@dynamicMemberLookup
public struct Object {

    public subscript(dynamicMember keyPath: KeyPath<Object, Int>) -> String {
        String(self[keyPath: keyPath])
    }
    
//    subscript(dynamicMember keyPath: KeyPath<Object, Int>) -> Int {
//        self[keyPath: keyPath]
//    }
    
    public let value = 1
}

CompileSwiftSources normal x86_64 com.apple.xcode.tools.swift.compiler (in target 'test' from project 'test')
    cd /tmp/test
    export DEVELOPER_DIR=/Applications/Xcode/Xcode-11.3.0.app/Contents/Developer
    export SDKROOT=/Applications/Xcode/Xcode-11.3.0.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.15.sdk
    /Applications/Xcode/Xcode-11.3.0.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/swiftc -incremental -module-name test -Onone -enable-batch-mode -enforce-exclusivity=checked @/Users/oat01/Library/Developer/Xcode/DerivedData/test-dthhutsfmixdgkfbohwjdhmccvqj/Build/Intermediates.noindex/test.build/Debug/test.build/Objects-normal/x86_64/test.SwiftFileList -DDEBUG -v -sdk /Applications/Xcode/Xcode-11.3.0.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.15.sdk -target x86_64-apple-macos10.15 -g -module-cache-path /Users/oat01/Library/Developer/Xcode/DerivedData/ModuleCache.noindex -Xfrontend -serialize-debugging-options -enable-testing -index-store-path /Users/oat01/Library/Developer/Xcode/DerivedData/test-dthhutsfmixdgkfbohwjdhmccvqj/Index/DataStore -swift-version 5 -I /Users/oat01/Library/Developer/Xcode/DerivedData/test-dthhutsfmixdgkfbohwjdhmccvqj/Build/Products/Debug -F /Users/oat01/Library/Developer/Xcode/DerivedData/test-dthhutsfmixdgkfbohwjdhmccvqj/Build/Products/Debug -c -j8 -output-file-map /Users/oat01/Library/Developer/Xcode/DerivedData/test-dthhutsfmixdgkfbohwjdhmccvqj/Build/Intermediates.noindex/test.build/Debug/test.build/Objects-normal/x86_64/test-OutputFileMap.json -parseable-output -serialize-diagnostics -emit-dependencies -emit-module -emit-module-path /Users/oat01/Library/Developer/Xcode/DerivedData/test-dthhutsfmixdgkfbohwjdhmccvqj/Build/Intermediates.noindex/test.build/Debug/test.build/Objects-normal/x86_64/test.swiftmodule -Xcc -I/Users/oat01/Library/Developer/Xcode/DerivedData/test-dthhutsfmixdgkfbohwjdhmccvqj/Build/Intermediates.noindex/test.build/Debug/test.build/swift-overrides.hmap -Xcc -iquote -Xcc /Users/oat01/Library/Developer/Xcode/DerivedData/test-dthhutsfmixdgkfbohwjdhmccvqj/Build/Intermediates.noindex/test.build/Debug/test.build/test-generated-files.hmap -Xcc -I/Users/oat01/Library/Developer/Xcode/DerivedData/test-dthhutsfmixdgkfbohwjdhmccvqj/Build/Intermediates.noindex/test.build/Debug/test.build/test-own-target-headers.hmap -Xcc -I/Users/oat01/Library/Developer/Xcode/DerivedData/test-dthhutsfmixdgkfbohwjdhmccvqj/Build/Intermediates.noindex/test.build/Debug/test.build/test-all-target-headers.hmap -Xcc -iquote -Xcc /Users/oat01/Library/Developer/Xcode/DerivedData/test-dthhutsfmixdgkfbohwjdhmccvqj/Build/Intermediates.noindex/test.build/Debug/test.build/test-project-headers.hmap -Xcc -I/Users/oat01/Library/Developer/Xcode/DerivedData/test-dthhutsfmixdgkfbohwjdhmccvqj/Build/Products/Debug/include -Xcc -I/Users/oat01/Library/Developer/Xcode/DerivedData/test-dthhutsfmixdgkfbohwjdhmccvqj/Build/Intermediates.noindex/test.build/Debug/test.build/DerivedSources-normal/x86_64 -Xcc -I/Users/oat01/Library/Developer/Xcode/DerivedData/test-dthhutsfmixdgkfbohwjdhmccvqj/Build/Intermediates.noindex/test.build/Debug/test.build/DerivedSources/x86_64 -Xcc -I/Users/oat01/Library/Developer/Xcode/DerivedData/test-dthhutsfmixdgkfbohwjdhmccvqj/Build/Intermediates.noindex/test.build/Debug/test.build/DerivedSources -Xcc -DDEBUG=1 -emit-objc-header -emit-objc-header-path /Users/oat01/Library/Developer/Xcode/DerivedData/test-dthhutsfmixdgkfbohwjdhmccvqj/Build/Intermediates.noindex/test.build/Debug/test.build/Objects-normal/x86_64/test-Swift.h -working-directory /tmp/test

Apple Swift version 5.1.3 (swiftlang-1100.0.282.1 clang-1100.0.33.15)
Target: x86_64-apple-macos10.15
<unknown>:0: error: unable to execute command: Illegal instruction: 4
<unknown>:0: error: compile command failed due to signal 4 (use -v to see invocation)