cmd/go: `go list -json` missing `TestEmbedFiles`

[yz89122]

What version of Go are you using (go version)?

$ go version
go version go1.20.5 darwin/amd64

Does this issue reproduce with the latest release?

Yes

What operating system and processor architecture are you using (go env)?

go env Output

$ go env
GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/Users/aaa/Library/Caches/go-build"
GOENV="/Users/aaa/Library/Application Support/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOINSECURE=""
GOMODCACHE="/Users/aaa/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="darwin"
GOPATH="/Users/aaa/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/Cellar/go/1.20.5/libexec"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/Cellar/go/1.20.5/libexec/pkg/tool/darwin_amd64"
GOVCS=""
GOVERSION="go1.20.5"
GCCGO="gccgo"
GOAMD64="v1"
AR="ar"
CC="cc"
CXX="c++"
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 -arch x86_64 -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/pl/aaa/T/go-build111=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

1. Clone https://github.com/yz89122/go-list-test-embed-error
2. Run go list -json .
3. See the output

What did you expect to see?

Expect field .TestEmbedFiles presented.

What did you see instead?

Field .TestEmbedFiles is missing.

[bcmills]

Hmm. We don't normally need to resolve embed patterns for test sources unless we are actually building the test (which would correspond to the -test flag in go list).

Probably we should do the extra work to resolve them in go list when the fields may be needed (compare #29666).

[yz89122]

Sorry, I didn't realize the field will only presented when the -test flag is given.

Thanks.

[bcmills]

Discussed with @rsc. Our thinking is:

1. Errors in resolving TestEmbedFiles shouldn't cause go list to fail for the non-test package.

2. On the other hand, the -test flag probably shouldn't be needed to populate the fields. (-json, or -f with a template that refers to TestEmbedFiles, should probably suffice.)

But on further consideration, those two points seem to be at odds with each other. 🤔