Thanks for looking into this! I've pushed a repo of the project that I'm able to repro this in here: GitHub - ciauri/Halp: Sample Project to reproduce Xcode 11 Bug FB7040693 when dealing with Swift Packages and the -Objc flag
Just init the Package dir as a git repo, make a dummy commit, then add it as a swift package dependency to the StaticLib project via the xcode tool and then attempt to build the App target. The static lib target will build fine, it's just the App that seems to have this issue.
Here is the resulting error message:
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Ld /Users/stephen.ciauri/Library/Developer/Xcode/DerivedData/App-czvrzrbbjmoyjdcjoekskyustvxd/Build/Products/Debug-iphonesimulator/App.app/App normal x86_64 (in target 'App' from project 'App')
cd /Users/stephen.ciauri/Downloads/Halp-master/App
/Applications/Xcode-beta.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang -target x86_64-apple-ios13.0-simulator -isysroot /Applications/Xcode-beta.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator13.0.sdk -L/Users/stephen.ciauri/Library/Developer/Xcode/DerivedData/App-czvrzrbbjmoyjdcjoekskyustvxd/Build/Products/Debug-iphonesimulator -F/Users/stephen.ciauri/Library/Developer/Xcode/DerivedData/App-czvrzrbbjmoyjdcjoekskyustvxd/Build/Products/Debug-iphonesimulator -filelist /Users/stephen.ciauri/Library/Developer/Xcode/DerivedData/App-czvrzrbbjmoyjdcjoekskyustvxd/Build/Intermediates.noindex/App.build/Debug-iphonesimulator/App.build/Objects-normal/x86_64/App.LinkFileList -Xlinker -rpath -Xlinker @executable_path/Frameworks -dead_strip -Xlinker -object_path_lto -Xlinker /Users/stephen.ciauri/Library/Developer/Xcode/DerivedData/App-czvrzrbbjmoyjdcjoekskyustvxd/Build/Intermediates.noindex/App.build/Debug-iphonesimulator/App.build/Objects-normal/x86_64/App_lto.o -Xlinker -export_dynamic -Xlinker -no_deduplicate -Xlinker -objc_abi_version -Xlinker 2 -fobjc-link-runtime -L/Applications/Xcode-beta.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/swift/iphonesimulator -L/usr/lib/swift -Xlinker -add_ast_path -Xlinker /Users/stephen.ciauri/Library/Developer/Xcode/DerivedData/App-czvrzrbbjmoyjdcjoekskyustvxd/Build/Intermediates.noindex/App.build/Debug-iphonesimulator/App.build/Objects-normal/x86_64/App.swiftmodule -ObjC -Xlinker -sectcreate -Xlinker __TEXT -Xlinker __entitlements -Xlinker /Users/stephen.ciauri/Library/Developer/Xcode/DerivedData/App-czvrzrbbjmoyjdcjoekskyustvxd/Build/Intermediates.noindex/App.build/Debug-iphonesimulator/App.build/App.app-Simulated.xcent /Users/stephen.ciauri/Library/Developer/Xcode/DerivedData/App-czvrzrbbjmoyjdcjoekskyustvxd/Build/Products/Debug-iphonesimulator/libStaticLib.a -Xlinker -dependency_info -Xlinker /Users/stephen.ciauri/Library/Developer/Xcode/DerivedData/App-czvrzrbbjmoyjdcjoekskyustvxd/Build/Intermediates.noindex/App.build/Debug-iphonesimulator/App.build/Objects-normal/x86_64/App_dependency_info.dat -o /Users/stephen.ciauri/Library/Developer/Xcode/DerivedData/App-czvrzrbbjmoyjdcjoekskyustvxd/Build/Products/Debug-iphonesimulator/App.app/App -Xlinker -add_ast_path -Xlinker /Users/stephen.ciauri/Library/Developer/Xcode/DerivedData/App-czvrzrbbjmoyjdcjoekskyustvxd/Build/Intermediates.noindex/StaticLib.build/Debug-iphonesimulator/StaticLib.build/Objects-normal/x86_64/StaticLib.swiftmodule
duplicate symbol 'Package.Package.init(text: Swift.String) -> Package.Package' in:
/Users/stephen.ciauri/Library/Developer/Xcode/DerivedData/App-czvrzrbbjmoyjdcjoekskyustvxd/Build/Products/Debug-iphonesimulator/libStaticLib.a(Package.o)
duplicate symbol 'default argument 0 of Package.Package.init(text: Swift.String) -> Package.Package' in:
/Users/stephen.ciauri/Library/Developer/Xcode/DerivedData/App-czvrzrbbjmoyjdcjoekskyustvxd/Build/Products/Debug-iphonesimulator/libStaticLib.a(Package.o)
duplicate symbol 'Package.Package.text.modify : Swift.String' in:
/Users/stephen.ciauri/Library/Developer/Xcode/DerivedData/App-czvrzrbbjmoyjdcjoekskyustvxd/Build/Products/Debug-iphonesimulator/libStaticLib.a(Package.o)
duplicate symbol 'Package.Package.text.getter : Swift.String' in:
/Users/stephen.ciauri/Library/Developer/Xcode/DerivedData/App-czvrzrbbjmoyjdcjoekskyustvxd/Build/Products/Debug-iphonesimulator/libStaticLib.a(Package.o)
duplicate symbol 'property descriptor for Package.Package.text : Swift.String' in:
/Users/stephen.ciauri/Library/Developer/Xcode/DerivedData/App-czvrzrbbjmoyjdcjoekskyustvxd/Build/Products/Debug-iphonesimulator/libStaticLib.a(Package.o)
duplicate symbol 'variable initialization expression of Package.Package.text : Swift.String' in:
/Users/stephen.ciauri/Library/Developer/Xcode/DerivedData/App-czvrzrbbjmoyjdcjoekskyustvxd/Build/Products/Debug-iphonesimulator/libStaticLib.a(Package.o)
duplicate symbol 'Package.Package.text.setter : Swift.String' in:
/Users/stephen.ciauri/Library/Developer/Xcode/DerivedData/App-czvrzrbbjmoyjdcjoekskyustvxd/Build/Products/Debug-iphonesimulator/libStaticLib.a(Package.o)
duplicate symbol 'Package.Package.init() -> Package.Package' in:
/Users/stephen.ciauri/Library/Developer/Xcode/DerivedData/App-czvrzrbbjmoyjdcjoekskyustvxd/Build/Products/Debug-iphonesimulator/libStaticLib.a(Package.o)
duplicate symbol 'type metadata accessor for Package.Package' in:
/Users/stephen.ciauri/Library/Developer/Xcode/DerivedData/App-czvrzrbbjmoyjdcjoekskyustvxd/Build/Products/Debug-iphonesimulator/libStaticLib.a(Package.o)
duplicate symbol 'nominal type descriptor for Package.Package' in:
/Users/stephen.ciauri/Library/Developer/Xcode/DerivedData/App-czvrzrbbjmoyjdcjoekskyustvxd/Build/Products/Debug-iphonesimulator/libStaticLib.a(Package.o)
duplicate symbol 'type metadata for Package.Package' in:
/Users/stephen.ciauri/Library/Developer/Xcode/DerivedData/App-czvrzrbbjmoyjdcjoekskyustvxd/Build/Products/Debug-iphonesimulator/libStaticLib.a(Package.o)
ld: 11 duplicate symbols for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)