callMain not exported

[r0ller]

Hi All,

When trying to run clang in the browser by Module.callMain() after having compiled llvm-15 (the same what my emscripten version is based on) with emscripten itself, I get a runtime error saying "Uncaught ReferenceError: callMain is not defined". However, as you can see in the build command, I do list it in EXPORTED_RUNTIME_METHODS.
How shall it be exported?

Thanks for any hints in advance!

BR,
r0ller

Version of emscripten/emsdk:
3.1.6 - stock package from Ubuntu 24.04 LTS

Command line in full:

llvm-project$ export CXXFLAGS="-Dwait4=__syscall_wait4"
llvm-project$ export LDFLAGS="-s ALLOW_MEMORY_GROWTH=1 -s EXPORTED_RUNTIME_METHODS=\"['callMain','FS']\" -s ERROR_ON_UNDEFINED_SYMBOLS=0"
llvm-project$ emcmake cmake -G Ninja -S ./llvm/ -B ./build -DLLVM_ENABLE_LIBCXX=OFF -DCMAKE_BUILD_TYPE=Release -DLLVM_TARGETS_TO_BUILD=WebAssembly -DLLVM_ENABLE_PROJECTS="clang;lld" -DLLVM_ENABLE_DUMP=OFF -DLLVM_ENABLE_ASSERTIONS=OFF -DLLVM_ENABLE_EXPENSIVE_CHECKS=OFF -DLLVM_ENABLE_BACKTRACES=OFF -DLLVM_BUILD_TOOLS=OFF -DCLANG_BUILD_TOOLS=OFF -DLLVM_ENABLE_THREADS=OFF -DLLVM_BUILD_LLVM_DYLIB=OFF -DLLVM_INCLUDE_TESTS=OFF -DLLVM_BUILD_TESTS=OFF -DLLVM_INCLUDE_EXAMPLES=OFF -DLLVM_INCLUDE_BENCHMARKS=OFF -DLLVM_TABLEGEN=/usr/bin/llvm-tblgen-15 -DCLANG_TABLEGEN=native/bin/clang-tblgen
llvm-project$ cd build
llvm-project$ ninja clang lld

[sbc100]

Can you run ninja with -v and show the full link command that is used for clang?

Is there some reason you are using the very old 3.1.6 release? The release is 4.5 years old at this point.

I can see the for simple programs it certainly is possible to export callMain:

$ emcc -sEXPORTED_RUNTIME_METHODS=callMain test/hello_world.c
$ grep callMain a.out.js
  Module['callMain'] = callMain;
function callMain() {
  if (!noInitialRun) callMain();

Here you can see the function being defined and exported on the Module object.

[brendandahl]

Maybe that old version needs to use EXTRA_EXPORTED_RUNTIME_METHODS instead?

[r0ller]

Thanks for the suggestions but none of them worked. Using EXTRA_EXPORTED_RUNTIME_METHODS hasn't changed anything. Compiling a simple test code to test if callMain gets exported:

int main(int argc, char *argv[]){
  return argc;
}

also results only in the following when grepping for callMain:
Module["callMain"] = callMain;

What's next? Shall I just try the newest version? Actually, there's no specific reason for using 3.1.6 just that it was available via apt.

[r0ller]

Installed latest emsdk and after compiling the simple test code above, grep finds callMain being exported. So I'll just go on with the latest version. Thanks for your help!