Retrieve single arch cpu from cc_toolchain instead of from apple_fragment

[thii]

apple_fragment.single_arch_cpu was returning the default macos cpu for
the host platform for tools while it should return the cpu of the
execution platform.

[brentleyjones]

Do you feel this is a bug with apple_fragment.single_arch_cpu?

[thii]

It could be, but I think it's safe to use this as it's the one cc_library and objc_library use.

[keith]

I think now that this might be fixed by the change like this bazelbuild/rules_apple#1154 we should try that first

[brentleyjones]

Now that bazelbuild/rules_apple#1154 is merged, is this still an issue?

[thii]

Yes, still. I think this is a Bazel issue, since rules_swift doesn't depend on rules_apple.

[brentleyjones]

Yep, we have to use this patch as well until Bazel fixes it's stuff. Doesn't look like anyone is looking at it over there so low chance of a 5.0 fix?

[keith]

Can you test this with bazel HEAD in general? A quick look at the bazel source makes it look like the defaults read from https://github.com/bazelbuild/bazel/blob/c873525af9e045c87dfca2ac82ca68e9b76f8820/src/main/java/com/google/devtools/build/lib/rules/apple/AppleConfiguration.java#L82 and https://github.com/bazelbuild/bazel/blob/c873525af9e045c87dfca2ac82ca68e9b76f8820/src/main/java/com/google/devtools/build/lib/rules/apple/AppleCommandLineOptions.java#L201-L203

[thii]

Looks like it has been fixed as of bazelbuild/bazel@c873525.

Do you have any idea which commit fixes this? I think it should be cherry-picked into 5.0.

Edit: See other comments below.

[thii]

Interesting that the baseline of 5.0 doesn't have this issue, but 5.0.0rc2 does.

[thii]

Sorry, above two comments were incorrect. I was testing it wrong due to a bug in bazelisk - it is pulling x86_64 binaries for unreleased commit on M1 bazelbuild/bazelisk#260

Update: It has not been fixed at HEAD.

[brentleyjones]

I say we merge this, to fix the issue, and revert when Bazel gets a fix.

[thii]

Does no one else have this problem? We're still not able to build with universal tools without this patch.

[brentleyjones]

Yes, we need this patch to build universal tools. My comment still stands, I think we should merge it for now.

[thii]

Thanks 🙏
I'm taking this in for now