swift-frontend flag -target-variant does not persist in swift object file when generating static library

[jpeezzy]

Description

Currently, the Cxx-interop module located at swift/stdlib is the only component that compiles as a static library while only containing swift files. When performing standard builds with cxx-interop enabled, the object files that are generated using swift-frontend ( Cxx.o , CxxStdlib.o ) do not contain maccatalyst platform when linking to a static library using lipo

Reproduction

./swift/utils/build-script --skip-build-benchmarks true -R -i --enable-experimental-cxx-interop true --enable-cxx-interop-swift-bridging-header true  --skip-watchos --skip-tvos --skip-ios --enable-experimental-string-processing true --maccatalyst true --build-swift-private-stdlib false

Expected behavior

when running otool -l lib/swift/macosx/arm64/libswiftCxxStdlib.a | grep platform, you should see both platform 1 and platform 6 ( maccatalyst ), but instead you only see platform 1

Environment

swift-5.10-release, but is also in main as well.

Additional information

No response