Use nullptr instead of 0.

src/hb-coretext.cc

@@ -314,7 +314,7 @@ _hb_coretext_shaper_font_data_destroy (hb_coretext_shaper_font_data_t *data)
 hb_font_t *
 hb_coretext_font_create (CTFontRef ct_font)
 {
-  CGFontRef cg_font = CTFontCopyGraphicsFont (ct_font, 0);
+  CGFontRef cg_font = CTFontCopyGraphicsFont (ct_font, nullptr);
   hb_face_t *face = hb_coretext_face_create (cg_font);
   CFRelease (cg_font);
   hb_font_t *font = hb_font_create (face);
@@ -1045,7 +1045,7 @@ resize_and_retry:
 	  }
 	if (!matched)
 	{
-	  CGFontRef run_cg_font = CTFontCopyGraphicsFont (run_ct_font, 0);
+	  CGFontRef run_cg_font = CTFontCopyGraphicsFont (run_ct_font, nullptr);
 	  if (run_cg_font)
 	  {
 	    matched = CFEqual (run_cg_font, cg_font);

src/test-buffer-serialize.cc

@@ -101,7 +101,7 @@ main (int argc, char **argv)
 
   bool ret = true;
   char line[BUFSIZ], out[BUFSIZ];
-  while (fgets (line, sizeof(line), stdin) != 0)
+  while (fgets (line, sizeof(line), stdin) != nullptr)
   {
     hb_buffer_clear_contents (buf);