I'm making the transition from the official IDE to PlatformIO CLI, and I've run into a problem. While including Arduino.h gives me access to functions such as
digitalWrite(), I can't use the Serial methods. I know that
HardwareSerial.h is the header I need, and I know where to find it on my machine, but I find it suspicious that I can't find it in the PlatformIO's repository.
Anyways, the command
pio lib --storage-dir /opt/arduino-1.8.15/hardware/arduino/avr/cores/arduino/ list
doesn't find anything, yet that's where the headers are. I must be doing something wrong.