[buffer] HB_NODISCARD next_glyphs()

src/hb-buffer.cc

@@ -319,7 +319,7 @@ hb_buffer_t::swap_buffers ()
   if (unlikely (!successful)) return;
 
   assert (idx <= len);
-  next_glyphs (len - idx);
+  if (unlikely (!next_glyphs (len - idx))) return;
 
   assert (have_output);
   have_output = false;

src/hb-buffer.hh

@@ -280,7 +280,7 @@ struct hb_buffer_t
   }
   /* Copies n glyphs at idx to output and advance idx.
    * If there's no output, just advance idx. */
-  bool next_glyphs (unsigned int n)
+  HB_NODISCARD bool next_glyphs (unsigned int n)
   {
     if (have_output)
     {

src/hb-ot-shape-normalize.cc

@@ -348,7 +348,7 @@ _hb_ot_shape_normalize (const hb_ot_shape_plan_t *plan,
 						      sizeof (buffer->info[0]),
 						      &buffer->cur().glyph_index(),
 						      sizeof (buffer->info[0]));
-	buffer->next_glyphs (done);
+	if (unlikely (!buffer->next_glyphs (done))) break;
       }
       while (buffer->idx < end && buffer->successful)
 	decompose_current_character (&c, might_short_circuit);