sync: fix go1.26 build constraints

[zchee]

Fix compile error on go1.26rc1.
There is no error in pkg/sync/runtime_spinning_go126_amd64.s, but pkg/sync/runtime_spinning_go125_amd64.s is blocking go1.26, so fix it as well.

• gvisor/pkg/sync/runtime_spinning_go125_amd64.s

  Line 17 in 9f2192b

  //go:build amd64 && go1.25 && !go1.26

go env output

AR='/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ar'
CC='/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang'
CGO_CFLAGS='-O2 -g'
CGO_CPPFLAGS=''
CGO_CXXFLAGS='-O2 -g'
CGO_ENABLED='1'
CGO_FFLAGS='-O2 -g'
CGO_LDFLAGS='-O2 -g'
CXX='/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang++'
GCCGO='gccgo'
GO111MODULE=''
GOARCH='arm64'
GOARM64='v8.0'
GOAUTH='netrc'
GOBIN=''
GOCACHE='/Users/zchee/.cache/go/go-build'
GOCACHEPROG=''
GODEBUG=''
GOENV='/Users/zchee/.config/go/env/env'
GOEXE=''
GOEXPERIMENT='loopvar,newinliner,jsonv2,greenteagc'
GOFIPS140='latest'
GOFLAGS=''
GOGCCFLAGS='-fPIC -arch arm64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -ffile-prefix-map=/var/folders/dp/89wwdp754235m6jmdzj7p5lm0000gn/T/go-build365494810=/tmp/go-build -gno-record-gcc-switches -fno-common'
GOHOSTARCH='arm64'
GOHOSTOS='darwin'
GOINSECURE=''
GOMOD='/Users/zchee/go/src/gvisor.dev/gvisor/go.mod'
GOMODCACHE='/Users/zchee/go/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='darwin'
GOPATH='/Users/zchee/go'
GOPRIVATE=''
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/Users/zchee/sdk/go1.26rc1'
GOSUMDB='sum.golang.org'
GOTELEMETRY='on'
GOTELEMETRYDIR='/Users/zchee/Library/Application Support/go/telemetry'
GOTMPDIR=''
GOTOOLCHAIN='go1.26rc1+auto'
GOTOOLDIR='/Users/zchee/sdk/go1.26rc1/pkg/tool/darwin_arm64'
GOVCS=''
GOVERSION='go1.26rc1'
GOWORK=''
PKG_CONFIG='pkgconf'

$ git rev-parse --abbrev-ref HEAD
go
$ git rev-parse HEAD
9f2192bea5ab6eeec7cf59c2a0f609fffbadbcca

# my local machine is darwin/arm64

$ GOOS=linux GOARCH=amd64 go1.26rc1 build -o /dev/null -v ./sync
gvisor.dev/gvisor/pkg/sync
# gvisor.dev/gvisor/pkg/sync
sync/runtime_constants_go126.go:22:2: WaitReasonSelect redeclared in this block
	sync/runtime_constants_go125.go:22:2: other declaration of WaitReasonSelect
sync/runtime_constants_go126.go:23:2: WaitReasonChanReceive redeclared in this block
	sync/runtime_constants_go125.go:23:2: other declaration of WaitReasonChanReceive
sync/runtime_constants_go126.go:24:2: WaitReasonSemacquire redeclared in this block
	sync/runtime_constants_go125.go:24:2: other declaration of WaitReasonSemacquire

[tamird]

I think there's also a nonsensical constraint here:

gvisor/pkg/sync/runtime_spinning_amd64.s

Line 17 in 466fd4e

//go:build amd64 && !go1.25 && !go1.26

since go1.26 is true iff go1.25 is true, so logical AND there is pointless.

[zchee]

@tamird

I think there's also a nonsensical constraint here:

yep, I'd overlooked. I'll fix as well later.

[zchee]

@ayushr2 @tamird PTAL

[zchee]

gentle ping

[ayushr2]

Sorry for the back and forth regarding comments. Was having trouble importing this change. It seems that we have a Copybara transformation which requires that go1.25 be accompanied with // https://go.dev/cl/669235 (1.25) adds a new schedt field prior to nmspinning. and go1.26 be accompanied with // https://go.dev/cl/714800 (1.26) changes size of the schedt.midle field.

Even when using !go1.26, we need the 1.26 comment. If you look, this is the rule that the current codebase is following. I don't agree with it, but defining complex copybara transformations is tough. The transformation currently doesn't understand "don't add comment for !go1.xx".

Could you update your PR with this rule? I will also leave in line comments to clarify more. Without this, the copybara transformations are failing.

[zchee]

okay and np! I'm not Googler but I know Copybara is difficult to manage (I heard this from the author of the CUE language), and I'll fix it soon.

[zchee]

@ayushr2 is thiss changes are correct?

• 5dcd8fe (#12397)

---

If correctly and need to squash, I'll do that.

[ayushr2]

I think this comment is wrong, should be // https://go.dev/cl/714800 (1.26) changes size of the schedt.midle field.

[ayushr2]

Could you also squash your commits.