clangd can't find iostream even though there is a valid compile_commands.json

[ghost]

I'm using w64devkit from @skeeto. I have a valid compile_commands.json generated by CMake.

I tried my best. But I'm unable to make clangd to work.

The comment here doesn't help: skeeto/w64devkit#328 (comment)

The AI is powerful. I fed my previous comment into the prompt and it told me to add --driver-mode=c++ to force C++ and --query-driver=C:/w64devkit/bin/g++.exe to force the w64devkit g++. It worked.

clangd doesn't recognize --driver-mode=c++ (this is a clang switch, not clangd switch?).

I inspected with --log=verbose --check=./test.h which test.h only contains #include <iostream>.

clangd sees compile_commands.json, but for unknown reasons it can't find iostream. I'm out of idea.

An LLM said this is normal for clangd, and I have to add -isystem for all the include directories of w64devkit. This is ridiculous!

Note: I set the C++ standard to be C++23. clangd warns about unknown argument -fmodule-ts, but where is that come from? I can't find it in compile_commands.json. It's kind of from nowhere!

I found this thread on @mstorsjo's repo: mstorsjo/llvm-mingw#454

No. --query-driver doesn't help in my case.

[HighCommander4]

Please post clangd logs taken with --log=verbose.