support //go:wasmimport or a similarly named alias for imported functions

[codefromthecrypt]

Let's support //go:wasmimport or a similarly named alias for imported functions. This would be an alias to //export, so that existing code can work, but much more intuitive. By being more intuitive, new users have a better experience, and we have less load on issues as well less angst on support.

Background

Currently, users need to add the keyword //export in order to import a function (ex from the wasm host).

ex.

//go:wasm-module env
//export log
func _log(ptr uint32, size uint32)

This is very unintuitive and provides a bad first time experience for TinyGo users. It also occupies many issues and in doing so steals time from folks contributing support. A couple examples are #3000 and #455, but there are many more occurrences than this, including my personal first experience.

As far as I understand the history from @aykevl,

"Export" in this case really means "make available to C" - either as a declaration or a definition.

I would argue that this can be true, but jargon that doesn't match is also more confusing than re-use of some C related jargon in Go. Many Go developers won't think through like this, hence the continual support questions.

More background could be that Go didn't have an import keyword. For example, In Go, you need to define a .s file then use a CallImport instruction there. The point remains that it also uses the word import not export for this.
https://github.com/golang/go/blob/master/src/syscall/js/js_js.s#L63-L65

However, if you look at the latest on Go, golang/go#38248, it appears //go:wasmimport would be used, not //export, for importing functions.

[fgsch]

fwiw, TinyGo also supports //go:export, which is what //export is rewritten to.

[james-lawrence]

minor note that a guide should include a end to end example of a module exporting a function, another module importing it, and then executing the resulting modules. something along this line.

[codefromthecrypt]

@james-lawrence forked an issue for your above comment so it doesn't end up lost. This example can be made now and syntax changed later (among the other ones) #3154

[aykevl]

I missed the fact that //go:wasmimport is now accepted upstream. This means we're free to use it.
I made a PR to add support for it: #3165

Long term, I'd also like to change the behavior of //export so it isn't a wasm export, and instead use a //go:wasmexport or something similar. But there is a much greater risk at incompatibility with that with the upstream Go toolchain, so I'm not entirely sure about it. (Of course, there will be a transition period for such a rather big change).

[deadprogram]

#3165 was merged into dev branch, so marking this issue for next release.

[deadprogram]

This was completed as part of release v0.28 so now closing. Thanks!