commit https://github.com/vim/vim/commit/1b58cdd160c2e0ada0f638679a2aa27e4665fc48 Author: Bram Moolenaar <Bram@vim.org> Date: Mon Aug 22 23:04:33 2016 +0200 patch 7.4.2243 Problem: Warning for assigning negative value to unsigned. (Danek Duvall) Solution: Make cterm_normal_fg_gui_color and _bg_ guicolor_T, cast to long_u only when an unsigned is needed.

--- a/src/gui.c
+++ b/src/gui.c
@@ -4741,7 +4741,7 @@ gui_get_color(char_u *name)
     int
 gui_get_lightness(guicolor_T pixel)
 {
-    long_u	rgb = gui_mch_get_rgb(pixel);
+    long_u	rgb = (long_u)gui_mch_get_rgb(pixel);
 
     return  (int)(  (((rgb >> 16) & 0xff) * 299)
 		   + (((rgb >> 8) & 0xff) * 587)