cmd/go: go env does not show GODEBUG

[mvdan]

Go version

go version devel go1.23-86a32d6d9c 2024-02-17 06:03:15 +0000 linux/amd64

Output of go env in your module/workspace:

GO111MODULE=''
GOARCH='amd64'
GOBIN=''
GOCACHE='/home/mvdan/.cache/go-build'
GOENV='/home/mvdan/.config/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFLAGS=''
GOHOSTARCH='amd64'
GOHOSTOS='linux'
GOINSECURE=''
GOMODCACHE='/home/mvdan/go/pkg/mod'
GONOPROXY='github.com/cue-unity'
GONOSUMDB='github.com/cue-unity'
GOOS='linux'
GOPATH='/home/mvdan/go'
GOPRIVATE='github.com/cue-unity'
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/home/mvdan/tip'
GOSUMDB='sum.golang.org'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/home/mvdan/tip/pkg/tool/linux_amd64'
GOVCS=''
GOVERSION='devel go1.23-86a32d6d9c 2024-02-17 06:03:15 +0000'
GCCGO='gccgo'
GOAMD64='v3'
AR='ar'
CC='gcc'
CXX='g++'
CGO_ENABLED='1'
GOMOD='/dev/null'
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-build1777333942=/tmp/go-build -gno-record-gcc-switches'

What did you do?

Set GODEBUG and expect go env or go env GODEBUG to show me. Particularly now that its value can change the behavior of the standard library, e.g. GODEBUG=gotypesalias=1.

What did you see happen?

$ export GODEBUG=gotypesalias=1
$ go env | grep GODEBUG
$ go env GODEBUG

$ 

What did you expect to see?

$ export GODEBUG=gotypesalias=1
$ go env | grep GODEBUG
GODEBUG=gotypesalias=1
$ go env GODEBUG
gotypesalias=1
$ 

[mvdan]

cc @bcmills @matloob

[gopherbot]

Change https://go.dev/cl/565095 mentions this issue: cmd/go/internal/envcmd, internal/cfg: show GODEBUG for command 'go env'

[bcmills]

I think this was an oversight from #56986, which made GODEBUG much more prominent (and gave it quite a bit more official support).

[bcmills]

See also:

• cmd/go: go test cache unaffected by GODEBUG value #65436
• cmd/go: separate default GODEBUGs from go language version #65573

[gopherbot]

Change https://go.dev/cl/566097 mentions this issue: cmd/go/internal/envcmd: show GODEBUG in 'go env' output

[rsc]

It seems like go env should support printing GODEBUG, since it is relevant to debugging problems with go generally. But since GODEBUG is a runtime setting, not a build-time setting, go env -w GODEBUG=foo should not work, since it would be writing the setting into a file the runtime does not read. (Nor should every Go program read that file on startup.)

[mvdan]

That makes sense to me. Thanks for the fix!