misc/wasm: wasm_exec.js missing after toolchain update

[ericcornelissen]

Go version

go version go1.23.0 linux/amd64

Output of go env in your module/workspace:

GO111MODULE=''
GOARCH='amd64'
GOBIN=''
GOCACHE='/home/eric/.cache/go-build'
GOENV='/home/eric/.config/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFLAGS=''
GOHOSTARCH='amd64'
GOHOSTOS='linux'
GOINSECURE=''
GOMODCACHE='/home/eric/go/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='linux'
GOPATH='/home/eric/go'
GOPRIVATE=''
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/home/eric/go/pkg/mod/golang.org/[email protected]'
GOSUMDB='sum.golang.org'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/home/eric/go/pkg/mod/golang.org/[email protected]/pkg/tool/linux_amd64'
GOVCS=''
GOVERSION='go1.23.0'
GODEBUG=''
GOTELEMETRY='on'
GOTELEMETRYDIR='/home/eric/.config/go/telemetry'
GCCGO='gccgo'
GOAMD64='v1'
AR='ar'
CC='gcc'
CXX='g++'
CGO_ENABLED='1'
GOMOD='/home/eric/workspace/ades/go.mod'
GOWORK=''
CGO_CFLAGS='-O2 -g'
CGO_CPPFLAGS=''
CGO_CXXFLAGS='-O2 -g'
CGO_FFLAGS='-O2 -g'
CGO_LDFLAGS='-O2 -g'
PKG_CONFIG='pkg-config'
GOGCCFLAGS='-fPIC -m64 -pthread -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/tmp/go-build283257350=/tmp/go-build -gno-record-gcc-switches'

What did you do?

I updated my Go toolchain version using the Go command's update functionality (I believe this happens automatically when using the go command when the Go version in go.mod doesn't match the current version) and then tried to copy the wasm_exec.js file - following https://go.dev/wiki/WebAssembly - to be able to run WASM compiled Go code in the browser.

What did you see happen?

An error the wasm_exec.js file was not found:

$ cp "$(go env GOROOT)/misc/wasm/wasm_exec.js" .
cp: cannot stat '/home/eric/go/pkg/mod/golang.org/[email protected]/misc/wasm/wasm_exec.js': No such file or directory

if and only if I use a version of the go command from a toolchain update. I verified this error does not occur when Go was installed at go version go1.23.0 linux/amd64 directly.

What did you expect to see?

No error and the file is copied:

$ cp "$(go env GOROOT)/misc/wasm/wasm_exec.js" .

(I know the guide says cp "$(go env GOROOT)/lib/wasm/wasm_exec.js" . - with lib instead of misc - but, at least on Go go version go1.22.5 linux/amd64 and go version go1.23.0 linux/amd64 only misc works.)

[gabyhelp]

Related Issues and Documentation

• cmd/distpack: wasm runtime js should be kept in the toolchain package #68024 (closed)
• cmd/test2json: 'exec format error' for os/exec when exec is set to go_js_wasm_exec #32442 (closed)
• misc/wasm: improve error message when wasm file is not supplied #37000 (closed)
• wasm_exec.js: out-of-sync with runtime.walltime changes #52900 (closed)
• wasm: Running the go wasm example fails using nodejs #61720 (closed)
• syscall/js: nanotime and walltime not compatible with wasm_exec.js #35205 (closed)
• cmd/link: don't resolve WebAssembly imports at link-time #29108
• misc/wasm: using wasm_exec.js in a NodeJs project #35729 (closed)
• misc/wasm: unable to import and use golang created distributed wasm files #65806 (closed)
• wasm: node.js wiki example fails; syntax error in wasm_exec.js reported #27972 (closed)

_{(Emoji vote if this was helpful or unhelpful; more detailed feedback welcome in this discussion.)}

[ericcornelissen]

My bad, this is answered by #68024 - thanks @gabyhelp for helping me find it 🙂

It also explains my confusing with regards to:

I know the guide says cp "$(go env GOROOT)/lib/wasm/wasm_exec.js" . - with lib instead of misc - but, at least on Go go version go1.22.5 linux/amd64 and go version go1.23.0 linux/amd64 only misc works.

because in 1.24.0 it will be in lib instead of misc.

(perhaps the wording here will help other Unix users find the issue too).