[RDY] Add buffer information to tabline_update (#12481)

* Add buffer information to tabline_update

Most terminal implementations of the tabline display buffer and tab
information. Many neovim-qt users disable GuiTabline because it lacks
functionality provided in the terminal implementation.

The tabline_update event should include buffer information too, so client GUIs
can display rich useful tabs.

2 files changed, 20 insertions, 2 deletions

diff --git a/src/nvim/api/ui_events.in.h b/src/nvim/api/ui_events.in.h
index 11e21a88ea..35d39a34d7 100644
--- a/src/nvim/api/ui_events.in.h
+++ b/src/nvim/api/ui_events.in.h
@@ -130,7 +130,8 @@ void popupmenu_hide(void)
 void popupmenu_select(Integer selected)
   FUNC_API_SINCE(3) FUNC_API_REMOTE_ONLY;
 
-void tabline_update(Tabpage current, Array tabs)
+void tabline_update(Tabpage current, Array tabs,
+                    Buffer current_buffer, Array buffers)
   FUNC_API_SINCE(3) FUNC_API_REMOTE_ONLY;
 
 void cmdline_show(Array content, Integer pos, String firstc, String prompt,
diff --git a/src/nvim/screen.c b/src/nvim/screen.c
index 04157a0154..3446a944cd 100644
--- a/src/nvim/screen.c
+++ b/src/nvim/screen.c
@@ -7211,7 +7211,24 @@ void ui_ext_tabline_update(void)
 
     ADD(tabs, DICTIONARY_OBJ(tab_info));
   }
-  ui_call_tabline_update(curtab->handle, tabs);
+
+  Array buffers = ARRAY_DICT_INIT;
+  FOR_ALL_BUFFERS(buf) {
+    // Do not include unlisted buffers
+    if (!buf->b_p_bl) {
+      continue;
+    }
+
+    Dictionary buffer_info = ARRAY_DICT_INIT;
+    PUT(buffer_info, "buffer", BUFFER_OBJ(buf->handle));
+
+    get_trans_bufname(buf);
+    PUT(buffer_info, "name", STRING_OBJ(cstr_to_string((char *)NameBuff)));
+
+    ADD(buffers, DICTIONARY_OBJ(buffer_info));
+  }
+
+  ui_call_tabline_update(curtab->handle, tabs, curbuf->handle, buffers);
 }
 
 /*