rules_swift is failing with Bazel@HEAD in CI

[sgowroji]

https://buildkite.com/bazel/bazel-at-head-plus-downstream/builds/3256#018a202d-c126-4377-9286-aa36c305ed76

Main pipeline https://buildkite.com/bazel/rules-swift-swift/builds/4473#018a2090-44ee-4d64-bc5b-7faceb961171

Platform : Linux

Log :

ERROR: /var/lib/buildkite-agent/.cache/bazel/_bazel_buildkite-agent/e0fba04d7d9e5bdfaeacf1eecab3e828/external/build_bazel_rules_swift_local_config/BUILD:9:16: While resolving toolchains for target @build_bazel_rules_swift_local_config//:toolchain: No matching toolchains found for types @bazel_tools//tools/cpp:toolchain_type.
To debug, rerun with --toolchain_resolution_debug='@bazel_tools//tools/cpp:toolchain_type'
If platforms or toolchains are a new concept for you, we'd encourage reading https://bazel.build/concepts/platforms-intro.
(02:17:07) ERROR: Analysis of target '//examples/apple/objc_interop:main' failed; build aborted: Analysis failed

Steps :

git clone -v https://github.com/bazelbuild/rules_swift.git

git reset 5e58cfc00d3fc3fe0beb1ff68b30d5e08c5dc07c --hard
export USE_BAZEL_VERSION=6a19449233d6e51d8a862545726a60a611943068

shell_commands:
      - "echo --- Downloading and extracting Swift $SWIFT_VERSION to $SWIFT_HOME"
      - "mkdir $SWIFT_HOME"
      - "curl https://download.swift.org/swift-${SWIFT_VERSION}-release/ubuntu2004/swift-${SWIFT_VERSION}-RELEASE/swift-${SWIFT_VERSION}-RELEASE-ubuntu20.04.tar.gz | tar xvz --strip-components=1 -C $SWIFT_HOME"
   
 bazel build //examples/...
    

CC Greenteam @SalmaSamy

[keith]

Did you bisect this one? I'm surprised that it only broken on linux w/o any changes on our side

[keith]

broken by bazelbuild/bazel@03b8616

[keith]

it's because of these objc_library targets even though they are marked as incompatible on linux

rules_swift/examples/apple/objc_interop/BUILD

Lines 13 to 18 in 270c989

	objc_library(
	name = "PrintStream",
	srcs = ["OIPrintStream.m"],
	hdrs = ["OIPrintStream.h"],
	target_compatible_with = ["@platforms//os:macos"],
	)

[keith]

likely related: bazelbuild/bazel#16662

[keith]

and maybe bazelbuild/bazel#16099

[keith]

#1094

[sgowroji]

Thanks @keith!