1 files changed, 6 insertions, 0 deletions
diff --git a/source/blender/draw/engines/overlay/shaders/outline_detect_frag.glsl b/source/blender/draw/engines/overlay/shaders/outline_detect_frag.glsl
index 19d54a57479..ba0a4c0da81 100644
--- a/source/blender/draw/engines/overlay/shaders/outline_detect_frag.glsl
+++ b/source/blender/draw/engines/overlay/shaders/outline_detect_frag.glsl
@@ -358,6 +358,12 @@ void main()
       line_end = vec2(0.0, 0.5);
       break;
     default:
+      /* Ensure values are assigned to, avoids undefined behaviour for
+       * divergent control-flow. This can occur if discard is called
+       * as discard is not treated as a return in Metal 2.2. So
+       * side-effects can still cause problems. */
+      line_start = vec2(0.0);
+      line_end = vec2(0.0);
       break;
   }