cmd/go: 'looping trying to add package' when running 'mod tidy' with a package not found in the containing module

[sagikazarmark]

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

$ go version
go version go1.11.5 darwin/amd64

Does this issue reproduce with the latest release?

Yes, it does (at the time of writing 1.11.5 is the latest).

Note: reproduced the issue with go1.12rc1 as well

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

go env Output

$ go env
GOARCH="amd64"
GOBIN=""
GOCACHE="/Users/mark/Library/Caches/go-build"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOOS="darwin"
GOPATH="/Users/mark/.go:/Users/mark/Projects/go"
GOPROXY=""
GORACE=""
GOROOT="/usr/local/go"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/darwin_amd64"
GCCGO="gccgo"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD="/Users/mark/Projects/go/src/github.com/banzaicloud/pipeline/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 -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/vy/hzm88gt90292ztr9f3qg9zhr0000gn/T/go-build985692952=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

git clone [email protected]:banzaicloud/pipeline.git
export GO111MODULE=on
git checkout ce96c5fd39bbb2558a4dff50258cc9634a9749ac
go mod init
go mod edit -replace=github.com/qor/auth@master=github.com/banzaicloud/auth@master`
go mod tidy

What did you expect to see?

Go command should have exited with tidied modules.

What did you see instead?

go: import "github.com/banzaicloud/pipeline/cluster" ->
	import "github.com/gin-gonic/gin/json": looping trying to add package

[bcmills]

CC @jayconrod

[jayconrod]

This error is happening because the package github.com/gin-gonic/gin/json was removed in newer versions of the module github.com/gin-gonic/gin (actually renamed to internal/json, but removed as far as everyone else is concerned). The "looping" error message comes up when we can't import the same package after more than one round of module loading.

So this is kind of working as intended (deleting a package is a breaking change), but we should report a more helpful error message.

You can work around this by removing imports of github.com/gin-gonic/gin/json in your project. If you still need it, you'll need to make a local copy of it.

[sagikazarmark]

Thanks! I actually did that and removed the import, so from my end the problem is resolved.

[bcmills]

Related: #29121 and #27102

[bcmills]

#27063 probably shares the underlying cause.

[gopherbot]

Change https://golang.org/cl/169720 mentions this issue: cmd/go: clarify error when package is removed in a module