cmd/go: allow combining -race and -buildmode=PIE again

[aktau]

Go version

Go 1.26-dev

Output of go env in your module/workspace:

N/A

What did you do?

cc @cherrymui

The following is not supported:

$ go build -race -buildmode=pie hello.go 
-buildmode=pie not supported when -race is enabled on linux/amd64

What did you see happen?

The go tool does not allow it.

What did you expect to see?

It probably should be allowed.

For reference, it was disabled in https://go.dev/cl/41333 for #20038. Back then (in 2017), @dvyukov stated that the race detector did not support PIE. I believe this has changed:

• We've run internal tests (using raw go tool compile and go tool link) which indicate that this works now (on linux/amd64).
• Platforms that default to PIE, like Darwin, have allowed PIE+race since https://go.dev/cl/523475 (2023, cmd/go: allow -buildmode=pie with -race on macOS #62318).

[gabyhelp]

Related Issues

• cmd/go: allow -buildmode=pie with -race on macOS #62318 (closed)
• runtime: go compiler with PIE enabled by default race segv #31384 (closed)
• cmd/link: ld: warning: -no_pie is deprecated in new macOS version #55871 (closed)
• cmd/go: building with -buildmode=pie on windows/arm64 fails #56872 (closed)

Related Code Changes

• cmd/go: reject use of PIE with -race
• cmd/go: reject buildmode=pie when -race is enabled
• cmd/go: allow -buildmode=pie with -race on darwin
• cmd/link: explicitly disable PIE for windows/amd64 -race mode
• cmd/go: default to "exe" build mode for windows -race
• cmd/dist: add -buildmode flag for testing PIE

_{(Emoji vote if this was helpful or unhelpful; more detailed feedback welcome in this discussion.)}