source compatibility project Deferred fails with a compiler error

[eeckstein]

Description

/build/swift-source-compat-suite/project_cache/Deferred/Sources/Deferred/Executor.swift:129:13: error: 'getCFRunLoop' is inaccessible due to 'internal' protection level
127 |             perform(body)
128 |         } else {
129 |             getCFRunLoop().submit(body)
    |             `- error: 'getCFRunLoop' is inaccessible due to 'internal' protection level
130 |         }
131 |     }

Reproduction

builds:
https://ci.swift.org/job/swift-6.0-source-compat-suite-debug-ubuntu-2004/121/
https://ci.swift.org/job/swift-6.0-source-compat-suite-ubuntu-2004/121/
https://ci.swift.org/job/swift-source-compat-suite-debug-ubuntu-2004/499/
https://ci.swift.org/job/swift-source-compat-suite-ubuntu-2004/599/

log: https://ci.swift.org/job/swift-6.0-source-compat-suite-debug-ubuntu-2004/121/artifact/build/swift-source-compat-suite/FAIL_vapor_routing_4.2_BuildSwiftPackage.log

Expected behavior

should build fine

Environment

CI

Additional information

No response

[kylesluder]

Caused by swift/swift-corelibs-foundation#4927.

[mickeyl]

This is a) a regression, b) bad for existing software that relies on the CFRunLoop API, and c) yet another difference to Apple platforms. I thought the idea was to reduce differences, not to increase them. Please consider reverting this.

[mickeyl]

I'd welcome a comment from the ones in power. Do you leave this regression open or is it planned to repair it? I can't move to Swift 6 on Linux because of that.