As a stopgap you may be interested in this:
https://github.com/marcmerlin/Neopixel-IR/blob/v1.0/Neopixel-IR.ino#L275
My code handles 4 different neopixel libraries and their different APIs, and allows you to run the adafruit demo code.
Feel free to take my code and add it in your examples if you wish.
However in the meantime, thank you for writing this lib, brilliant idea (yes I know it came from other code). I've used it to do neopixels plus IR which otherwise wasn't possible: http://marc.merlins.org/perso/arduino/post_2017-04-03_Arduino-328P-Uno-Teensy3_1-ESP8266-ESP32-IR-and-Neopixels.html this short video shows how trying this on AVR is an exercise in frustration and handling failures :) https://www.youtube.com/watch?v=62-nEJtm070
As a stopgap you may be interested in this: https://github.com/marcmerlin/Neopixel-IR/blob/v1.0/Neopixel-IR.ino#L275 My code handles 4 different neopixel libraries and their different APIs, and allows you to run the adafruit demo code. Feel free to take my code and add it in your examples if you wish.