Drop support for Swift 5.10

.github/workflows/build.yml

@@ -24,14 +24,8 @@ jobs:
         # which is also what would be desired, so we don't bother listing explicit ones.
         swift:
         - version: "6.2"
-          hook: "SWIFT_BUILD_TEST_HOOK=\"-Xswiftc -warnings-as-errors\""
         - version: "6.1"
-          hook: "SWIFT_BUILD_TEST_HOOK=\"-Xswiftc -warnings-as-errors\""
         - version: "6.0"
-          hook: "SWIFT_BUILD_TEST_HOOK=\"-Xswiftc -warnings-as-errors\""
-        - version: "5.10"
-          # No "hook", see https://github.com/apple/swift-protobuf/issues/1560 for the
-          # current issue with using -warnings-as-errors on linux.
     container:
       image: swift:${{ matrix.swift.version }}
     steps:
@@ -47,20 +41,14 @@ jobs:
       # `make` is needed for using our own `Makefile`.
       run: apt-get update && apt-get install -y make g++
     - name: Build
-      run: make build ${{ matrix.swift.hook }}
+      run: make build SWIFT_BUILD_TEST_HOOK="-Xswiftc -warnings-as-errors"
     - name: Test runtime
-      run: make test-runtime ${{ matrix.swift.hook }}
+      run: make test-runtime SWIFT_BUILD_TEST_HOOK="-Xswiftc -warnings-as-errors"
     - name: Test plugin
-      # The protoc build isn't part of Package@swift-5.10.swift
-      if: ${{ matrix.swift.version != '5.10' }}
       run: make test-plugin
     - name: Test SPM plugin
-      # The protoc build isn't part of Package@swift-5.10.swift
-      if: ${{ matrix.swift.version != '5.10' }}
       run: make test-spm-plugin
     - name: Compilation Tests
-      # The protoc build isn't part of Package@swift-5.10.swift
-      if: ${{ matrix.swift.version != '5.10' }}
       run: make compile-tests
 
   api-breakage:

Makefile

@@ -213,14 +213,8 @@ test-plugin: build ${PROTOC_GEN_SWIFT} ${PROTOC}
 	diff -ru _test Reference
 
 # Test the SPM plugin.
-# TODO: simplify this when swift 5.10 support is dropped.
 test-spm-plugin:
-	@SWIFT_VERSION=$$(${SWIFT} --version | head -n1 | sed 's/.*Swift version \([0-9]*\)\..*/\1/'); \
-	if [ "$$SWIFT_VERSION" -lt 6 ]; then \
-		env PROTOC_PATH=$$(realpath ${PROTOC}) ${SWIFT} test --package-path PluginExamples; \
-	else \
-		${SWIFT} test --package-path PluginExamples; \
-	fi
+	${SWIFT} test --package-path PluginExamples
 
 compile-tests: \
 	compile-tests-multimodule \
@@ -233,14 +227,8 @@ compile-tests-multimodule:
 
 # Test that ensures that using access level modifiers on imports yields code that's buildable
 # when `InternalImportsByDefault` is enabled on the module.
-# TODO: simplify this when swift 5.10 support is dropped.
 compile-tests-internalimportsbydefault:
-	@SWIFT_VERSION=$$(${SWIFT} --version | head -n1 | sed 's/.*Swift version \([0-9]*\)\..*/\1/'); \
-	if [ "$$SWIFT_VERSION" -lt 6 ]; then \
-		env PROTOC_PATH=$$(realpath ${PROTOC}) ${SWIFT} build --package-path CompileTests/InternalImportsByDefault; \
-	else \
-		${SWIFT} build --package-path CompileTests/InternalImportsByDefault; \
-	fi
+	${SWIFT} build --package-path CompileTests/InternalImportsByDefault
 
 
 # Rebuild the reference files by running the local version of protoc-gen-swift

Package.swift

@@ -417,7 +417,7 @@ let package = Package(
             swiftSettings: .packageSettings
         ),
     ],
-    swiftLanguageModes: [.v5],
+    swiftLanguageModes: [.v6],
     cxxLanguageStandard: .gnucxx17
 )
 
@@ -426,8 +426,7 @@ let package = Package(
 extension Array where Element == PackageDescription.SwiftSetting {
     static var packageSettings: Self {
         [
-            .enableExperimentalFeature("StrictConcurrency=complete"),
-            .enableUpcomingFeature("ExistentialAny"),
+            .enableUpcomingFeature("ExistentialAny")
         ]
     }
 }

Package@swift-6.0.swift

@@ -1,4 +1,4 @@
-// swift-tools-version:5.10
+// swift-tools-version:6.0
 
 // Package.swift
 //
@@ -408,7 +408,7 @@ let package = Package(
             swiftSettings: .packageSettings
         ),
     ],
-    swiftLanguageVersions: [.v5],
+    swiftLanguageModes: [.v6],
     cxxLanguageStandard: .gnucxx17
 )
 
@@ -417,8 +417,7 @@ let package = Package(
 extension Array where Element == PackageDescription.SwiftSetting {
     static var packageSettings: Self {
         [
-            .enableExperimentalFeature("StrictConcurrency=complete"),
-            .enableUpcomingFeature("ExistentialAny"),
+            .enableUpcomingFeature("ExistentialAny")
         ]
     }
 }

Plugins/SwiftProtobufPlugin/plugin.swift

@@ -6,7 +6,7 @@ struct SwiftProtobufPlugin {
     /// Errors thrown by the `SwiftProtobufPlugin`
     enum PluginError: Error, CustomStringConvertible {
         /// Indicates that the target where the plugin was applied to was not `SourceModuleTarget`.
-        case invalidTarget(Target)
+        case invalidTarget(String)
         /// Indicates that the file extension of an input file was not `.proto`.
         case invalidInputFileExtension(String)
         /// Indicates that there was no configuration file at the required location.
@@ -15,7 +15,7 @@ struct SwiftProtobufPlugin {
         var description: String {
             switch self {
             case let .invalidTarget(target):
-                return "Expected a SwiftSourceModuleTarget but got '\(type(of: target))'."
+                return "Expected a SwiftSourceModuleTarget but got '\(target)'."
             case let .invalidInputFileExtension(path):
                 return "The input file '\(path)' does not have a '.proto' extension."
             case let .noConfigFound(path):
@@ -245,7 +245,7 @@ extension SwiftProtobufPlugin: BuildToolPlugin {
         target: Target
     ) async throws -> [Command] {
         guard let swiftTarget = target as? SwiftSourceModuleTarget else {
-            throw PluginError.invalidTarget(target)
+            throw PluginError.invalidTarget(String(describing: type(of: target)))
         }
         return try createBuildCommands(
             pluginWorkDirectory: context.pluginWorkDirectory,