Rename fn to main_js in guide/src/reference/attributes/on-rust-exports/start.md

[Urhengulas]

Because the tests fail, when a function annotated with #[wasm_bindgen(start)] is named main, this PR changes the name in the example in the wasm_bindgen book to main_js and says, that it can't be named main.

The information that it can't be named main is from rust-gamedev/wg#51, and solved #2206.

Changes

• rename function from main to main_js
• add hint that function can't be named main

[alexcrichton]

Thanks for the PR! I don't think this is quite right though. You can indeed have a function called main. Is it perhaps specific to the context of the gamedev area that they've already got a symbol called main somewhere else? It may be the case that a different crate you're using already defines main, which means you can't define main yourself when using that crate.

[Urhengulas]

If you say so that is probably true and in my experience it is also for the wasm-pack build.

But it doesn‘t work for wasm-pack test --node (or browser) and the only dev-dependency I am having is wasm-bindgen-test = "0.3.13".

My main dependency https://github.com/xiph/rav1e is defining a lib and a bin crate, but I am only „using“ the lib.

[17cupsofcoffee]

The information that it can't be named main is from rust-gamedev/wg#51

To add some context: I raised that issue before #1630 was created/merged, so the info in the first post of rust-gamedev/wg#51 is now outdated. I was referring to the fact that you previously had to wrap your existing main in a #[wasm_bindgen(start)] annotated function in order to get a binary crate running on WASM, but that's no longer the case.

I've updated my issue to reflect this, sorry for the confusion!

[Urhengulas]

Thank you @17cupsofcoffee for clarifying.

So it seems I had some weird edge-case problem, which accidentally could be resolved with this outdated information. Nice 😎

I am a bit worried other people might also encounter this, but I am going to close the issue.

Thanks everyone :)