go: cmd/go: `go mod tidy` introduces ambiguous imports in pruned modules

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

/tmp/census3$ go version
go version devel go1.21-b60db8f7d9 Fri May 19 18:01:57 2023 +0000 linux/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='/usr/local/google/home/bcmills/.cache/go-build'
GOENV='/usr/local/google/home/bcmills/.config/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFLAGS=''
GOHOSTARCH='amd64'
GOHOSTOS='linux'
GOINSECURE=''
GOMODCACHE='/usr/local/google/home/bcmills/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='linux'
GOPATH='/usr/local/google/home/bcmills'
GOPRIVATE=''
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/usr/local/google/home/bcmills/go'
GOSUMDB='sum.golang.org'
GOTMPDIR=''
GOTOOLDIR='/usr/local/google/home/bcmills/go/pkg/tool/linux_amd64'
GOVCS=''
GOVERSION='devel go1.21-b60db8f7d9 Fri May 19 18:01:57 2023 +0000'
GCCGO='/usr/bin/gccgo'
GOAMD64='v1'
AR='ar'
CC='gcc'
CXX='c++'
CGO_ENABLED='1'
GOMOD='/tmp/census3/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-build1942413867=/tmp/go-build -gno-record-gcc-switches'

What did you do?

Clone vocdoni/census3@559b89d34e19824f0027a0724c136f9cac694673 and go mod tidy it twice:

$ git clone https://github.com/vocdoni/census3.git
$ git checkout 559b89d34e19824f0027a0724c136f9cac694673
$ go mod tidy
$ go mod tidy

What did you expect to see?

Both go mod tidy operations should succeed.

What did you see instead?

The first go mod tidy succeeds, but it removes a requirement needed to prevent an ambiguous import in a test dependency of a transitively-imported package, causing the second go mod tidy to fail:

/tmp/census3$ go mod tidy

/tmp/census3$ go mod tidy
github.com/vocdoni/census3/contracts/aragon/want imports
        github.com/ethereum/go-ethereum/accounts/abi imports
        github.com/ethereum/go-ethereum/crypto imports
        github.com/btcsuite/btcd/btcec/v2/ecdsa tested by
        github.com/btcsuite/btcd/btcec/v2/ecdsa.test imports
        github.com/btcsuite/btcd/chaincfg/chainhash: ambiguous import: found package github.com/btcsuite/btcd/chaincfg/chainhash in multiple modules:
        github.com/btcsuite/btcd v0.20.1-beta (/usr/local/google/home/bcmills/pkg/mod/github.com/btcsuite/btcd@v0.20.1-beta/chaincfg/chainhash)
        github.com/btcsuite/btcd/chaincfg/chainhash v1.0.2 (/usr/local/google/home/bcmills/pkg/mod/github.com/btcsuite/btcd/chaincfg/chainhash@v1.0.2)

(CC @matloob)

Example courtesy of @mvdan.

About this issue

Original URL
State: closed
Created a year ago
Reactions: 1
Comments: 17 (7 by maintainers)

Commits related to this issue

cmd/go: add a test that reproduces an unstable 'go mod tidy' For #60313. Change-Id: I76e48f52341e9962de9b809741a677d61baae6a9 Reviewed-on: https://go-review.googlesource.com/c/go/+/496518 Reviewed-b... — committed to golang/go by bcmills a year ago
cmd/go/internal/modload: address comment and test issues from CL 496635 Michael noticed some minor issues in backports of CL 496635. Those issues have been addressed in the backport CLs; this change ... — committed to golang/go by bcmills a year ago
[release-branch.go1.20] cmd/go: retain extra roots to disambiguate imports in 'go mod tidy' We don't normally keep explicit requirements for test dependencies of packages loaded from other modules wh... — committed to golang/go by bcmills a year ago
[release-branch.go1.19] cmd/go: retain extra roots to disambiguate imports in 'go mod tidy' We don't normally keep explicit requirements for test dependencies of packages loaded from other modules wh... — committed to golang/go by bcmills a year ago

Most upvoted comments

go get github.com/btcsuite/btcd/chaincfg/chainhash works now as chainhash just upgraded to v1.0.2.

go: upgraded github.com/btcsuite/btcd/chaincfg/chainhash v1.0.1 => v1.0.2

tranvictor on Aug 2, 2023

@costela, consumers of my.private.package may still need to go get a specific module to disambiguate when they first add the dependency. #27899 is the issue for that more general problem.

bcmills on Jul 19, 2023