[gnome-builder] omni-gutter: fix signedness issues

[Christian Hergert <chergert src gnome org>]

commit 6838f494db0bec98f1b1afee32e955448447d5d3
Author: Christian Hergert <chergert redhat com>
Date:   Sun Jan 14 23:47:20 2018 -0800

    omni-gutter: fix signedness issues
    
    We need to make sure we don't promote integer into unsigned math, or we
    will get vastly out of area coordinates.
    
    Improves #255

 src/libide/sourceview/ide-omni-gutter-renderer.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)
---
diff --git a/src/libide/sourceview/ide-omni-gutter-renderer.c 
b/src/libide/sourceview/ide-omni-gutter-renderer.c
index f913f0f67..aade92830 100644
--- a/src/libide/sourceview/ide-omni-gutter-renderer.c
+++ b/src/libide/sourceview/ide-omni-gutter-renderer.c
@@ -510,15 +510,13 @@ calculate_diagnostics_size (gint height)
 {
   static guint sizes[] = { 64, 48, 32, 24, 16, 8 };
 
-  height -= 2; /* Subtract padding */
-
   for (guint i = 0; i < G_N_ELEMENTS (sizes); i++)
     {
       if (height >= sizes[i])
         return sizes[i];
     }
 
-  return 16;
+  return sizes [G_N_ELEMENTS (sizes) - 1];
 }
 
 static void
@@ -978,7 +976,7 @@ draw_diagnostic (IdeOmniGutterRenderer        *self,
                  cairo_t                      *cr,
                  GdkRectangle                 *area,
                  LineInfo                     *info,
-                 guint                         diag_size,
+                 gint                          diag_size,
                  GtkSourceGutterRendererState  state)
 {
   cairo_surface_t *surface = NULL;