cmd/go mishandles build metadata separator

[mellis]

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

$ go version
go version go1.11 darwin/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="/Users/micellis/Library/Caches/go-build"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOOS="darwin"
GOPATH="/Users/micellis/go"
GOPROXY=""
GORACE=""
GOROOT="/usr/local/Cellar/go/1.11/libexec"
GOTMPDIR=""
GOTOOLDIR="/usr/local/Cellar/go/1.11/libexec/pkg/tool/darwin_amd64"
GCCGO="gccgo"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD=""
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/5n/cs1hx8q170v2741s2whxhc10pnl463/T/go-build108446644=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

go get example.com/foo/[email protected]+meta.sha256

Note the build metadata is not ignored when attempting to retrieve the info file.

What did you expect to see?

go: finding example.com/foo/bar v1.0.0
go: finding example.com/foo v1.0.0
go: finding example.com v1.0.0
go get example.com/foo/[email protected]+meta: unexpected status (http://localhost:8000/example.com/foo/bar/@v/v1.0.0.info): 404 File not found

What did you see instead?

go: finding example.com/foo/bar v1.0.0+meta.sha256
go: finding example.com/foo v1.0.0+meta.sha256
go: finding example.com v1.0.0+meta.sha256
go get example.com/foo/[email protected]+meta.sha256: unexpected status (http://localhost:8000/example.com/foo/bar/@v/v1.0.0+meta.sha256.info): 404 File not found

[mellis]

The issue is due to the internal/semver/semver.go package not recognizing the separator character '.' in the parseBuild function.

Have a small fix, just want to confirm this isn't expected (doesn't appear to be looking at the function and similar function parsePrerelease)

[gopherbot]

Change https://golang.org/cl/148835 mentions this issue: cmd/go: Fix parsing multiple build metadata

[thepudds]

@mellis The behavior here changed again recently in #31713.

It would be interesting to hear if you now see behavior that works for you if try tip. (An easy way to get tip is go get golang.org/dl/gotip && gotip download).

Also, did you have an example of a public repository where this was a problem, or was it a private repo where you first saw this as a problem?

[mellis]

I originally noticed the behaviour when experimenting with module support for our internal repositories and build system.

We've changed strategies since then though, so this particular issue isn't affecting us any more.