Bump requirements to Swift 5.4, migrate to @resultBuilder (#442)

This updates the project to use Swift 5.4 across all platforms. Swift 5.4 is now also the required version, which allows us to use `@resultBuilder` instead of the deprecated version of this attribute from Swift 5.3.

Use `carton` 0.11.0 or later from now on to build with SwiftWasm 5.4.0.

.github/workflows/ci.yml

@@ -11,7 +11,7 @@ jobs:
 
     steps:
       - uses: actions/checkout@v2
-      - uses: swiftwasm/swiftwasm-action@v5.3
+      - uses: swiftwasm/swiftwasm-action@v5.4
         with:
           shell-action: carton bundle --product TokamakDemo
 
@@ -20,20 +20,20 @@ jobs:
 
     steps:
       - uses: actions/checkout@v2
-      - uses: swiftwasm/swiftwasm-action@v5.3
+      - uses: swiftwasm/swiftwasm-action@v5.4
         with:
           shell-action: carton test
 
   core_macos_build:
-    runs-on: macos-11.0
+    runs-on: macos-11
 
     steps:
       - uses: actions/checkout@v2
       - name: Run the test suite on macOS, build the demo project for iOS
         shell: bash
         run: |
           set -ex
-          sudo xcode-select --switch /Applications/Xcode_12.4.app/Contents/Developer/
+          sudo xcode-select --switch /Applications/Xcode_12.5.app/Contents/Developer/
           # avoid building unrelated products for testing by specifying the test product explicitly
           swift build --product TokamakPackageTests
           `xcrun --find xctest` .build/debug/TokamakPackageTests.xctest ||
@@ -64,15 +64,15 @@ jobs:
           path: RenderingTests
 
   gtk_macos_build:
-    runs-on: macos-latest
+    runs-on: macos-11
 
     steps:
       - uses: actions/checkout@v2
       - name: Build the GTK renderer on macOS
         shell: bash
         run: |
           set -ex
-          sudo xcode-select --switch /Applications/Xcode_12.4.app/Contents/Developer/
+          sudo xcode-select --switch /Applications/Xcode_12.5.app/Contents/Developer/
 
           brew install gtk+3
 

.github/workflows/codecov.yml

@@ -9,7 +9,7 @@ on:
 jobs:
   codecov:
     container:
-      image: swift:5.3.2-bionic
+      image: swift:5.4-bionic
     runs-on: ubuntu-latest
     steps:
     - run: apt-get update && apt-get install -y gtk+-3.0 libgtk+-3.0

.github/workflows/swiftlint.yml

@@ -18,7 +18,7 @@ jobs:
           git fetch --prune --no-tags --depth=1 origin +refs/heads/${{ github.base_ref }}:refs/heads/${{ github.base_ref }}
       # Diff pull request to current files, then SwiftLint changed files
       - name: GitHub Action for SwiftLint
-        uses: ezraberch/action-swiftlint@3.2.3
+        uses: mayk-it/action-swiftlint@3.2.2
         env:
           DIFF_BASE: ${{ github.base_ref }}
           DIFF_HEAD: HEAD

.swiftformat

@@ -9,4 +9,4 @@
 --wraparguments before-first
 --funcattributes prev-line
 --disable andOperator
---swiftversion 5.3
+--swiftversion 5.4

Package.swift

@@ -1,4 +1,4 @@
-// swift-tools-version:5.3
+// swift-tools-version:5.4
 // The swift-tools-version declares the minimum version of Swift required to
 // build this package.
 
@@ -125,7 +125,7 @@ let package = Package(
         ),
       ]
     ),
-    .target(
+    .executableTarget(
       name: "TokamakGTKDemo",
       dependencies: ["TokamakGTK"],
       resources: [.copy("logo-header.png")]
@@ -136,14 +136,14 @@ let package = Package(
         "TokamakCore",
       ]
     ),
-    .target(
+    .executableTarget(
       name: "TokamakCoreBenchmark",
       dependencies: [
         "Benchmark",
         "TokamakCore",
       ]
     ),
-    .target(
+    .executableTarget(
       name: "TokamakStaticHTMLBenchmark",
       dependencies: [
         "Benchmark",
@@ -167,7 +167,7 @@ let package = Package(
         "OpenCombineJS",
       ]
     ),
-    .target(
+    .executableTarget(
       name: "TokamakDemo",
       dependencies: [
         "TokamakShim",
@@ -185,7 +185,7 @@ let package = Package(
         ),
       ]
     ),
-    .target(
+    .executableTarget(
       name: "TokamakStaticHTMLDemo",
       dependencies: [
         "TokamakStaticHTML",

README.md

@@ -113,9 +113,8 @@ app.
 
 ## Requirements for app developers
 
-- macOS 10.15 and Xcode 11.4 or later. macOS 11.0 and Xcode 12.0 or later are required if you're
-  building a multi-platform app with Tokamak that also needs to support SwiftUI on macOS.
-- [Swift 5.2 or later](https://swift.org/download/) and Ubuntu 18.04 if you'd like to use Linux.
+- macOS 11 and Xcode 12.5. Xcode 13 is currently not supported.
+- [Swift 5.4 or later](https://swift.org/download/) and Ubuntu 18.04 if you'd like to use Linux.
   Other Linux distributions are currently not supported.
 
 ## Requirements for app users
@@ -142,7 +141,7 @@ app by following these steps:
 brew install swiftwasm/tap/carton
 ```
 
-If you had `carton` installed before this, make sure you have version 0.9.0 or greater:
+If you had `carton` installed before this, make sure you have version 0.11.0 or greater:
 
 ```
 carton --version

Sources/TokamakCore/App/Scenes/SceneBuilder.swift

@@ -15,7 +15,7 @@
 //  Created by Carson Katri on 7/16/20.
 //
 
-@_functionBuilder
+@resultBuilder
 public enum SceneBuilder {
   public static func buildBlock<Content: Scene>(_ content: Content) -> some Scene {
     content

Sources/TokamakCore/Views/Navigation/ToolbarContentBuilder.swift

@@ -15,7 +15,8 @@
 //  Created by Carson Katri on 7/7/20.
 //
 
-@_functionBuilder public enum ToolbarContentBuilder<ID> {
+@resultBuilder
+public enum ToolbarContentBuilder<ID> {
   public static func buildBlock<V>(_ content: ToolbarItem<ID, V>)
     -> ToolbarItemGroup<ID, ToolbarItem<ID, V>> where V: View
   {

Sources/TokamakCore/Views/ViewBuilder.swift

@@ -67,7 +67,8 @@ extension Optional: AnyOptional {
   }
 }
 
-@_functionBuilder public enum ViewBuilder {
+@resultBuilder
+public enum ViewBuilder {
   public static func buildBlock() -> EmptyView { EmptyView() }
 
   public static func buildBlock<Content>(