CxxShim cannot be imported on Windows

[compnerd]

S:\SourceCache\firebase\SwiftFirebase\Sources\FirebaseCore\FirebaseAuth+Swift.swift:5:8: error: no such module 'CxxShim'
import CxxShim
       ^

This is with the modulemap and headers being present in the SDK directory.

[compnerd]

PS S:\SourceCache\firebase\SwiftFirebase> dir ${env:SDKROOT}\usr\lib\swift\windows\*.h


    Directory: S:\Library\Developer\Platforms\Windows.platform\Developer\SDKs\Windows.sdk\usr\lib\swift\windows


Mode                 LastWriteTime         Length Name
----                 -------------         ------ ----
-a----         1/10/2023   9:39 AM            105 libcxxshim.h
-a----         4/12/2023   2:16 PM            281 libcxxstdlibshim.h


PS S:\SourceCache\firebase\SwiftFirebase> dir ${env:SDKROOT}\usr\lib\swift\windows\*.modulemap


    Directory: S:\Library\Developer\Platforms\Windows.platform\Developer\SDKs\Windows.sdk\usr\lib\swift\windows


Mode                 LastWriteTime         Length Name
----                 -------------         ------ ----
-a----         4/12/2023   2:16 PM            141 libcxxshim.modulemap

[compnerd]

S:\Library\Developer\Toolchains\unknown-Asserts-development.xctoolchain\usr\bin\swift-frontend.exe -frontend -c S:\SourceCache\firebase\SwiftFirebase\Sources\FirebaseCore\FirebaseApp+Swift.swift S:\SourceCache\firebase\SwiftFirebase\Sources\FirebaseCore\FirebaseAuth+Swift.swift S:\SourceCache\firebase\SwiftFirebase\Sources\FirebaseCore\FirebaseAuthResult+Swift.swift S:\SourceCache\firebase\SwiftFirebase\Sources\FirebaseCore\FirebaseConfiguration.swift S:\SourceCache\firebase\SwiftFirebase\Sources\FirebaseCore\FirebaseLogging+Swift.swift -primary-file S:\SourceCache\firebase\SwiftFirebase\Sources\FirebaseCore\FirebaseOptions+Swift.swift S:\SourceCache\firebase\SwiftFirebase\Sources\FirebaseCore\FirebaseUser+Swift.swift S:\SourceCache\firebase\SwiftFirebase\Sources\FirebaseCore\Swift+Extensions.swift -emit-dependencies-path S:\SourceCache\firebase\SwiftFirebase\.build\x86_64-unknown-windows-msvc\debug\FirebaseCore.build\FirebaseOptions+Swift.d -emit-reference-dependencies-path S:\SourceCache\firebase\SwiftFirebase\.build\x86_64-unknown-windows-msvc\debug\FirebaseCore.build\FirebaseOptions+Swift.swiftdeps -target x86_64-unknown-windows-msvc -disable-objc-interop -cxx-interoperability-mode=default -sdk S:\Library\Developer\Platforms\Windows.platform\Developer\SDKs\Windows.sdk -I S:\SourceCache\firebase\SwiftFirebase\.build\x86_64-unknown-windows-msvc\debug -I S:\Library\Developer\Platforms\Windows.platform\Developer\Library\XCTest-development\usr\lib\swift\windows -I S:\Library\Developer\Platforms\Windows.platform\Developer\Library\XCTest-development\usr\lib\swift\windows\x86_64 -color-diagnostics -enable-testing -g -module-cache-path S:\SourceCache\firebase\SwiftFirebase\.build\x86_64-unknown-windows-msvc\debug\ModuleCache -swift-version 5 -Onone -D SWIFT_PACKAGE -D DEBUG -empty-abi-descriptor -resource-dir S:\Library\Developer\Toolchains\unknown-Asserts-development.xctoolchain\usr\lib\swift -enable-anonymous-context-mangled-names -Xcc -fmodule-map-file=S:\SourceCache\firebase\SwiftFirebase\Sources\firebase\include\module.modulemap -Xcc -I -Xcc S:\SourceCache\firebase\SwiftFirebase\Sources\firebase\include -Xcc -DINTERNAL_EXPERIMENTAL -Xcc -D_CRT_SECURE_NO_WARNINGS -Xcc -IS:\SourceCache\firebase\SwiftFirebase\third_party\firebase-development\usr\include -Xcc -D_MT -Xcc -D_DLL -Xcc -Xclang -Xcc --dependent-lib=msvcrt -Xcc -gdwarf -module-name FirebaseCore -package-name swiftfirebase -plugin-path S:\Library\Developer\Toolchains\unknown-Asserts-development.xctoolchain\usr\lib\swift\host\plugins -plugin-path S:\Library\Developer\Toolchains\unknown-Asserts-development.xctoolchain\usr\local\lib\swift\host\plugins -parse-as-library -o S:\SourceCache\firebase\SwiftFirebase\.build\x86_64-unknown-windows-msvc\debug\FirebaseCore.build\FirebaseOptions+Swift.swift.o -index-store-path S:\SourceCache\firebase\SwiftFirebase\.build\x86_64-unknown-windows-msvc\debug\index\store -index-system-modules

Extracting -resource-dir from the command:

-resource-dir S:\Library\Developer\Toolchains\unknown-Asserts-development.xctoolchain\usr\lib\swift