Update supported Swift/Xcode Versions.

.github/workflows/build.yml

@@ -29,25 +29,11 @@ jobs:
         - 5.8.1-jammy
         - 5.7.3-jammy
         - 5.6.3-focal
-        - 5.5.3-focal
-        - 5.4.3-focal
         # protobuf_git can reference a commit, tag, or branch
         # commit: "commits/6935eae45c99926a000ecbef0be20dfd3d159e71"
         # tag: "ref/tags/v3.11.4"
         # branch: "ref/heads/main"
         protobuf_git: ["ref/heads/main"]
-        # We are not testing the SPM plugins on Swift version that don't support SPM plugins
-        include:
-          - swift: 5.8.1-jammy
-            test_spm_plugin: true
-          - swift: 5.7.3-jammy
-            test_spm_plugin: true
-          - swift: 5.6.3-focal
-            test_spm_plugin: true
-          - swift: 5.5.3-focal
-            test_spm_plugin: false
-          - swift: 5.4.3-focal
-            test_spm_plugin: false
     container:
       image: swift:${{ matrix.swift }}
     steps:
@@ -114,7 +100,6 @@ jobs:
       working-directory: main
       run: make test-conformance CONFORMANCE_TEST_RUNNER=../protobuf/cmake_build/conformance_test_runner
     - name: Test SPM plugin
-      if: ${{ matrix.test_spm_plugin }}
       working-directory: main
       run: make test-spm-plugin PROTOC=../protobuf/cmake_build/protoc
 

Documentation/INTERNALS.md

@@ -17,27 +17,13 @@ behavior are always appreciated.
 
 ## Swift Language Support
 
-We guarantee support for Swift versions that are up to one year old.
-For example, in March 2022 (when Swift 5.6 was released), we still
-guaranteed support for Swift 5.3.3 (released in January 2021, and still
-current in March 2021).
-Support for Swift versions older than one year is at the discretion
-of the SwiftProtobuf developers and will depend on the amount of
-effort required to maintain such support.
-We do not as a rule expect to support Swift versions more than two years
-old in any case.
-
-(Originally, we tried to gaurantee "one full major version", which
-was essentially the same as "one year" until Swift 5, at which point
-we discovered that managing CI for 4-year-old releases was rather
-problematic.)
-
-Having said that, the issue is complicated by the fact that there are _toolchain
-versions_ and _language versions_.  As of Swift toolchain 5.x, the 4.2 _language
-version_ is still supported. In that case of SwiftProtobuf, there's the question
-of what _language version_ the core library supports, but also what _language
-versions_ the generated code need to compile (since that code ends up in
-whatever target developers pick).
+SwiftProtobuf tries to support back to the oldest of:
+
+*  The
+   [Swift NIO guidelines support version](https://github.com/apple/swift-nio#supported-versions).
+*  Apple’s App Store submission requirements. This is announced on the
+   [Apple Developer News](https://developer.apple.com/news/) page; an
+   [example from March 2023](https://developer.apple.com/news/?id=jd9wcyov).
 
 When the minimum Swift version gets updated, update:
 - The `README.md` in the root of the project
@@ -48,6 +34,16 @@ When the minimum Swift version gets updated, update:
   versions supported. Eventually the version specific `Package@*.swift`
   files will go away.
 
+  NOTE: As the minimum Xcode version updates, that also implicitly updates
+  the minimum supports Apple OS versions. Those updates also go into the
+  podspec file. If the an older Xcode might support the NIO Swift version,
+  we still listed the lower Swift version but higher Xcode version in the
+  `README.md` and we adopt the deployment minimums from the Xcode in
+  `SwiftProtobuf.podspec`.
+
+  The deployment minimums for Xcode versions can be found on the [Developer
+  Support: Xcode](https://developer.apple.com/support/xcode/) page.
+
 ## Field Storage
 
 The generated message structs follow one of several different patterns

Documentation/PLUGIN.md

@@ -19,9 +19,8 @@ Swift runtime library to your project.
 
 To use Swift with Protocol buffers, you'll need:
 
-* A recent Swift 4.0 compiler that includes the Swift Package Manager.
-  We recommend using the latest release build from
-  [Swift.org](https://swift.org) or the command-line tools included
+* A recent Swift compiler. We recommend using the latest release build
+  from [Swift.org](https://swift.org) or the command-line tools included
   with the latest version of Xcode.
 
 * Google's protoc compiler.  You can get recent versions from
@@ -41,10 +40,6 @@ This will create a binary called `protoc-gen-swift` in the
 `.build/release` directory.  To install, just copy this one executable
 anywhere in your PATH.
 
-NOTE: The Swift runtime support is now included with macOS. If you are
-using old Xcode versions or are on older system versions, you might need
-to use also use `--static-swift-stdlib` with `swift build`.
-
 ### Converting .proto files into Swift
 
 To generate Swift output for your .proto files, you run the `protoc`
@@ -165,8 +160,8 @@ The `proto_file_path` values here should match the paths used in the proto file
 ##### Generation Option: `ImplementationOnlyImports` - `@_implementationOnly`-annotated imports
 
 By default, SwiftProtobuf does not annotate any imports with `@_implementationOnly`.
-However, in some scenarios, such as when distributing an `XCFramework`, imports 
-for types used only internally should be annotated as `@_implementationOnly` to 
+However, in some scenarios, such as when distributing an `XCFramework`, imports
+for types used only internally should be annotated as `@_implementationOnly` to
 avoid exposing internal symbols to clients.
 You can change this with the `ImplementationOnlyImports` option:
 
@@ -178,11 +173,11 @@ The possible values for `ImplementationOnlyImports` are:
 
 * `false` (default): The `@_implementationOnly` annotation will never be used.
 * `true`: Imports of internal dependencies and any modules defined in the module
-mappings will be annotated as `@_implementationOnly`. 
+mappings will be annotated as `@_implementationOnly`.
 
-**Important:** Modules cannot be imported as implementation-only if they're 
+**Important:** Modules cannot be imported as implementation-only if they're
 exposed via public API, so even if `ImplementationOnlyImports` is set to `true`,
-this will only work if the `Visibility` is set to `internal`.  
+this will only work if the `Visibility` is set to `internal`.
 
 
 ### Building your project

README.md

@@ -90,9 +90,9 @@ your project as explained below.
 
 To use Swift with Protocol buffers, you'll need:
 
-* A Swift 5.0 or later compiler (Xcode 10.2 or later).  Support is included for
-  the Swift Package Manager. The Swift protobuf project is being developed and
-  tested against the latest release version of Swift available from
+* A Swift 5.6 or later compiler (or, if building with Xcode, Xcode 14.1 or later
+  as required by the App Store). The Swift protobuf project is being developed
+  and tested against the latest release version of Swift available from
   [Swift.org](https://swift.org)
 
 * Google's protoc compiler.  The Swift protoc plugin is being actively developed

SwiftProtobuf.podspec

@@ -8,10 +8,10 @@ Pod::Spec.new do |s|
   s.source = { :git => 'https://github.com/apple/swift-protobuf.git', :tag => s.version }
 
   s.requires_arc = true
-  s.ios.deployment_target = '9.0'
-  s.osx.deployment_target = '10.11'
-  s.tvos.deployment_target = '9.0'
-  s.watchos.deployment_target = '2.0'
+  s.ios.deployment_target = '11.0'
+  s.osx.deployment_target = '10.13'
+  s.tvos.deployment_target = '11.0'
+  s.watchos.deployment_target = '4.0'
 
   s.cocoapods_version = '>= 1.7.0'