go: cmd/go: duplicate symbols when including two main packages in -coverpkg in module mode

Note that I am not sure if this is a bug or expected behaviour, only that this does not happen in the latest stable 1.11 release and does on 1.12rc1.

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

$ go version
go version go1.12rc1 linux/amd64

Does this issue reproduce with the latest release?

Not the latest stable release (1.11.5)

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

go env Output

$ go env
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/lazer/.cache/go-build"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/home/lazer/go"
GOPROXY=""
GORACE=""
GOROOT="/home/lazer/sdk/go1.12rc1"
GOTMPDIR=""
GOTOOLDIR="/home/lazer/sdk/go1.12rc1/pkg/tool/linux_amd64"
GCCGO="gccgo"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD="/home/lazer/Dev/gosnaillife/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-build721704492=/tmp/go-build -gno-record-gcc-switches"

What did you do?

I ran the following command:

go1.12rc1 test -race -v -coverpkg gitlab.com/drakonka/gosnaillife/cmd/snaillifecli,gitlab.com/drakonka/gosnaillife/cmd/snaillifesrv, -coverprofile allcoverage-rc.out ./...

Both of the above are main packages producing two binaries.

What did you expect to see?

I expected the tests to run and pass, with coverage output, as they do on Go 1.11.5

What did you see instead?

The following error:

2019/02/24 11:39:04 duplicate symbol runtime/debug.modinfo (types 30 and 30) in gitlab.com/drakonka/gosnaillife/cmd/snaillifecli and $WORK/b293/_pkg_.a(_go_.o)

I run Go RC and Go 1.11 side by side as part of my CI, which is how I noticed this issue. I am able to reproduce it locally as well. Full logs for the successful run of Go 1.11 and the failure run of Go 1.12rc1 can be found here:

About this issue

Original URL
State: closed
Created 5 years ago
Reactions: 3
Comments: 25 (17 by maintainers)

Commits related to this issue

Removed one of the examples - can't have 2 main packages otherwise go cov fails https://github.com/golang/go/issues/30374 — committed to peterzen/goresolver by peterzen 5 years ago

Most upvoted comments

@gopherbot, please backport to 1.12. This is a significant regression from GOPATH mode and the fix is straightforward.

bcmills on Mar 8, 2019

I’ve been doing it like this:

CVPKG=$(go list ./... | grep -v -e mocks -e snaillifecli -e snaillifesrv | tr '\n' ',') 

go test -race -v -coverpkg $CVPKG -coverprofile allcoverage-stable.out ./...

lshulyay on Mar 2, 2019

Change https://golang.org/cl/164877 mentions this issue: cmd/go: avoid link errors when -coverpkg covers main packages

gopherbot on Mar 1, 2019

Given that we do not currently merge coverage profiles from multiple processes (#28235), I’m not sure why you would want to include two different main packages in the same -coverpkg argument (except, perhaps, to simplify the patterns passed to -coverpkg).

The workaround for now is to include at most one main package in the -coverpkg arguments, or to run coverage in GOPATH mode.

bcmills on Feb 25, 2019

I found the same regression just a few days ago, but hadn’t filed an issue yet. This is impeding my daily development, and I’d consider it a regression introduced in 1.12.

The 1.12 release will be out any day now though, so it’s probably more realistic to target a backport to 1.12.1. /cc @bcmills @ianlancetaylor @hyangah since this very likely relates to the recent modinfo changes in the cycle.

mvdan on Feb 25, 2019