fix(startup): trigger UIEnter for the correct channel (#25860)

src/nvim/autocmd.c

@@ -2570,6 +2570,9 @@ void do_autocmd_uienter(uint64_t chanid, bool attached)
 {
   static bool recursive = false;
 
+  if (starting == NO_SCREEN) {
+    return;  // user config hasn't been sourced yet
+  }
   if (recursive) {
     return;  // disallow recursion
   }

src/nvim/main.c

@@ -589,7 +589,7 @@ int main(int argc, char **argv)
   apply_autocmds(EVENT_VIMENTER, NULL, NULL, false, curbuf);
   TIME_MSG("VimEnter autocommands");
   if (use_remote_ui) {
-    do_autocmd_uienter(CHAN_STDIO, true);
+    do_autocmd_uienter_all();
     TIME_MSG("UIEnter autocommands");
   }
 

src/nvim/ui.c

@@ -337,6 +337,16 @@ void vim_beep(unsigned val)
   }
 }
 
+/// Trigger UIEnter for all attached UIs.
+/// Used on startup after VimEnter.
+void do_autocmd_uienter_all(void)
+{
+  for (size_t i = 0; i < ui_count; i++) {
+    UIData *data = uis[i]->data;
+    do_autocmd_uienter(data->channel_id, true);
+  }
+}
+
 void ui_attach_impl(UI *ui, uint64_t chanid)
 {
   if (ui_count == MAX_UI_COUNT) {

test/functional/api/ui_spec.lua

@@ -60,14 +60,13 @@ describe('nvim_ui_attach()', function()
 end)
 
 it('autocmds UIEnter/UILeave', function()
-  clear{
+  clear{args_rm={'--headless'}}
-    args_rm={'--headless'},
+  exec([[
-    args={
+    let g:evs = []
-      '--cmd', 'let g:evs = []',
+    autocmd UIEnter * call add(g:evs, "UIEnter") | let g:uienter_ev = deepcopy(v:event)
-      '--cmd', 'autocmd UIEnter * :call add(g:evs, "UIEnter") | let g:uienter_ev = deepcopy(v:event)',
+    autocmd UILeave * call add(g:evs, "UILeave") | let g:uileave_ev = deepcopy(v:event)
-      '--cmd', 'autocmd UILeave * :call add(g:evs, "UILeave") | let g:uileave_ev = deepcopy(v:event)',
+    autocmd VimEnter * call add(g:evs, "VimEnter")
-      '--cmd', 'autocmd VimEnter * :call add(g:evs, "VimEnter")',
+  ]])
-    }}
   local screen = Screen.new()
   screen:attach()
   eq({chan=1}, eval('g:uienter_ev'))

test/functional/ui/embed_spec.lua

@@ -159,19 +159,21 @@ describe('--embed --listen UI', function()
 
     local child_session = helpers.connect(child_server)
 
-    local info_ok, apiinfo = child_session:request('nvim_get_api_info')
+    local info_ok, api_info = child_session:request('nvim_get_api_info')
-    assert(info_ok)
+    ok(info_ok)
-    assert(#apiinfo == 2)
+    eq(2, #api_info)
+    ok(api_info[1] > 2, 'channel_id > 2', api_info[1])
 
     child_session:request('nvim_exec2', [[
-      let g:vim_entered=0
+      let g:evs = []
-      autocmd VimEnter * call execute("let g:vim_entered=1")
+      autocmd UIEnter * call add(g:evs, $"UIEnter:{v:event.chan}")
+      autocmd VimEnter * call add(g:evs, "VimEnter")
     ]], {})
 
-    -- g:vim_entered shouldn't be set to 1 until after attach
+    -- VimEnter and UIEnter shouldn't be triggered until after attach
-    local var_ok, var = child_session:request('nvim_get_var', 'vim_entered')
+    local var_ok, var = child_session:request('nvim_get_var', 'evs')
-    assert(var_ok)
+    ok(var_ok)
-    ok(var == 0)
+    eq({}, var)
 
     local child_screen = Screen.new(40, 6)
     child_screen:attach(nil, child_session)
@@ -186,10 +188,9 @@ describe('--embed --listen UI', function()
       [1] = {foreground = Screen.colors.Blue, bold = true};
     }}
 
-    -- g:vim_entered should now be set to 1
+    -- VimEnter and UIEnter should now be triggered
-    var_ok, var = child_session:request('nvim_get_var', 'vim_entered')
+    var_ok, var = child_session:request('nvim_get_var', 'evs')
-    assert(var_ok)
+    ok(var_ok)
-    ok(var == 1)
+    eq({'VimEnter', ('UIEnter:%d'):format(api_info[1])}, var)
-
   end)
 end)