go/build: BuildTags should reject tags with the same name as a known os or arch

[perillo]

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

$ go version
go version go1.16.3 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="on"
GOARCH="amd64"
GOBIN="/home/manlio/.local/bin"
GOCACHE="/home/manlio/.cache/go-build"
GOENV="/home/manlio/.config/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE="*.local"
GOMODCACHE="/home/manlio/.local/lib/go/pkg/mod"
GONOPROXY=""
GONOSUMDB="*.local"
GOOS="linux"
GOPATH="/home/manlio/.local/lib/go:/home/manlio/src/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/lib/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/lib/go/pkg/tool/linux_amd64"
GOVCS=""
GOVERSION="go1.16.3"
GCCGO="gccgo"
AR="ar"
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-build2654897084=/tmp/go-build -gno-record-gcc-switches"
GOROOT/bin/go version: go version go1.16.3 linux/amd64
GOROOT/bin/go tool compile -V: compile version go1.16.3
uname -sr: Linux 5.11.11-arch1-1
/usr/lib/libc.so.6: GNU C Library (GNU libc) release release version 2.33.
gdb --version: GNU gdb (GDB) 10.1

What did you do?

go vet -tags=windows on a Linux host.

What did you expect to see?

An error, explaining that "windows" should not be used as a build tag.

What did you see instead?

# runtime/internal/sys
/usr/lib/go/src/runtime/internal/sys/zgoos_windows.go:7:7: GOOS redeclared in this block
	previous declaration at /usr/lib/go/src/runtime/internal/sys/zgoos_linux.go:8:14
/usr/lib/go/src/runtime/internal/sys/zgoos_windows.go:9:7: GoosAix redeclared in this block
	previous declaration at /usr/lib/go/src/runtime/internal/sys/zgoos_linux.go:10:17
/usr/lib/go/src/runtime/internal/sys/zgoos_windows.go:10:7: GoosAndroid redeclared in this block
	previous declaration at /usr/lib/go/src/runtime/internal/sys/zgoos_linux.go:11:21
/usr/lib/go/src/runtime/internal/sys/zgoos_windows.go:11:7: GoosDarwin redeclared in this block
	previous declaration at /usr/lib/go/src/runtime/internal/sys/zgoos_linux.go:12:20
/usr/lib/go/src/runtime/internal/sys/zgoos_windows.go:12:7: GoosDragonfly redeclared in this block
	previous declaration at /usr/lib/go/src/runtime/internal/sys/zgoos_linux.go:13:23
/usr/lib/go/src/runtime/internal/sys/zgoos_windows.go:13:7: GoosFreebsd redeclared in this block
	previous declaration at /usr/lib/go/src/runtime/internal/sys/zgoos_linux.go:14:21
/usr/lib/go/src/runtime/internal/sys/zgoos_windows.go:14:7: GoosHurd redeclared in this block
	previous declaration at /usr/lib/go/src/runtime/internal/sys/zgoos_linux.go:15:18
/usr/lib/go/src/runtime/internal/sys/zgoos_windows.go:15:7: GoosIllumos redeclared in this block
	previous declaration at /usr/lib/go/src/runtime/internal/sys/zgoos_linux.go:16:21
/usr/lib/go/src/runtime/internal/sys/zgoos_windows.go:16:7: GoosIos redeclared in this block
	previous declaration at /usr/lib/go/src/runtime/internal/sys/zgoos_linux.go:17:17
/usr/lib/go/src/runtime/internal/sys/zgoos_windows.go:17:7: GoosJs redeclared in this block
	previous declaration at /usr/lib/go/src/runtime/internal/sys/zgoos_linux.go:18:16
/usr/lib/go/src/runtime/internal/sys/zgoos_windows.go:17:7: too many errors

A similar error is reported when a different arch is specified as a build tag.

Is there a reason why a build tag with the same name of an os or arch is not rejected?

Thanks.

[mknyszek]

CC @rsc via https://dev.golang.org/owners.

[qdm12]

I obtain a very similar error but on Windows.

$ go version
set GO111MODULE=
set GOARCH=amd64
set GOBIN=
set GOCACHE=C:\Users\user\AppData\Local\go-build
set GOENV=C:\Users\user\AppData\Roaming\go\env
set GOEXE=.exe
set GOEXPERIMENT=
set GOFLAGS=
set GOHOSTARCH=amd64
set GOHOSTOS=windows
set GOINSECURE=
set GOMODCACHE=C:\Users\user\go\pkg\mod
set GONOPROXY=
set GONOSUMDB=
set GOOS=windows
set GOPATH=C:\Users\user\go
set GOPRIVATE=
set GOPROXY=https://proxy.golang.org,direct
set GOROOT=C:\Program Files\Go
set GOSUMDB=sum.golang.org
set GOTMPDIR=
set GOTOOLDIR=C:\Program Files\Go\pkg\tool\windows_amd64
set GOVCS=
set GOVERSION=go1.17
set GCCGO=gccgo
set AR=ar
set CC=gcc
set CXX=g++
set CGO_ENABLED=1
set GOMOD=E:\somerepo\go.mod
set CGO_CFLAGS=-g -O2
set CGO_CPPFLAGS=
set CGO_CXXFLAGS=-g -O2
set CGO_FFLAGS=-g -O2
set CGO_LDFLAGS=-g -O2
set PKG_CONFIG=pkg-config
set GOGCCFLAGS=-m64 -mthreads -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=C:\Users\user\AppData\Local\Temp\go-build2520574871=/tmp/go-build -gno-record-gcc-switches

Steps to reproduce:

1. Clone some repository using syscall, in my case:

   git clone https://github.com/qdm12/gluetun.git .

2. Run tests with go test -tags=linux ./...

Errors shown as:

C:\Program Files\Go\src\runtime\internal\sys\zgoos_windows.go:8:7: GOOS redeclared in this block
        C:\Program Files\Go\src\runtime\internal\sys\zgoos_linux.go:8:14: previous declaration
C:\Program Files\Go\src\runtime\internal\sys\zgoos_windows.go:10:7: GoosAix redeclared in this block
        C:\Program Files\Go\src\runtime\internal\sys\zgoos_linux.go:10:17: previous declaration
C:\Program Files\Go\src\runtime\internal\sys\zgoos_windows.go:11:7: GoosAndroid redeclared in this block
        C:\Program Files\Go\src\runtime\internal\sys\zgoos_linux.go:11:21: previous declaration
C:\Program Files\Go\src\runtime\internal\sys\zgoos_windows.go:12:7: GoosDarwin redeclared in this block
        C:\Program Files\Go\src\runtime\internal\sys\zgoos_linux.go:12:20: previous declaration
C:\Program Files\Go\src\runtime\internal\sys\zgoos_windows.go:13:7: GoosDragonfly redeclared in this block
        C:\Program Files\Go\src\runtime\internal\sys\zgoos_linux.go:13:23: previous declaration
C:\Program Files\Go\src\runtime\internal\sys\zgoos_windows.go:14:7: GoosFreebsd redeclared in this block
        C:\Program Files\Go\src\runtime\internal\sys\zgoos_linux.go:14:21: previous declaration
C:\Program Files\Go\src\runtime\internal\sys\zgoos_windows.go:15:7: GoosHurd redeclared in this block
        C:\Program Files\Go\src\runtime\internal\sys\zgoos_linux.go:15:18: previous declaration
C:\Program Files\Go\src\runtime\internal\sys\zgoos_windows.go:16:7: GoosIllumos redeclared in this block
        C:\Program Files\Go\src\runtime\internal\sys\zgoos_linux.go:16:21: previous declaration
C:\Program Files\Go\src\runtime\internal\sys\zgoos_windows.go:17:7: GoosIos redeclared in this block
        C:\Program Files\Go\src\runtime\internal\sys\zgoos_linux.go:17:17: previous declaration
C:\Program Files\Go\src\runtime\internal\sys\zgoos_windows.go:18:7: GoosJs redeclared in this block
        C:\Program Files\Go\src\runtime\internal\sys\zgoos_linux.go:18:16: previous declaration
C:\Program Files\Go\src\runtime\internal\sys\zgoos_windows.go:18:7: too many errors

Followed by a few [build failed] for each sub-package of the repository

[ross-spencer]

Golang 1.20.2 here, tried the same lib as above after seeing it on another repo.

go test -tags=windows ./...

go: downloading golang.zx2c4.com/wintun v0.0.0-20211104114900-415007cec224
# internal/goos
/usr/local/go/src/internal/goos/zgoos_windows.go:7:7: GOOS redeclared in this block
	/usr/local/go/src/internal/goos/zgoos_linux.go:7:7: other declaration of GOOS
/usr/local/go/src/internal/goos/zgoos_windows.go:9:7: IsAix redeclared in this block
	/usr/local/go/src/internal/goos/zgoos_linux.go:9:7: other declaration of IsAix
/usr/local/go/src/internal/goos/zgoos_windows.go:10:7: IsAndroid redeclared in this block
	/usr/local/go/src/internal/goos/zgoos_linux.go:10:7: other declaration of IsAndroid
/usr/local/go/src/internal/goos/zgoos_windows.go:11:7: IsDarwin redeclared in this block
	/usr/local/go/src/internal/goos/zgoos_linux.go:11:7: other declaration of IsDarwin
/usr/local/go/src/internal/goos/zgoos_windows.go:12:7: IsDragonfly redeclared in this block
	/usr/local/go/src/internal/goos/zgoos_linux.go:12:7: other declaration of IsDragonfly
/usr/local/go/src/internal/goos/zgoos_windows.go:13:7: IsFreebsd redeclared in this block
	/usr/local/go/src/internal/goos/zgoos_linux.go:13:7: other declaration of IsFreebsd
/usr/local/go/src/internal/goos/zgoos_windows.go:14:7: IsHurd redeclared in this block
	/usr/local/go/src/internal/goos/zgoos_linux.go:14:7: other declaration of IsHurd
/usr/local/go/src/internal/goos/zgoos_windows.go:15:7: IsIllumos redeclared in this block
	/usr/local/go/src/internal/goos/zgoos_linux.go:15:7: other declaration of IsIllumos
/usr/local/go/src/internal/goos/zgoos_windows.go:16:7: IsIos redeclared in this block
	/usr/local/go/src/internal/goos/zgoos_linux.go:16:7: other declaration of IsIos
/usr/local/go/src/internal/goos/zgoos_windows.go:17:7: IsJs redeclared in this block
	/usr/local/go/src/internal/goos/zgoos_linux.go:17:7: other declaration of IsJs
/usr/local/go/src/internal/goos/zgoos_windows.go:17:7: too many errors
FAIL	github.com/qdm12/gluetun/internal/configuration/settings [build failed]
?   	github.com/qdm12/gluetun/internal/constants/openvpn	[no test files]
FAIL	github.com/qdm12/gluetun/internal/configuration/sources/env [build failed]
?   	github.com/qdm12/gluetun/internal/constants/vpn	[no test files]
FAIL	github.com/qdm12/gluetun/internal/constants/providers [build failed]
FAIL	github.com/qdm12/gluetun/internal/dns [build failed]
FAIL	github.com/qdm12/gluetun/internal/firewall [build failed]
FAIL	github.com/qdm12/gluetun/internal/healthcheck [build failed]
FAIL	github.com/qdm12/gluetun/internal/httpserver [build failed]
FAIL	github.com/qdm12/gluetun/internal/models [build failed]
FAIL	github.com/qdm12/gluetun/internal/netlink [build failed]
FAIL	github.com/qdm12/gluetun/internal/openvpn [build failed]
FAIL	github.com/qdm12/gluetun/internal/openvpn/extract [build failed]
FAIL	github.com/qdm12/gluetun/internal/pprof [build failed]
FAIL	github.com/qdm12/gluetun/internal/provider/common [build failed]
FAIL	github.com/qdm12/gluetun/internal/provider/custom [build failed]
FAIL	github.com/qdm12/gluetun/internal/provider/expressvpn [build failed]
?   	github.com/qdm12/gluetun/internal/provider/privateinternetaccess/presets	[no test files]
FAIL	github.com/qdm12/gluetun/internal/provider/ipvanish/updater [build failed]
FAIL	github.com/qdm12/gluetun/internal/provider/ivpn [build failed]
FAIL	github.com/qdm12/gluetun/internal/provider/ivpn/updater [build failed]
?   	github.com/qdm12/gluetun/internal/provider/surfshark/servers	[no test files]
FAIL	github.com/qdm12/gluetun/internal/provider/mullvad [build failed]
FAIL	github.com/qdm12/gluetun/internal/provider/mullvad/updater [build failed]
FAIL	github.com/qdm12/gluetun/internal/provider/privateinternetaccess [build failed]
FAIL	github.com/qdm12/gluetun/internal/provider/slickvpn/updater [build failed]
FAIL	github.com/qdm12/gluetun/internal/provider/surfshark/updater [build failed]
FAIL	github.com/qdm12/gluetun/internal/provider/utils [build failed]
FAIL	github.com/qdm12/gluetun/internal/provider/vpnsecure/updater [build failed]
FAIL	github.com/qdm12/gluetun/internal/provider/wevpn [build failed]
FAIL	github.com/qdm12/gluetun/internal/provider/windscribe [build failed]
FAIL	github.com/qdm12/gluetun/internal/routing [build failed]
FAIL	github.com/qdm12/gluetun/internal/storage [build failed]
FAIL	github.com/qdm12/gluetun/internal/tun [build failed]
FAIL	github.com/qdm12/gluetun/internal/updater/html [build failed]
FAIL	github.com/qdm12/gluetun/internal/updater/resolver [build failed]
FAIL	github.com/qdm12/gluetun/internal/wireguard [build failed]
FAIL