Go 1.17: LinkError: import object field 'runtime.walltime' is not a Function

[nekrondev]

I updated my Go compiler and it looks like wasm_exec.js got updated within the runtime so launching the WASM failed with
LinkError: import object field 'runtime.walltime' is not a Function

It looks like walltime1() is used in the static generated script.go whereas Go 1.17 changed from walltime1() to walltime() hence the missing function exception.

[maxence-charriere]

I will take a look on it. Thanks for reporting it.

[beanpole135]

I just ran into this as well, and from looking up the information about WASM from the Go devs, it sounds like there is a history about that wasm_exec.js file changing between versions of Go, so a static-version of that file in the go-app repo is probably not a good idea for future version updates either.

It looks like the wasm_exec.js that is used needs to come from the current version of the go compiler installed on the system doing the build - since the Go devs ensure that the wasm_exec.js distributed with Go is always compatible, but that file has no backward/forward compatibility guarantee.

That file is located at "/usr/share/go/misc/wasm/wasm_exec.js" on my Linux system here, but I think you can dynamically fetch the go installation path within go itself and just copy that file at build-time instead.

[beanpole135]

More info:
It looks like go-app already does that "wasm_exec.js" find/embed routine here: https://github.com/maxence-charriere/go-app/blob/master/pkg/app/gen/scripts.go

So a short-term solution would be to just release a new package for go-app (v9-XYZ) which was build on a system using Go 1.17

Longer term: a way to move that generation routine out of the go-app pre-packaging framework (go generate) and into some kind of "setup routine" that a developer can run/re-run on their system as needed instead. Alternatively, I think I have seen other go-based WASM systems actually drop the wasm_exec.js file into the root dir of the files for the site itself, and then the server dynamically reads/uses that file (with caching as needed) instead of having a static string in memory.

[maxence-charriere]

Hey, yes so it looks like they have changed some stuff in the js support file.
Since wasm is still experimental, some stuff like that can likely happen.

I'll release v9 with the 1.17 requirement. in the meantime you can get a v9 build where it is fixed with this:

go get -u -v github.com/maxence-charriere/go-app/v9@a26b536

Working on releasing v9 soon.

[beanpole135]

That new v9 tag works great on my go 1.17 system. Thanks!