Two of M5Stack's own published Cardputer examples fail to build here and
compile fine in the Arduino IDE: SSHClient passes an int to a %lu, and
mic_wav_record has a local GCC thinks may be used uninitialized. ESP-IDF
promotes both categories to errors, which is right for IDF itself and wrong
for a sketch a user pasted from the vendor's repository — the emulator looks
broken for code that is not.
format and maybe-uninitialized join the existing relaxation list, which
already carries comment, parentheses, sign-compare and the rest for exactly
this reason. They stay warnings, so the diagnostic is still printed; -Wall is
untouched.