dictwatcheradd(): support b:changedtick #9693

fixes #6635
closes #9693

2 files changed, 29 insertions, 1 deletions

diff --git a/src/nvim/buffer.h b/src/nvim/buffer.h
index 64c906fc96..ee3fda5f6d 100644
--- a/src/nvim/buffer.h
+++ b/src/nvim/buffer.h
@@ -74,6 +74,8 @@ static inline void buf_set_changedtick(buf_T *const buf,
 static inline void buf_set_changedtick(buf_T *const buf,
                                        const varnumber_T changedtick)
 {
+  typval_T old_val = buf->changedtick_di.di_tv;
+
 #ifndef NDEBUG
   dictitem_T *const changedtick_di = tv_dict_find(
       buf->b_vars, S_LEN("changedtick"));
@@ -87,6 +89,13 @@ static inline void buf_set_changedtick(buf_T *const buf,
   assert(changedtick_di == (dictitem_T *)&buf->changedtick_di);
 #endif
   buf->changedtick_di.di_tv.vval.v_number = changedtick;
+
+  if (tv_dict_is_watched(buf->b_vars)) {
+    tv_dict_watcher_notify(buf->b_vars,
+                           (char *)buf->changedtick_di.di_key,
+                           &buf->changedtick_di.di_tv,
+                           &old_val);
+  }
 }
 
 static inline varnumber_T buf_get_changedtick(const buf_T *const buf)
diff --git a/test/functional/ex_cmds/dict_notifications_spec.lua b/test/functional/ex_cmds/dict_notifications_spec.lua
index 3d550588e7..48e7e05e4c 100644
--- a/test/functional/ex_cmds/dict_notifications_spec.lua
+++ b/test/functional/ex_cmds/dict_notifications_spec.lua
@@ -1,12 +1,13 @@
 local helpers = require('test.functional.helpers')(after_each)
 local clear, nvim, source = helpers.clear, helpers.nvim, helpers.source
+local insert = helpers.insert
 local eq, next_msg = helpers.eq, helpers.next_msg
 local exc_exec = helpers.exc_exec
 local command = helpers.command
 local eval = helpers.eval
 
 
-describe('dictionary change notifications', function()
+describe('VimL dictionary notifications', function()
   local channel
 
   before_each(function()
@@ -338,4 +339,22 @@ describe('dictionary change notifications', function()
       eq({'notification', '2', {'foo', {old = 'baz', new = 'bar'}}}, next_msg())
     end)
   end)
+
+  it('for b:changedtick', function()
+    source([[
+      function! OnTickChanged(dict, key, value)
+        call rpcnotify(g:channel, 'SendChangeTick', a:key, a:value)
+      endfunction
+      call dictwatcheradd(b:, 'changedtick', 'OnTickChanged')
+    ]])
+
+    insert('t');
+    eq({'notification', 'SendChangeTick', {'changedtick', {old = 2, new = 3}}},
+       next_msg())
+
+    command([[call dictwatcherdel(b:, 'changedtick', 'OnTickChanged')]])
+    insert('t');
+    eq(2, eval('1+1')) -- Still alive?
+  end)
+
 end)