Swift 5.4 on macOS-latest doesn't compile

[adam-fowler]

Describe the bug If you install Swift5.4 on macos-latest you get the following errors when compiling (regardless of what you are compiling)

/Users/runner/work/soto-core/soto-core: error: manifest parse error(s):
/Applications/Xcode_13.2.1.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX12.1.sdk/System/Library/Frameworks/Combine.framework/Modules/Combine.swiftmodule/x86_64-apple-macos.swiftinterface:2599:50: error: no type named 'Sendable' in module 'Swift'
extension Combine.Subscribers.Completion : Swift.Sendable {}
                                                 ^
/Applications/Xcode_13.2.1.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX12.1.sdk/System/Library/Frameworks/Combine.framework/Modules/Combine.swiftmodule/x86_64-apple-macos.swiftinterface:2601:46: error: no type named 'Sendable' in module 'Swift'
extension Combine.Subscribers.Demand : Swift.Sendable {}
                                             ^
/Applications/Xcode_13.2.1.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX12.1.sdk/System/Library/Frameworks/Combine.framework/Modules/Combine.swiftmodule/x86_64-apple-macos.swiftinterface:1:1: error: failed to build module 'Combine' from its module interface; the compiler that produced it, 'Apple Swift version 5.5.2 (swiftlang-1300.0.46.202 clang-1300.0.29.30)', may have used features that aren't supported by this compiler, 'Apple Swift version 5.4.3 (swift-5.4.3-RELEASE)'
// swift-interface-format-version: 1.0
^
/Applications/Xcode_13.2.1.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX12.1.sdk/System/Library/Frameworks/Combine.framework/Modules/Combine.swiftmodule/x86_64-apple-macos.swiftinterface:2599:50: error: no type named 'Sendable' in module 'Swift'
extension Combine.Subscribers.Completion : Swift.Sendable {}
                                                 ^
/Applications/Xcode_13.2.1.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX12.1.sdk/System/Library/Frameworks/Combine.framework/Modules/Combine.swiftmodule/x86_64-apple-macos.swiftinterface:2601:46: error: no type named 'Sendable' in module 'Swift'
extension Combine.Subscribers.Demand : Swift.Sendable {}
                                             ^
/Applications/Xcode_13.2.1.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX12.1.sdk/System/Library/Frameworks/Combine.framework/Modules/Combine.swiftmodule/x86_64-apple-macos.swiftinterface:2599:50: error: no type named 'Sendable' in module 'Swift'
extension Combine.Subscribers.Completion : Swift.Sendable {}
                                                 ^
/Applications/Xcode_13.2.1.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX12.1.sdk/System/Library/Frameworks/Combine.framework/Modules/Combine.swiftmodule/x86_64-apple-macos.swiftinterface:2601:46: error: no type named 'Sendable' in module 'Swift'
extension Combine.Subscribers.Demand : Swift.Sendable {}
                                             ^
/Applications/Xcode_13.2.1.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX12.1.sdk/System/Library/Frameworks/Combine.framework/Modules/Combine.swiftmodule/x86_64-apple-macos.swiftinterface:1:1: error: failed to build module 'Combine' from its module interface; the compiler that produced it, 'Apple Swift version 5.5.2 (swiftlang-1300.0.46.202 clang-1300.0.29.30)', may have used features that aren't supported by this compiler, 'Apple Swift version 5.4.3 (swift-5.4.3-RELEASE)'
// swift-interface-format-version: 1.0
^
/Applications/Xcode_13.2.1.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX12.1.sdk/System/Library/Frameworks/Combine.framework/Modules/Combine.swiftmodule/x86_64-apple-macos.swiftinterface:2599:50: error: no type named 'Sendable' in module 'Swift'
extension Combine.Subscribers.Completion : Swift.Sendable {}
                                                 ^
/Applications/Xcode_13.2.1.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX12.1.sdk/System/Library/Frameworks/Combine.framework/Modules/Combine.swiftmodule/x86_64-apple-macos.swiftinterface:2601:46: error: no type named 'Sendable' in module 'Swift'
extension Combine.Subscribers.Demand : Swift.Sendable {}
                                             ^
/Applications/Xcode_13.2.1.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX12.1.sdk/System/Library/Frameworks/Combine.framework/Modules/Combine.swiftmodule/x86_64-apple-macos.swiftinterface:1:1: error: failed to build module 'Combine' from its module interface; the compiler that produced it, 'Apple Swift version 5.5.2 (swiftlang-1300.0.46.202 clang-1300.0.29.30)', may have used features that aren't supported by this compiler, 'Apple Swift version 5.4.3 (swift-5.4.3-RELEASE)'
// swift-interface-format-version: 1.0
^
/Users/runner/work/soto-core/soto-core/Package.swift:16:8: error: failed to build module 'PackageDescription' from its module interface; it may have been damaged or it may have triggered a bug in the Swift compiler when it was produced
import PackageDescription
       ^
Error: Process completed with exit code 1.

Workflow configuration (please complete the following information):

• Platform: macOS-latest
• Swift version: 5.4

[sammous]

I am having the same issue with swift version 5.3. No sure why #337 was closed as it seems to be still an ongoing problem. To have in mind that the official version points to this so it would be wise to update the doc ( swift 5.3 and 5.4 not supported)