added an assertion

diff --git a/src/mesa/state_tracker/st_cb_clear.c b/src/mesa/state_tracker/st_cb_clear.c
index 2583b4f1bd534790c4f60abb1322118adce258f3..80f136e0a673c112da1f996ce261ba8897407d77 100644 (file)
--- a/src/mesa/state_tracker/st_cb_clear.c
+++ b/src/mesa/state_tracker/st_cb_clear.c
@@ -454,8 +454,10 @@ static void st_clear(GLcontext *ctx, GLbitfield mask)
       GLuint b;
       for (b = 0; b < BUFFER_COUNT; b++) {
          if (BUFFER_BITS_COLOR & mask & (1 << b)) {
-            clear_color_buffer(ctx,
-                               ctx->DrawBuffer->Attachment[b].Renderbuffer);
+            struct gl_renderbuffer *rb
+               = ctx->DrawBuffer->Attachment[b].Renderbuffer;
+            assert(rb);
+            clear_color_buffer(ctx, rb);
          }
       }
    }