4 files changed, 157 insertions, 37 deletions

diff --git a/src/nvim/ex_cmds2.c b/src/nvim/ex_cmds2.c
index 3120868350..dacdb27b08 100644
--- a/src/nvim/ex_cmds2.c
+++ b/src/nvim/ex_cmds2.c
@@ -447,21 +447,24 @@ void ex_listdo(exarg_T *eap)
   if (curwin->w_p_wfb) {
     if ((eap->cmdidx == CMD_ldo || eap->cmdidx == CMD_lfdo) && !eap->forceit) {
       // Disallow :ldo if 'winfixbuf' is applied
-      semsg("%s", e_winfixbuf_cannot_go_to_buffer);
+      emsg(_(e_winfixbuf_cannot_go_to_buffer));
       return;
     }
 
-    if (win_valid(prevwin)) {
-      // Change the current window to another because 'winfixbuf' is enabled
-      curwin = prevwin;
-    } else {
+    if (win_valid(prevwin) && !prevwin->w_p_wfb) {
+      // 'winfixbuf' is set; attempt to change to a window without it.
+      win_goto(prevwin);
+    }
+    if (curwin->w_p_wfb) {
       // 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);
+      win_split(0, 0);
+
+      if (curwin->w_p_wfb) {
+        // Autocommands set 'winfixbuf' or sent us to another window
+        // with it set. Give up.
+        emsg(_(e_winfixbuf_cannot_go_to_buffer));
+        return;
+      }
     }
   }
 
diff --git a/src/nvim/quickfix.c b/src/nvim/quickfix.c
index 3dd4e35f65..28691914bb 100644
--- a/src/nvim/quickfix.c
+++ b/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.
diff --git a/src/nvim/window.c b/src/nvim/window.c
index 9f84713ee7..521699f2f0 100644
--- a/src/nvim/window.c
+++ b/src/nvim/window.c
@@ -139,7 +139,7 @@ static void log_frame_layout(frame_T *frame)
 bool check_can_set_curbuf_disabled(void)
 {
   if (curwin->w_p_wfb) {
-    semsg("%s", e_winfixbuf_cannot_go_to_buffer);
+    emsg(_(e_winfixbuf_cannot_go_to_buffer));
     return false;
   }
 
@@ -155,7 +155,7 @@ bool check_can_set_curbuf_disabled(void)
 bool check_can_set_curbuf_forceit(int forceit)
 {
   if (!forceit && curwin->w_p_wfb) {
-    semsg("%s", e_winfixbuf_cannot_go_to_buffer);
+    emsg(_(e_winfixbuf_cannot_go_to_buffer));
     return false;
   }
 
diff --git a/test/old/testdir/test_winfixbuf.vim b/test/old/testdir/test_winfixbuf.vim
index 5412fecd07..eb6d35f0af 100644
--- a/test/old/testdir/test_winfixbuf.vim
+++ b/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()
+  call assert_equal(1, getloclist(0, #{idx: 0}).idx)
+
   lnext!
+  call assert_equal(2, getloclist(0, #{idx: 0}).idx)
+  call assert_equal(l:middle, bufnr())
 
   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!  " Reset for the next test
+  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()
+  call assert_equal(1, getloclist(0, #{idx: 0}).idx)
+
   lnext!
+  call assert_equal(2, getloclist(0, #{idx: 0}).idx)
+  call assert_equal(l:current, bufnr())
 
   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!  " Reset for the next test
+  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()
+  call assert_equal(1, getloclist(0, #{idx: 0}).idx)
+
   lnext!
+  call assert_equal(2, getloclist(0, #{idx: 0}).idx)
+  call assert_equal(l:current, bufnr())
 
   call assert_fails("lnfile", "E1513:")
+  call assert_equal(2, getloclist(0, #{idx: 0}).idx)
   call assert_equal(l:current, bufnr())
 
-  lprevious!  " Reset for the next test call
-
   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()
+  call assert_equal(1, getloclist(0, #{idx: 0}).idx)
+
   lnext!
+  call assert_equal(2, getloclist(0, #{idx: 0}).idx)
+  call assert_equal(l:middle, bufnr())
 
   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())
 
-  lnext!  " Reset for the next test call
-
   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