CLANGD + ARDUINO + PLATFORMIO

PLATFORMIO.md

1. Select board and generate project
2. Add dependencies to platformio.ini
3. Generate compile_commands.json with pio run -t compiledb
4. Check if there are any errors in a sketch with #include <Arduino.h> related to compiler flags
5. Ignore them in the .clangd configuration file:

CompileFlags:
  # Remove the flags that clangd doesn't understand
  Remove:
    - "-mlongcalls"
    - "-fstrict-volatile-bitfields"
    - "-fno-tree-switch-conversion"

4. Run pio project metadata to display the necessary Arduino includes for clangd

"toolchain": [
"/home/vic/.platformio/packages/toolchain-xtensa-esp32/xtensa-esp32-elf/include/c++/8.4.0",
"/home/vic/.platformio/packages/toolchain-xtensa-esp32/xtensa-esp32-elf/include/c++/8.4.0/xtensa-esp32-elf",
"/home/vic/.platformio/packages/toolchain-xtensa-esp32/lib/gcc/xtensa-esp32-elf/8.4.0/include-fixed",
"/home/vic/.platformio/packages/toolchain-xtensa-esp32/lib/gcc/xtensa-esp32-elf/8.4.0/include",
"/home/vic/.platformio/packages/toolchain-xtensa-esp32/xtensa-esp32-elf/include"
]

5. Add these includes to .clangd

CompileFlags:
  # Add the missing system include paths manually
  Add:
    - "-isystem"
    - "/home/vic/.platformio/packages/toolchain-xtensa-esp32/xtensa-esp32-elf/include/c++/8.4.0"
    - "-isystem"
    - "/home/vic/.platformio/packages/toolchain-xtensa-esp32/xtensa-esp32-elf/include/c++/8.4.0/xtensa-esp32-elf"
    - "-isystem"
    - "/home/vic/.platformio/packages/toolchain-xtensa-esp32/lib/gcc/xtensa-esp32-elf/8.4.0/include-fixed"
    - "-isystem"
    - "/home/vic/.platformio/packages/toolchain-xtensa-esp32/lib/gcc/xtensa-esp32-elf/8.4.0/include"
    - "-isystem"
    - "/home/vic/.platformio/packages/toolchain-xtensa-esp32/xtensa-esp32-elf/include"
    
  # Remove the flags that clangd doesn't understand
  Remove:
    - "-mlongcalls"
    - "-fstrict-volatile-bitfields"
    - "-fno-tree-switch-conversion"

6. Restart clangd and verify

For compatibility with Arduino IDE, main file must be .ino and placed in the root project path with same name as it

Make sure the clangd includes match the board