wajic VS memfs

This is a slim alternative to Emscripten which focuses only on the C/C++ <=> JS interoperability part:

https://github.com/schellingb/wajic

There's actually a super interesting project called wajic here:

https://github.com/schellingb/wajic

It's basically clang plus wasm-opt and some magic pixie dust which enables some of the most important features of Emscripten, but without the whole 'technology zoo' :)

There's now an interesting alternative to Emscripten called WaJIC:

https://github.com/schellingb/wajic

Enables most of the "Emscripten magic" (like embedding Javascript code into C/C++ files), but in a more bare bones package (apart from clang it essentially just uses the wasm-opt tool from Binaryen for post-processing).

(to be clear, wajic has fewer out-of-the-box features than Emscripten, but it might be an alternative for very small projects which don't need all the compatibility shims which are coming with Emscripten, while still providing tools for calling between C/C++ and JS.

Since I haven't seen it mentioned in the comments yet, here's another interesting project in the general area of "WASM without Emscripten":

https://github.com/schellingb/wajic

This provides an alternative implementation of Emscripten's EM_JS() magic (embed Javascript snippets right in the C/C++ source code), but without the Emscripten SDK. It still needs some additional tools next to Clang, so it sits somewhere between "pure Clang" and "full Emscripten SDK".

Alas, although there is WebAssembly support in the original dos-like, it is still not supported in the bindings for Rust. It would require a Rust toolchain to integrate with WAjic, which I am pretty much unfamiliar with. If you have any idea on how to achieve this, I would love to know.

I am using the Python ecosystem (with full support for dynamic loading of C extension modules) as an initial motivating project. Also, the Python test suite is extremely useful to root out problems. I certainly hope that this can provide a more complete alternative to Emscripten to the community eventually. That said, Emscripten is huge, and the problems involved in creating a more maintainable modular WASM build tool are subtle. For example, when implementing a custom module loader for Python-wasm last week, I discovered several bugs in the memfs and unionfs Javascript libraries (https://github.com/streamich/memfs/pulls?q=is%3Apr+author%3A... and https://github.com/streamich/unionfs/pulls?q=is%3Apr+author%...). I had to learn the code sufficiently to fix all these bugs, submit PR's, etc. Emscripten has its own analogue of memfs, which is optimized specifically for WebAssembly in the browser, where memfs is a more general widely used library (with 10M+ downloads/week).

CoWasm has no support for asyncify. Where I've run into setjmp/longjmp so far, I've been rewriting the code instead. E.g., the dash shell uses setjmp/longjmp, and I'm rewriting that to use return error codes instead (see, e.g., https://github.com/sagemathinc/dash/commit/7117e1f6496728af0...).

> how would I go about porting a simple C->WASM w/ Typescript library project to CoWasm?

That's a great question, which I'm not sure how to quickly answer, so I've created a discussion item here https://github.com/sagemathinc/cowasm/discussions/40

Looks like this whole thing was motivated by the fact that, in order to get the encrypted PDF in a Buffer like they wanted, they had to save to disk and load it back. They could have instead used an in-memory filesystem such as https://github.com/streamich/memfs and just made the existing PDF library that was almost right use that.

How do I populate the input files? The filesystem API in emscripten talks about MEMFS, is that the same as this? https://github.com/streamich/memfs