cmd/go: allow -buildmode=pie with -race on macOS

[dan-smetana]

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

$ go version
go version go1.21.0 darwin/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='/Users/daniel/Library/Caches/go-build'
GOENV='/Users/daniel/Library/Application Support/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFLAGS=''
GOHOSTARCH='amd64'
GOHOSTOS='darwin'
GOINSECURE=''
GOMODCACHE='/Users/daniel/go/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='darwin'
GOPATH='/Users/daniel/go'
GOPRIVATE=''
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/Users/daniel/Downloads/go'
GOSUMDB='sum.golang.org'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/Users/daniel/Downloads/go/pkg/tool/darwin_amd64'
GOVCS=''
GOVERSION='go1.21.0'
GCCGO='gccgo'
GOAMD64='v1'
AR='ar'
CC='clang'
CXX='clang++'
CGO_ENABLED='1'
GOMOD='/dev/null'
GOWORK=''
CGO_CFLAGS='-O2 -g'
CGO_CPPFLAGS=''
CGO_CXXFLAGS='-O2 -g'
CGO_FFLAGS='-O2 -g'
CGO_LDFLAGS='-O2 -g'
PKG_CONFIG='pkg-config'
GOGCCFLAGS='-fPIC -arch x86_64 -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -ffile-prefix-map=/var/folders/f_/bzx32trj6ld4gd6_dcqlp1jh0000gn/T/go-build2514726154=/tmp/go-build -gno-record-gcc-switches -fno-common'

What did you do?

go build -buildmode=pie -race something.go

What did you expect to see?

The command to work without issues.

What did you see instead?

-buildmode=pie not supported when -race is enabled

Some more context:

On darwin/arm64 -buildmode=pie is fact required and is used by default. This means that even if I do go build -race something.go I still get a PIE binary. (see the code here: https://github.com/golang/go/blob/master/src/internal/platform/supported.go#L236)

It used to be that on macOS/amd64 I would not get a PIE binary, but as of 3 weeks ago that is not the case anymore: f7b4f02

This means that you always get a PIE binary when targeting macOS, even with the -race flag, yet if you explicitly specify that you want a PIE binary, it prints out an error. This is very confusing and should be fixed.

I suggest doing something like:

index cd99a33a21..a017b20e6b 100644
--- a/src/cmd/go/internal/work/init.go
+++ b/src/cmd/go/internal/work/init.go
@@ -264,8 +264,8 @@ func buildModeInit() {
 			pkgsFilter = oneMainPkg
 		}
 	case "pie":
-		if cfg.BuildRace {
-			base.Fatalf("-buildmode=pie not supported when -race is enabled")
+		if cfg.BuildRace && cfg.Goos != "darwin" {
+			base.Fatalf("-buildmode=pie not supported when -race is enabled (except on macOS)")
 		}
 		if gccgo {
 			codegenArg = "-fPIE"

(note that the patch above is for Go 1.20 so it may be slightly different for the latest version)

[seankhliao]

cc @golang/compiler

[gopherbot]

Change https://go.dev/cl/523475 mentions this issue: cmd/go: allow -buildmode=pie with -race on darwin