vim-patch:8.0.0536: quickfix window not updated when freeing quickfix stack

Problem:    Quickfix window not updated when freeing quickfix stack.
Solution:   Update the quickfix window. (Yegappan Lakshmanan)

69f40be645

src/nvim/quickfix.c

@@ -4267,13 +4267,57 @@ static int qf_set_properties(qf_info_T *qi, dict_T *what, int action)
   return retval;
 }
 
+// Find the non-location list window with the specified location list.
+static win_T * find_win_with_ll(qf_info_T *qi)
+{
+  FOR_ALL_WINDOWS_IN_TAB(wp, curtab) {
+    if ((wp->w_llist == qi) && !bt_quickfix(wp->w_buffer)) {
+      return wp;
+    }
+  }
+
+  return NULL;
+}
+
+// Free the entire quickfix/location list stack.
+// If the quickfix/location list window is open, then clear it.
 static void qf_free_stack(win_T *wp, qf_info_T *qi)
 {
+  win_T *qfwin = qf_find_win(qi);
+
+  if (qfwin != NULL) {
+    // If the quickfix/location list window is open, then clear it
+    if (qi->qf_curlist < qi->qf_listcount) {
+      qf_free(qi, qi->qf_curlist);
+    }
+    qf_update_buffer(qi, NULL);
+  }
+
+  win_T *llwin = NULL;
+  win_T *orig_wp = wp;
+  if (wp != NULL && IS_LL_WINDOW(wp)) {
+    // If in the location list window, then use the non-location list
+    // window with this location list (if present)
+    llwin = find_win_with_ll(qi);
+    if (llwin != NULL) {
+      wp = llwin;
+    }
+  }
+
   qf_free_all(wp);
   if (wp == NULL) {
     // quickfix list
     qi->qf_curlist = 0;
     qi->qf_listcount = 0;
+  } else if (IS_LL_WINDOW(orig_wp)) {
+    // If the location list window is open, then create a new empty location
+    // list
+    qf_info_T *new_ll = ll_new_list();
+    orig_wp->w_llist_ref = new_ll;
+    if (llwin != NULL) {
+      llwin->w_llist = new_ll;
+      new_ll->qf_refcount++;
+    }
   }
 }
 

src/nvim/testdir/test_quickfix.vim

@@ -1894,3 +1894,66 @@ func Test_vimgrep()
   call XvimgrepTests('c')
   call XvimgrepTests('l')
 endfunc
+
+func XfreeTests(cchar)
+  call s:setup_commands(a:cchar)
+
+  enew | only
+
+  " Deleting the quickfix stack should work even When the current list is
+  " somewhere in the middle of the stack
+  Xexpr ['Xfile1:10:10:Line 10', 'Xfile1:15:15:Line 15']
+  Xexpr ['Xfile2:20:20:Line 20', 'Xfile2:25:25:Line 25']
+  Xexpr ['Xfile3:30:30:Line 30', 'Xfile3:35:35:Line 35']
+  Xolder
+  call g:Xsetlist([], 'f')
+  call assert_equal(0, len(g:Xgetlist()))
+
+  " After deleting the stack, adding a new list should create a stack with a
+  " single list.
+  Xexpr ['Xfile1:10:10:Line 10', 'Xfile1:15:15:Line 15']
+  call assert_equal(1, g:Xgetlist({'all':1}).nr)
+
+  " Deleting the stack from a quickfix window should update/clear the
+  " quickfix/location list window.
+  Xexpr ['Xfile1:10:10:Line 10', 'Xfile1:15:15:Line 15']
+  Xexpr ['Xfile2:20:20:Line 20', 'Xfile2:25:25:Line 25']
+  Xexpr ['Xfile3:30:30:Line 30', 'Xfile3:35:35:Line 35']
+  Xolder
+  Xwindow
+  call g:Xsetlist([], 'f')
+  call assert_equal(2, winnr('$'))
+  call assert_equal(1, line('$'))
+  Xclose
+
+  " Deleting the stack from a non-quickfix window should update/clear the
+  " quickfix/location list window.
+  Xexpr ['Xfile1:10:10:Line 10', 'Xfile1:15:15:Line 15']
+  Xexpr ['Xfile2:20:20:Line 20', 'Xfile2:25:25:Line 25']
+  Xexpr ['Xfile3:30:30:Line 30', 'Xfile3:35:35:Line 35']
+  Xolder
+  Xwindow
+  wincmd p
+  call g:Xsetlist([], 'f')
+  call assert_equal(0, len(g:Xgetlist()))
+  wincmd p
+  call assert_equal(2, winnr('$'))
+  call assert_equal(1, line('$'))
+
+  " After deleting the location list stack, if the location list window is
+  " opened, then a new location list should be created. So opening the
+  " location list window again should not create a new window.
+  if a:cchar == 'l'
+      lexpr ['Xfile1:10:10:Line 10', 'Xfile1:15:15:Line 15']
+      wincmd p
+      lopen
+      call assert_equal(2, winnr('$'))
+  endif
+  Xclose
+endfunc
+
+" Tests for the quickifx free functionality
+func Test_qf_free()
+  call XfreeTests('c')
+  call XfreeTests('l')
+endfunc