[Parity] error: import of shadowed module '_FoundationICU'

[kcieplak]

Is it reproducible with SwiftPM command-line tools: swift build, swift test, swift package etc?

• Confirmed reproduction steps with SwiftPM CLI. The description text must include reproduction steps with either of command-line SwiftPM commands, swift build, swift test, swift package etc.

Description

https://github.com/swiftlang/swift-corelibs-foundation.git
Linux Ubuntu 20.04

The following package does not build using the 'swifbuild' backend but does with 'native'

swift build `--buildsystem=swiftbuild` fails to build package

error: /workspace/spi-workdir/BF3E0FC8-3A39-4A13-9639-A1CEECD0D88B/swift-corelibs-foundation/.build-swiftbuild/checkouts/swift-foundation-icu/icuSources/include/_foundation_unicode/module.modulemap:1:8 import of shadowed module '_FoundationICU'
info: /workspace/spi-workdir/BF3E0FC8-3A39-4A13-9639-A1CEECD0D88B/swift-corelibs-foundation/.build-swiftbuild/x86_64-unknown-linux-gnu/Intermediates.noindex/GeneratedModuleMaps-linux/_FoundationICU.modulemap:1:8 previous definition is here
info: /workspace/spi-workdir/BF3E0FC8-3A39-4A13-9639-A1CEECD0D88B/swift-corelibs-foundation/Sources/CoreFoundation/CFStringTransform.c:22:10 submodule of top-level module '_FoundationICU' implicitly imported here
info: /workspace/spi-workdir/BF3E0FC8-3A39-4A13-9639-A1CEECD0D88B/swift-corelibs-foundation/Sources/CoreFoundation/include/ForSwiftFoundationOnly.h:501:26: warning: ambiguous expansion of macro 'NULL' [-Wambiguous-macro]
  

Expected behavior

Builds

Actual behavior

Fails to build

Steps to reproduce

git clone https://github.com/swiftlang/swift-corelibs-foundation.git
swift build --build-system=swiftbuild

Swift Package Manager version/commit hash

No response

Swift & OS version (output of swift --version ; uname -a)

No response

[owenv]

This might also be #9188 but it's hard to say without more investigation