Go: cmd/go: accept tags of the form X.Y.Z (without leading 'v') as semantic versions

[tamalsaha]

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

$ go1.13beta1 version
go version go1.13beta1 linux/amd64
$ go version
go version go1.12.6 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


GOARCH="amd64"

GOBIN=""

GOCACHE="/home/tamal/.cache/go-build"

GOEXE=""

GOFLAGS=""

GOHOSTARCH="amd64"

GOHOSTOS="linux"

GOOS="linux"

GOPATH="/home/tamal/go"

GOPROXY=""

GORACE=""

GOROOT="/usr/local/go"

GOTMPDIR=""

GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"

GCCGO="gccgo"

CC="gcc"

CXX="g++"

CGO_ENABLED="1"

GOMOD="/dev/null"

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-build803673677=/tmp/go-build -gno-record-gcc-switches"

What did you do?

$ go1.13beta1 get github.com/kubedb/[email protected]
go: finding github.com/kubedb/apimachinery v0.11.0
go: finding github.com/kubedb/apimachinery v0.11.0
go: finding github.com v0.11.0
go: finding github.com/kubedb v0.11.0
go get github.com/kubedb/[email protected]: unknown revision v0.11.0

$ go1.13beta1 get github.com/kubedb/[email protected]
go: finding github.com/kubedb/apimachinery 0.11.0

We use the git tag also as the Docker image tag. I like kubedb/operator:1.0.0 (without v) over kubedb/operator:v1.0.0. So, we went with that. Tools like glide, dep will automatically handle the presence or absence of v. But go mod does not do that.

What did you expect to see?

My question is can go mod automatically search for both of these prefixes?

What did you see instead?

[bcmills]

See previously #30146.

[bcmills]

CC @jayconrod

To reiterate from that discussion: the difference is mainly aesthetic and relatively arbitrary. Absent a compelling need otherwise, Go usually resolves aesthetic differences by picking one to use consistently (think of gofmt), not supporting both.

[jayconrod]

+1 to not supporting this. It's unfortunate that different systems have different standards for this, but supporting both formats would lead to ambiguity and confusion. For example, both vX.Y.Z and X.Y.Z might exist and point to different commits.

go release should probably warn against creating such a version accidentally in the future.

[bcmills]

supporting both formats would lead to ambiguity and confusion

Note that there is a similar problem for build metadata, which we resolve (in Go 1.13) by resolving to a unique pseudo-version _derived from_ the tagged version.

[mattharr-is]

i think the ironic part about all of this is this bit in the semver.org FAQ
https://semver.org/#is-v123-a-semantic-version
In my case, we have an existing build system that handles repo versioning and tagging for us, using standard semver format (no v prefix). When one reads the go module docs about how it all works with a "standard semver format", and then seeing that it's not actually standard semver format, is a bit confusing. It also requires retooling some build processes that actually do follow the standard.

[alexellis]

+1 cc @LucasRoesler @Waterdrips @stefanprodan - we were all hit by this today, we use semver but "the valid way" i.e. without a "v" prefix and dep was fine for us - we could have a proper tag in our dependency file, but now we're stuck with lots of v0.0.0 SHA in all our code. Was hoping that moving to go modules was going to be a pleasant, pain-free upgrade.

We don't want to change the tags if we can avoid it because semver itself recommends against no prefix and also, we rely on the numbering for Docker images.

[gudvinr]

We consistently use unprefixed tags X.Y.Z versions across all of the internal projects. Some of them are shared between projects and not every project is written in Go. This is really annoying requirement because it is not language-related but still ruining existing workflow.

Arguments like "you may have both prefixed and unprefixed tags in repo" is quite silly because if you _do have_ such tags in your repo you probably have a bigger problem with your VCS already.

You may as well have very old commit tagged by higher version number and this also doesn't look right. You may have tags with same version and different metadata which is not used in version comparison too.

[gudvinr]

the difference is mainly aesthetic and relatively arbitrary.

@bcmills This is not aesthetic for projects that existed outside of Google (and companies that use prefixed tags) before introduction of go modules. It is messing up with build process.

Reference to gofmt also seems wrong here. gofmt is tool for Go language only and can't interfere with anything outside Go ecosystem, but requirement on git tags leads to unwanted changes.

[taiidani]

Agreeing with the above. My company is highly polyglot among multiple languages but our release and tagging automation is reused between them. We implemented this logic using the "correct" semver way without the "v" prefix.

It will be an extremely bitter pill to swallow if we have to update our automation and [ideally] re-tag all of our repositories to add the "v" prefix because of one languages' requirement.

[MCBrandenburg]

I'm in the a similar boat to @taiidani, trying to get a company to prefix with their already automated process with a v to satisfy the case for go https://github.com/FusionAuth/go-client/pull/32

[mieubrisse]

Another +1 - we started our project using X.Y.Z the official semver way, but consumers of our library are confused as to why the go.mod file ends up as v0.0.0-YYYYMMDDSSSSS-abcd1234