Use runno-clang to compile cpp code locally

[swwind]

Hello @taybenlor, I'm trying to implement a little runno-like plugin for my project nowadays, but I'm having a headache trying to solve some complicated issues with clang and runno-clang.

I have my machine with wasmer 2.3.0 and wapm 0.5.5 installed, and I'm trying to compile my cpp code with runno-clang. I copied compile command from provider.ts and try to run it on my machine, but it fails.

// example.cpp
#include <stdio.h>
int main() {
  printf("hello world");
}

wapm run runno-clang --dir=. \
  -cc1 \
  -Werror \
  -emit-obj \
  -disable-free \
  -isysroot /sys \
  -internal-isystem /sys/include/c++/v1 \
  -internal-isystem /sys/include \
  -internal-isystem /sys/lib/clang/8.0.1/include \
  -ferror-limit 4 \
  -fmessage-length 80 \
  -fcolor-diagnostics \
  -O2 \
  -o program.o \
  -x c++ \
  -v \
  ./example.cpp

clang -cc1 version 8.0.1 based upon LLVM 8.0.1 default target wasm32-wasi
ignoring nonexistent directory "/sys/usr/local/include"
ignoring nonexistent directory "../lib/clang/8.0.1/include"
ignoring nonexistent directory "/sys/usr/include"
ignoring duplicate directory "/sys/include/c++/v1"
ignoring duplicate directory "/sys/include/c++/v1"
#include "..." search starts here:
#include <...> search starts here:
 /sys/include/c++/v1
End of search list.
In file included from ./example.cpp:1:
/sys/include/c++/v1/stdio.h:108:15: fatal error: 'stdio.h' file not found
#include_next <stdio.h>
              ^~~~~~~~~
1 error generated.

The weird is that two ignoring duplicate directory "/sys/include/c++/v1" errors in clang, I have three different include paths but it seems only receives the first include path and ignores others. I'm not sure who causes the problem but the same command and code seems to work in runno.run.

P.S. clang also have the same behavior (ignores other include paths).

Do you have any idea on this?

[swwind]

And runno.run works very well 😢

[taybenlor]

Hi! Thanks for reaching out!

Not sure how helpful I can be. I think the important output here is:

ignoring nonexistent directory "/sys/usr/local/include"
ignoring nonexistent directory "../lib/clang/8.0.1/include"
ignoring nonexistent directory "/sys/usr/include"
ignoring duplicate directory "/sys/include/c++/v1"
ignoring duplicate directory "/sys/include/c++/v1"

If you have a look at https://github.com/taybenlor/clang you'll see that it includes a sysroot folder. If you look at the wapm.toml file it sets up the sysroot to be mounted to /sys. I'm guessing this step isn't being done automatically by WAPM for some reason?

BTW my https://github.com/taybenlor/clang (runno-clang on WAPM) is just a fork of clang on WAPM. I just replaced the wasm binaries with the original ones from binji's talk which seemed to work better for C++.

[swwind]

As a matter of fact, wapm does the mount job automatically, it more looks like the problem to clang or the wasmer runner itself. The thing is, clang does not respect my -internal-isysroot argument and thus cannot find where the include file located.

I found a similar crash report here, the same compile command does not seem to work on native environments.

I may report this to wasmer if this does not seem to be the clang.wasm binary problem.

[swwind]

If you give 1 -internal-isystem /sys/include/c++/v1 and 1000 -internal-isystem /sys/include, you will get 1000 ignoring duplicate directory "/sys/include/c++/v1". There was something definitely wrong.

[taybenlor]

How'd you go with this? Need any further help?

[swwind]

I found it was a wasmer bug, and wasmtime works. So I decided to use wasmtime instead.

[taybenlor]

Great, thanks!