fix: avoid overlapping signature window with popupmenu

Thanks @soifou!

Author: Saghen

lua/blink/cmp/signature/trigger.lua

@@ -80,7 +80,7 @@ function trigger.activate()
       end
     end,
     on_insert_leave = function() trigger.hide() end,
-    on_complete_changed = function() end,
+    on_complete_changed = function() require('blink.cmp.signature.window').update_position() end,
   })
 
   if config.show_on_accept then

lua/blink/cmp/signature/window.lua

@@ -130,6 +130,14 @@ function signature.update_position()
     direction_priority = menu_win_is_up and { 's' } or { 'n' }
   end
 
+  -- same for popupmenu, we want to place the signature window on the opposite side
+  local popupmenu_pos = vim.fn.pum_getpos()
+  if popupmenu_pos.row ~= nil then
+    local cursor_screen_row = vim.fn.winline()
+    local popupmenu_is_up = popupmenu_pos.row - cursor_screen_row < 0
+    direction_priority = popupmenu_is_up and { 's' } or { 'n' }
+  end
+
   local pos = win:get_vertical_direction_and_height(direction_priority, config.max_height)
 
   -- couldn't find anywhere to place the window