Re: [meson.bbclass] bindgen_clang_arguments lacks C++ include paths, breaks C++ bindgen (mesa rusticl)

[Royyan Zahir <royzah@gmail.com>]

Hi Paul,

Thanks for looking. Versions first, then the trigger, then what I have not yet
established.

Layers, all pinned:

  openembedded-core  wrynose  f7397af248e1e338929d70a910b0fbc2341528ec
  bitbake            2.18     0ad6c1c34a5e07a5f8dd66ab248c1e7b37b69fa9
  meta-openembedded  wrynose  14282a02be9c74a1276a7cda7d6c89e054699a11
  meta-qcom          wrynose  ef0004df267743cc89d6a09bc724bc99ff541c01

Target is aarch64, mesa 26.0.5, LLVM 22.1.3, bindgen from bindgen-cli-native.

The trigger is only this:

  DISTRO_FEATURES:append = " opencl"

which selects mesa's PACKAGECONFIG[opencl], so -Dgallium-rusticl=true, and the
rusticl frontend runs bindgen over a C++ header. The failing command ends with
-x c++ -std=c++17 on rusticl_llvm_bindings.hpp, and clang cannot find cassert
from llvm/ADT/DenseMapInfo.h.

What I cannot give you is a runnable command line: our DISTRO and MACHINE are
in a layer I cannot share, and I have not yet reduced this to stock poky. I
tried to on the shared builder this morning and it refused before parsing with

  ERROR: User namespaces are not usable by BitBake, possibly due to AppArmor.

so that attempt proved nothing. Our own builds go through a wrapper that
handles it.

My reading is that nothing platform-specific is involved: bindgen_args() in
meson.bbclass passes HOST_CC_ARCH, TOOLCHAIN_OPTIONS and --target, and none of
those carry the libstdc++ include directories that clang needs when it
cross-compiles against a GCC sysroot. Any meson recipe running bindgen over a
C++ header should hit it. If that reasoning is wrong I would rather know than
have you chase our stack.

Happy to build a stock qemuarm64 case with opencl in DISTRO_FEATURES on a
machine without the namespace restriction and report back, or to test a patch
on aarch64, whichever is more useful.

Royyan