A .clangd file for clangd language server protocol that works with Arduino .ino files. Requires platformio and Arduino app to be installed. Also assumes leonardo board but you can change that in the list of variants

.clangd

// need to add the following to define the Serial class:
// #if defined(DEVELOP)
// extern HardwareSerial Serial;
// #endif
CompileFlags:
  Add: [-xc++, -Wall, -DDEVELOP=1, -I$HOME/.platformio/packages/toolchain-atmelavr/avr/include/, -I$HOME/.platformio/packages/framework-arduino-avr/cores/arduino/, -I/Applications/Arduino.app/Contents/Java/hardware/tools/avr/lib/gcc/avr/7.3.0/include/, -I/Applications/Arduino.app/Contents/Java/hardware/tools/avr/avr/include/avr/, -I/Applications/Arduino.app/Contents/Java/hardware/arduino/avr/libraries/, -I/Applications/Arduino.app/Contents/Java/hardware/arduino/avr/cores/arduino/, -I/Applications/Arduino.app/Contents/Java/hardware/tools/avr/include/libiberty/, -I/Applications/Arduino.app/Contents/Java/hardware/arduino/avr/variants/standard/, -I/Applications/Arduino.app/Contents/Java/hardware/arduino/avr/variants/leonardo/, -I$HOME/.platformio/packages/toolchain-atmelavr/avr/include/avr/, -I$HOME/.platformio/packages/framework-arduino-avr/libraries/SoftwareSerial/src/, -I$HOME/.platformio/packages/framework-arduino-avr/firmwares/atmegaxxu2/arduino-usbserial/, -include HardwareSerial.h, -include Arduino.h]
  Remove: -W*                     # strip all other warning-related flags
  Compiler: clang++               # Change argv[0] of compile flags to `clang++`