Use nullptr instead of NULL
diff --git a/src/hb-ot-shape-complex-use.cc b/src/hb-ot-shape-complex-use.cc
index 4bfbfb8..1f43ac7 100644
--- a/src/hb-ot-shape-complex-use.cc
+++ b/src/hb-ot-shape-complex-use.cc
@@ -144,7 +144,7 @@
   /* "Topographical features" */
   for (unsigned int i = 0; i < ARRAY_LENGTH (arabic_features); i++)
     map->add_feature (arabic_features[i], 1, F_NONE);
-  map->add_gsub_pause (NULL);
+  map->add_gsub_pause (nullptr);
 
   /* "Standard typographic presentation" and "Positional feature application" */
   for (unsigned int i = 0; i < ARRAY_LENGTH (other_features); i++)
@@ -199,7 +199,7 @@
 {
   use_shape_plan_t *use_plan = (use_shape_plan_t *) calloc (1, sizeof (use_shape_plan_t));
   if (unlikely (!use_plan))
-    return NULL;
+    return nullptr;
 
   use_plan->rphf_mask = plan->map.get_1_mask (HB_TAG('r','p','h','f'));
 
@@ -209,7 +209,7 @@
     if (unlikely (!use_plan->arabic_plan))
     {
       free (use_plan);
-      return NULL;
+      return nullptr;
     }
   }
 
@@ -597,17 +597,17 @@
 {
   "use",
   collect_features_use,
-  NULL, /* override_features */
+  nullptr, /* override_features */
   data_create_use,
   data_destroy_use,
-  NULL, /* preprocess_text */
-  NULL, /* postprocess_glyphs */
+  nullptr, /* preprocess_text */
+  nullptr, /* postprocess_glyphs */
   HB_OT_SHAPE_NORMALIZATION_MODE_COMPOSED_DIACRITICS_NO_SHORT_CIRCUIT,
   decompose_use,
   compose_use,
   setup_masks_use,
-  NULL, /* disable_otl */
-  NULL, /* reorder_marks */
+  nullptr, /* disable_otl */
+  nullptr, /* reorder_marks */
   HB_OT_SHAPE_ZERO_WIDTH_MARKS_BY_GDEF_EARLY,
   false, /* fallback_position */
 };