Remove --wasm2asm flag, use binaryen directly

[bspeice]

Binaryen renamed the tool to wasm2js instead of wasm2asm - WebAssembly/binaryen#1642

[bspeice]

The failing job is test-web-sys, and seems unrelated to what I'm proposing here. Should I be concerned about that?

[alexcrichton]

Thanks for the PR! I think though that --wasm2asm is basically a deprecated mode now that wasm2js exists, as the output of wasm2js shoudl be equivalent to wasm2es6js --wasm2asm. If you use the wasm2js tool though is it not working for you?

[bspeice]

It's working fine, I just wanted to update things since this blog post recommended use of wasm2asm mode, and recent releases of binaryen broke that. Don't have a huge preference on rename vs. remove, but I was confused for a while as to why the command was breaking.

[alexcrichton]

Ah ok, great! If we want to keep the --wasm2asm mode working here then I think we'll want to tweak this PR to just simply forward to wasm2js and don't worry about the rest of the output

[bspeice]

Not totally sure what you mean - are you referring to keeping the --wasm2asm flag live in wasm-bindgen and just changing the internal call to binaryen to use wasm2js?

[alexcrichton]

Well I'm not entirely sure. It sounds like you want to keep the --wasm2asm flag, right? (to keep the blog post working?)

If so, then this implemention is incorrect because it will wrap ES imports twice, once by wasm2js and once by this tool.

Deleting --wasm2asm is fine by me, but otherwise keeping it working is also fine by me but will require a different patch.

[bspeice]

Ah, that makes more sense. I'm actually mostly in favor of deleting the flag; if it's just a shim around binaryen I'd rather reduce functionality and make a note in the docs that functionality provided by wasm2asm is now a part of wasm2js in binaryen. I'll get started on that unless I hear otherwise.

[alexcrichton]

Sounds good to me!

[alexcrichton]

Thanks!