cmd/link: -X fails with periods

[sigmonsays]

what used to work in go 1.7.3 no longer works in go 1.8

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

go version go1.8.3 linux/amd64

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

$ go env
GOARCH="amd64"
GOBIN=""
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/home/sig/gopath"
GORACE=""
GOROOT="/usr/local/go"
GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"
GCCGO="gccgo"
CC="gcc"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build896116486=/tmp/go-build"
CXX="g++"
CGO_ENABLED="1"
PKG_CONFIG="pkg-config"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"

What did you do?

run test_golink.sh (see below for script)

What did you expect to see?

"Version = 1.0.0"

What did you see instead?

"Version = dev"

test_golink.sh script

$ cat test_golink.sh

rm -rf gopath
mkdir gopath
cd gopath
export GOPATH=$HOME/gopath
mkdir -p src/mypackage.git/hello

cat << EOF > src/mypackage.git/config.go
package mypackage
var Version = "dev"
EOF

cat << EOF > src/mypackage.git/hello/main.go
package main

import (
"fmt"
"mypackage.git"
)

func main() {
fmt.Printf("version = %s\n", mypackage.Version)
}
EOF

go clean -i mypackage.git
go install -ldflags "-X mypackage%2egit.Version=1.0.0" mypackage.git mypackage.git/hello
go install mypackage.git/hello
./bin/hello

[ianlancetaylor]

What is the output of go tool nm bin/hello | grep Version ?

[hirochachacha]

Replace "%2e" with ".", then your problem will be solved.

[sigmonsays]

$ go tool nm bin/hello | grep Version
  4fa4e0 D mypackage%2egit.Version
  4b0a48 R mypackage%2egit.Version.str
  4fa510 D runtime.buildVersion
  516ba8 D runtime.processorVersionInfo

[sigmonsays]

It seems like replacing %2e with . works but I dont understand why. I can see how it works logically but am not sure if this is expected behavior given the ambiguity.

[ianlancetaylor]

This changed in 1.8 because of #16710. The new approach seems better, so I don't see any reason to revert to the old one. This should probably have been in the 1.8 release notes, but I guess we forgot.

Closing because I don't think there is anything to do.