cmd/dist: toolchain3 fails in external linking mode due to stale targets

[erifan]

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

$ go version
tip

What did you do?

$ GO_LDFLAGS="-linkmode=external" ./make.bash

What did you expect to see?

Successfully build go

What did you see instead?

$ GO_LDFLAGS="-linkmode=external" ./make.bash
Building Go cmd/dist using /usr/lib/go-1.13. (go1.13.8 linux/amd64)
Building Go toolchain1 using /usr/lib/go-1.13.
Building Go bootstrap cmd/go (go_bootstrap) using Go toolchain1.
Building Go toolchain2 using go_bootstrap and Go toolchain1.
Building Go toolchain3 using go_bootstrap and Go toolchain2.
HASH[moduleIndex]
HASH[moduleIndex]: "devel go1.19-160414ca6a Tue Jun 28 21:01:39 2022 +0000"
HASH[moduleIndex]: "package devel go1.19-160414ca6a Tue Jun 28 21:01:39 2022 +0000 go index v0 /home/erifan02/go-master/src/runtime/internal/sys\n"
......
runtime/internal/sys true
go tool dist: unexpected stale targets reported by /home/erifan02/go-master/pkg/tool/linux_amd64/go_bootstrap list -gcflags="" -ldflags="-linkmode=external" for [cmd/asm cmd/cgo cmd/compile cmd/link runtime/internal/sys] (consider rerunning with GOMAXPROCS=1 GODEBUG=gocachehash=1):
STALE cmd/asm: stale dependency: internal/goarch
STALE cmd/cgo: stale dependency: internal/goarch
STALE cmd/compile: stale dependency: internal/goarch
STALE cmd/link: stale dependency: internal/goarch
STALE runtime/internal/sys: stale dependency: internal/goarch

[bcmills]

Please fill out the complete issue template — what is the output of go env in your environment from a non-external build?

In addition, what toolchain and version are you using for the external linker? (Does this reproduce with both gcc and clang toolchains, or just one of the two, or just one specific version?)

[erifan]

$ go env

GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/erifan02/.cache/go-build"
GOENV="/home/erifan02/.config/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GOMODCACHE="/home/erifan02/gopath/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="/home/erifan02/gopath"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/home/erifan02/go-master"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/home/erifan02/go-master/pkg/tool/linux_amd64"
GOVCS=""
GOVERSION="devel go1.19-160414ca6a Tue Jun 28 21:01:39 2022 +0000"
GCCGO="gccgo"
GOAMD64="v1"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD="/dev/null"
GOWORK=""
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 -Wl,--no-gc-sections -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build3057986183=/tmp/go-build -gno-record-gcc-switches"

$ gcc -v

Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/9/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none:hsa
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 9.4.0-1ubuntu1~20.04.1' --with-bugurl=file:///usr/share/doc/gcc-9/README.Bugs --enable-languages=c,ada,c++,go,brig,d,fortran,objc,obj-c++,gm2 --prefix=/usr --with-gcc-major-version-only --program-suffix=-9 --program-prefix=x86_64-linux-gnu- --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-nls --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-gnu-unique-object --disable-vtable-verify --enable-plugin --enable-default-pie --with-system-zlib --with-target-system-zlib=auto --enable-objc-gc=auto --enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic --enable-offload-targets=nvptx-none=/build/gcc-9-Av3uEd/gcc-9-9.4.0/debian/tmp-nvptx/usr,hsa --without-cuda-driver --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 9.4.0 (Ubuntu 9.4.0-1ubuntu1~20.04.1)

$ clang -v

Apple clang version 12.0.0 (clang-1200.0.32.29)
Target: arm64-apple-darwin20.6.0
Thread model: posix
InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin

I tried linux/amd64, linux/arm64, macos/arm64, gcc, clang, all of them will report this error.

[bcmills]

@erifan, I suspect that this may have been fixed by the work for reproducible toolchain builds in Go 1.21. Does it still reproduce for you?

[erifan]

@bcmills The error has changed to another one:

$ GO_LDFLAGS="-linkmode=external" ./make.bash
Building Go cmd/dist using /home/erifan02/go1.21.0. (go1.21.0 linux/amd64)
Building Go toolchain1 using /home/erifan02/go1.21.0.
Building Go bootstrap cmd/go (go_bootstrap) using Go toolchain1.
Building Go toolchain2 using go_bootstrap and Go toolchain1.
-linkmode=external requires external (cgo) linking, but cgo is not enabled
-linkmode=external requires external (cgo) linking, but cgo is not enabled
-linkmode=external requires external (cgo) linking, but cgo is not enabled
-linkmode=external requires external (cgo) linking, but cgo is not enabled
go tool dist: FAILED: /home/erifan02/go-master/pkg/tool/linux_amd64/go_bootstrap install -ldflags=all=-linkmode=external -pgo=off cmd/asm cmd/cgo cmd/compile cmd/link: exit status 1

[bcmills]

Aha! That one seems like a reasonable failure mode to me. You have explicitly set GO_LDFLAGS to require external linking, but make.bash builds the toolchain with CGO_ENABLED=0 in order to provide reproducible binaries (see cmd/dist.toolenv), and those two goals are incompatible.

If you really want to build a cgo-enabled toolchain, you can run the default make.bash to bootstrap, and then go install cmd -ldflags=-linkmode=external to overwrite the installed installed toolchain binaries with cgo-enabled, externally-linked versions.