runtime/race: building for iOS, but linking in object file built for macOS

[eliasnaur]

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

Happens on tip on the Corellium iOS builders that have recently upgraded to iOS 14.6 while debugging #35851.

Does this issue reproduce with the latest release?

Yes

What operating system and processor architecture are you using (go env)?

ios/arm64

What did you do?

$ CC=$HOME/bin/clangwrap PATH=$PATH:$HOME/bin ./all.bash

What did you expect to see?

No errors.

What did you see instead?

# runtime/race.test
/var/root/goroot/pkg/tool/ios_arm64/link: running /var/root/bin/clangwrap failed: exit status 1
ld: building for iOS, but linking in object file built for macOS, file '/tmp/go-link-1066573738/000000.o' for architecture arm64
Not signing file
clang-5.0: error: linker command failed with exit code 1 (use -v to see invocation)

FAIL	runtime/race [build failed]

I'm guessing the problem is that the race runtime .syso files are hard-coded to macOS.

CC @cherrymui.

[cherrymui]

Yeah, the race detector is not implemented for iOS, only for macOS. Maybe we should skip that test.

[gopherbot]

Change https://golang.org/cl/331050 mentions this issue: runtime/race: use race build tag on syso_test.go

[eliasnaur]

The test fails at build which is unfortunate. Perhaps the linker should skip .syso files whose LC_VERSION_MIN_*/LC_BUILD_VERSION load commands don't match GOOS?

[gopherbot]

Change https://golang.org/cl/372218 mentions this issue: [release-branch.go1.16] runtime/race: use race build tag on syso_test.go

[cherrymui]

@gopherbot please backport this to Go 1.16. This fixes a test currently failing on 1.16 branch.

[gopherbot]

Backport issue(s) opened: #50194 (for 1.16).

Remember to create the cherry-pick CL(s) as soon as the patch is submitted to master, according to https://golang.org/wiki/MinorReleases.