediately, as
+          // they may have messed with the list.
+          emsg(_(e_winfixbuf_cannot_go_to_buffer));
+          retval = FAIL;
+        }
       }
     }
 
-    retval = buflist_getfile(qf_ptr->qf_fnum, 1,
-                             GETF_SETMARK | GETF_SWITCH, forceit);
+    if (retval == OK) {
+      retval = buflist_getfile(fnum, 1,
+                               GETF_SETMARK | GETF_SWITCH, forceit);
+    }
   }
   // If a location list, check whether the associated window is still
   // present.