cmd/go: 'go test -race' fails with 'relocation target __popcountdi2 not defined' when GCC not installed

[candlerb]

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

$ go version
go version go1.19.3 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=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/brian/.cache/go-build"
GOENV="/home/brian/.config/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GOMODCACHE="/home/brian/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="/home/brian/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"
GOVCS=""
GOVERSION="go1.19.3"
GCCGO="gccgo"
GOAMD64="v1"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD="/home/brian/z/go.mod"
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 -fno-caret-diagnostics -Qunused-arguments -Wl,--no-gc-sections -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build3661110452=/tmp/go-build -gno-record-gcc-switches"

NOTE: this is running on an ubuntu-minimal lxd container (22.04.1) which does not have gcc installed.

What did you do?

$ cat go.mod
module example.com/test

go 1.19

$ cat main_test.go
package main

$ go test -race . -vet=off
# example.com/test.test
runtime/race(.text): relocation target __popcountdi2 not defined
FAIL	example.com/test [build failed]
FAIL

There is a separate but possibly related problem #56755, which is why -vet=off is required. Without it:

$ go test -race .
# runtime/cgo
cgo: C compiler "gcc" not found: exec: "gcc": executable file not found in $PATH
FAIL	example.com/test [build failed]
FAIL

What did you expect to see?

Successful test execution.

Or: documentation that the race detector does not work without GCC. I checked here and here.

What did you see instead?

See above.

Possibly relates to #3261 (old ticket, but it does reference missing __popcountdi2 explicitly)

[ianlancetaylor]

In general using -race does require that cgo be enabled, which does require that GCC be available. This is #6508. This requirement is documented at https://go.dev/doc/articles/race_detector#Requirements, but looking at that I see that it is unclear unless you understand that cgo requires a C compiler. I'll send a patch.

[gopherbot]

Change https://go.dev/cl/453435 mentions this issue: _content/doc/articles/race_detector: cgo requires a C compiler