--ios_multi_cpus defaults to x86_64 on M1 Macs

[brentleyjones]

Description of the problem / feature request:

--ios_multi_cpus should default to sim_arm64 on M1 Macs, but still defaults to x86_64.

Feature requests: what underlying problem are you trying to solve with this feature?

M1 Mac users shouldn't have to override --ios_multi_cpus to get the proper default.

Bugs: what's the simplest, easiest way to reproduce this bug? Please provide a minimal example if possible.

Build an ios_application target on an M1 Mac, see that the architecture is for the x86_64 simulator.

I think that this might be the issue:

bazel/src/main/starlark/builtins_bzl/common/objc/transitions.bzl

Lines 70 to 73 in e50b203

	def _ios_cpu_from_cpu(cpu):
	if cpu.startswith(IOS_CPU_PREFIX):
	return cpu[len(IOS_CPU_PREFIX):]
	return DEFAULT_IOS_CPU

d7628e1 changed the default in one place already.

What operating system are you running Bazel on?

macOS 11.6.1 (arm64)

What's the output of bazel info release?

release 6.0.0-pre.20211101.2

[brentleyjones]

Probably can reopen #13873 instead? Not sure if it's a different issue.

[keith]

That Pr Was merged so probably want a new one instead

[keith]

We think now this is likely related to this transition bazelbuild/rules_apple#1154

[gregestren]

If bazelbuild/rules_apple#1154 fixes this, can we mark as such in the description to close this issue when ready?

[brentleyjones]

Done. When it's merged it will close this.

[keith]

Didn't work because of ACL, but that's merged