examples/wasm: update export example to show the use of the go:wasmimport directive

[deadprogram]

This PR updates the wasm "export" example to show the use of the go:wasmimport directive. See #3165 for details.

[aykevl]

//go:wasmimport is meant for only importing functions, but it also unintentionally exports functions.

Do we want to officially support that, or add a new //go:wasmexport instead?

[deadprogram]

The proposal at golang/go#38248 was accepted and already implemented here golang/go@02411bc so in the interest of keeping compatibility we should probably do the same thing for now.

[achille-roussel]

I think this update is premature, go:wasmimport is only supported on functions with no body that get linked at runtime to exports of other modules.

Here it seems that the //export directive is intended to ask the compiler to add the function to the list of exports of the module, or am I missing something?

[deadprogram]

Ah OK. I totally misunderstood what was happening here. Thanks for the clarification.

[aykevl]

I have made a PR to fix this: #3610
It should make this PR (intentionally) fail.

That said, I do agree it would be a good idea to add an example with //go:wasmimport, but make it an actual import instead of an export.

[deadprogram]

It should make this PR (intentionally) fail.

I think the best thing to come out of this PR is to prevent me from doing what is in this PR. 😸

Thanks @achille-roussel and @aykevl

I will close this one since it does not actually do anything we need.