ccls does not recognize C attributes

[computerscience-person]

Observed behavior

ccls gives an error on C attributes (feature was standardized in C23 and is supported by clang 9 and gcc 10).

Minimal example:

[[nodiscard]] void* identity(void* item) {
  return item;
}

Expected behavior

No error (feature standardized in C23).

Steps to reproduce

Minimal example:

[[nodiscard]] void* identity(void* item) {
  return item;
}

System information

• ccls version (git describe --tags --long): 0.20240202
• clang version: 14.0.6
• OS: Linux nixos 6.6.32
• Editor: Neovim
• Language client (and version):