API digester fails to construct argument to load C targets

[bkhouri]

❯ /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/swift-api-digester -dump-sdk -abort-on-module-fail -swift-only -avoid-tool-args -target arm64-apple-macos10.13 -F /private/var/folders/9j/994sp90x6y3232rzrl9h_z4w0000gn/T/Miscellaneous_APIDiff.PSIZTD/CTargetDep/.build/out/apidiff/55f3a0a09b545c57e1a61d86a59a25decefbc8f5-checkout/.build/Products/Debug/PackageFrameworks -F /private/var/folders/9j/994sp90x6y3232rzrl9h_z4w0000gn/T/Miscellaneous_APIDiff.PSIZTD/CTargetDep/.build/out/apidiff/55f3a0a09b545c57e1a61d86a59a25decefbc8f5-checkout/.build/Products/Debug -Fsystem /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/Library/Frameworks -Isystem /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/usr/lib -sdk /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX27.0.sdk -module Bar -o /private/var/folders/9j/994sp90x6y3232rzrl9h_z4w0000gn/T/Miscellaneous_APIDiff.PSIZTD/CTargetDep/.build/out/apidiff/55f3a0a09b545c57e1a61d86a59a25decefbc8f5-baselines/Bar/ABI/arm64-macos.json -I /private/var/folders/9j/994sp90x6y3232rzrl9h_z4w0000gn/T/Miscellaneous_APIDiff.PSIZTD/CTargetDep/.build/out/apidiff/55f3a0a09b545c57e1a61d86a59a25decefbc8f5-checkout/.build/Products/Debug      
<unknown>:0: error: missing required module 'Foo'
Failed to load module: Bar

[bkhouri]

The issue is fixed was related to a swift-api-digester executable that did not support the -Xcc arguments. See swiftlang/swift-package-manager#9729.