How to compile only chdman under web assembly?

[Kelvao]

I tried:
emmake make WEBASSEMBLY=1 TOOLS=1 NOWERROR=1 -j$(nproc)

I have 2 issues to build:

Emscripten's libc already defines struct _IO_FILE (the internal glibc FILE layout). MAME's SDL OSD layer redeclares the same struct with a full body, which collides with Emscripten's own definition and fails to compile.
chdman only needs a small slice of MAME's codebase, but GENie generates link flags as if the full emulator were being linked. That leaves symbols referenced by unused code paths undefined, and Emscripten's linker treats undefined symbols and warnings as hard errors (-Werror, ERROR_ON_UNDEFINED_SYMBOLS=1) by default.
I think I resolved the issue in my project. I use a pipeline to handle the build with the latest mame and emsdk version. Here is the project, in case it’s useful:
https://github.com/Kelvao/RetroShrink
It is still in the early stages, so the web page isn't using chdman yet.

[holub]

A little bit more details about error details (and emscripten/clang versions) can help the person who trying to help you not to try your command locally and respond "works here".

[Kelvao]

I have 2 issues to build:

• Emscripten's libc already defines struct _IO_FILE (the internal glibc FILE layout). MAME's SDL OSD layer redeclares the same struct with a full body, which collides with Emscripten's own definition and fails to compile.
• chdman only needs a small slice of MAME's codebase, but GENie generates link flags as if the full emulator were being linked. That leaves symbols referenced by unused code paths undefined, and Emscripten's linker treats undefined symbols and warnings as hard errors (-Werror, ERROR_ON_UNDEFINED_SYMBOLS=1) by default.

I think I resolved the issue in my project. I use a pipeline to handle the build with the latest mame and emsdk version. Here is the project, in case it’s useful:
https://github.com/Kelvao/RetroShrink
It is still in the early stages, so the web page isn't using chdman yet.

[holub]

I would recommend you to try 3.1.35 first