cmd/go: misleading error message with repeated folder name

[Deleplace]

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

$ go version
go version go1.17.1 linux/amd64

Does this issue reproduce with the latest release?

Yes with 1.17.6

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

go env Output

$ go env
GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/root/.cache/go-build"
GOENV="/root/.config/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GOMODCACHE="/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"
GOVCS=""
GOVERSION="go1.17.6"
GCCGO="gccgo"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD="/server/go.mod"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build1185892953=/tmp/go-build -gno-record-gcc-switches"

What did you do?

We have

• a private repo at github.com/MyAccount/my-repo
  • containing a file server/go.mod starting with the line module github.com/MyAccount/my-repo/server
  • having the semver git tag server/v0.0.2
• a distinct "client" project, having its own go.mod containing the lines

require (
	github.com/MyAccount/my-repo/server v0.0.2
)

Inside the "client" project, we launched

go build

(Sorry, can't give the full reproducible details of our private repo!)

What did you expect to see?

...
go: downloading github.com/MyAccount/my-repo/server v0.0.2
cmd/client/main.go:4:2: reading github.com/MyAccount/my-repo/server/go.mod at revision server/v0.0.2: git ls-remote -q origin in /go/pkg/mod/cache/vcs/f685fe342419a0c5eddd96688c386faf8f7622fa76c707a9c1c7c68bc353b5fe: exit status 128:
      Host key verification failed.
      fatal: Could not read from remote repository.

What did you see instead?

...
go: downloading github.com/MyAccount/my-repo/server v0.0.2
cmd/client/main.go:4:2: reading github.com/MyAccount/my-repo/server/server/go.mod at revision server/v0.0.2: git ls-remote -q origin in /go/pkg/mod/cache/vcs/f685fe342419a0c5eddd96688c386faf8f7622fa76c707a9c1c7c68bc353b5fe: exit status 128:
      Host key verification failed.
      fatal: Could not read from remote repository.

Note that the only unexpected bit is the repeated word at server/server.

This seems misleading: when seeing this error message, we thought that the "wrong" path github.com/MyAccount/my-repo/server/server/go.mod was the cause of the build failure. Did we make a mistake somewhere in the repo name/module name/package name/folder name?

We then realized that the root cause was only due to authentication difficulties with the go command using HTTPS or SSH to download the private repo.

After discussing this surprising error message with some Gophers, we now think the error message should not repeat the word "server" in the printed path.

[Deleplace]

@rsc I'll see if I can pinpoint a relevant line in the code source.

If it helps, I may create sample repos to reproduce the error message (probably in a Docker container).

[Deleplace]

The relevant method in go internals is (*codeRepo).findDir .

[gopherbot]

Change https://go.dev/cl/386234 mentions this issue: cmd/go/internal/modfetch: avoid duplicating path components in Git fetch errors