Add support for Swift 5.1 (5.0 impossible due to compiler bug)

.swiftformat

@@ -1,6 +1,6 @@
 # file options
 
---swiftversion 5.2
+--swiftversion 5.0
 --exclude .build
 --exclude UseCases/.build
 --exclude Tests/LinuxMain.swift

Package@swift-5.0.swift

@@ -0,0 +1,27 @@
+// swift-tools-version:5.0
+import PackageDescription
+
+let package = Package(
+    name: "swift-distributed-tracing-baggage",
+    products: [
+        .library(
+            name: "InstrumentationBaggage",
+            targets: [
+                "InstrumentationBaggage",
+            ]
+        ),
+    ],
+    targets: [
+        .target(name: "InstrumentationBaggage"),
+
+        // ==== --------------------------------------------------------------------------------------------------------
+        // MARK: Tests
+
+        .testTarget(
+            name: "InstrumentationBaggageTests",
+            dependencies: [
+                .target(name: "InstrumentationBaggage"),
+            ]
+        ),
+    ]
+)

Package@swift-5.1.swift

@@ -0,0 +1,27 @@
+// swift-tools-version:5.1
+import PackageDescription
+
+let package = Package(
+    name: "swift-distributed-tracing-baggage",
+    products: [
+        .library(
+            name: "InstrumentationBaggage",
+            targets: [
+                "InstrumentationBaggage",
+            ]
+        ),
+    ],
+    targets: [
+        .target(name: "InstrumentationBaggage"),
+
+        // ==== --------------------------------------------------------------------------------------------------------
+        // MARK: Tests
+
+        .testTarget(
+            name: "InstrumentationBaggageTests",
+            dependencies: [
+                .target(name: "InstrumentationBaggage"),
+            ]
+        ),
+    ]
+)

README.md

@@ -1,16 +1,21 @@
 # 🧳 Distributed Tracing: Baggage
 
+[![Swift 5.0](https://img.shields.io/badge/Swift-5.0-ED523F.svg?style=flat)](https://swift.org/download/)
+[![Swift 5.1](https://img.shields.io/badge/Swift-5.1-ED523F.svg?style=flat)](https://swift.org/download/)
 [![Swift 5.2](https://img.shields.io/badge/Swift-5.2-ED523F.svg?style=flat)](https://swift.org/download/)
 [![Swift 5.3](https://img.shields.io/badge/Swift-5.3-ED523F.svg?style=flat)](https://swift.org/download/)
 [![Swift 5.4](https://img.shields.io/badge/Swift-5.4-ED523F.svg?style=flat)](https://swift.org/download/)
 [![Swift 5.5](https://img.shields.io/badge/Swift-5.5-ED523F.svg?style=flat)](https://swift.org/download/)
+[![Swift 5.6](https://img.shields.io/badge/Swift-5.6-ED523F.svg?style=flat)](https://swift.org/download/)
+[![Swift 5.7](https://img.shields.io/badge/Swift-5.6-ED523F.svg?style=flat)](https://swift.org/download/)
 
-> ⚠️ Automatic propagation through task-locals only supported in Swift >= 5.5
+> **Warning**
+> Automatic propagation through task-locals only supported in Swift >= 5.5
 
 `Baggage` is a minimal (zero-dependency) context propagation container, intended to "carry" baggage items
 for purposes of cross-cutting tools to be built on top of it.
 
-It is modeled after the concepts explained in [W3C Baggage](https://w3c.github.io/baggage/) and the 
+It is modeled after the concepts explained in [W3C Baggage](https://w3c.github.io/baggage/) and the
 in the spirit of [Tracing Plane](https://cs.brown.edu/~jcmace/papers/mace18universal.pdf) 's "Baggage Context" type,
 although by itself it does not define a specific serialization format.
 
@@ -20,7 +25,7 @@ deploy various cross-cutting instruments all reusing the same baggage type. More
 
 ## Dependency
 
- In order to depend on this library you can use the Swift Package Manager, and add the following dependency to your `Package.swift`:
+In order to depend on this library you can use the Swift Package Manager, and add the following dependency to your `Package.swift`:
 
 ```swift
 dependencies: [
@@ -33,18 +38,18 @@ dependencies: [
 
 and depend on the module in your target:
 
-```swift 
+```swift
 targets: [
     .target(
         name: "MyAwesomeApp",
         dependencies: [
             .product(
-              name: "InstrumentationBaggage", 
+              name: "InstrumentationBaggage",
               package: "swift-distributed-tracing-baggage"
             ),
         ]
     ),
-    // ... 
+    // ...
 ]
 ```
 

Sources/InstrumentationBaggage/Baggage.swift

@@ -106,7 +106,7 @@ extension Baggage {
     /// not being sure where to obtain a baggage from, or other framework limitations -- e.g. the outer framework not being
     /// baggage aware just yet.
     public static var topLevel: Baggage {
-        Baggage()
+        return Baggage()
     }
 }
 
@@ -150,7 +150,7 @@ extension Baggage {
     private enum TODOKey: BaggageKey {
         typealias Value = TODOLocation
         static var nameOverride: String? {
-            "todo"
+            return "todo"
         }
     }
 }
@@ -207,12 +207,12 @@ extension Baggage {
 extension Baggage {
     /// The number of items in the baggage.
     public var count: Int {
-        self._storage.count
+        return self._storage.count
     }
 
     /// A Boolean value that indicates whether the baggage is empty.
     public var isEmpty: Bool {
-        self._storage.isEmpty
+        return self._storage.isEmpty
     }
 
     /// Iterate through all items in this `Baggage` by invoking the given closure for each item.

Sources/InstrumentationBaggage/BaggageKey.swift

@@ -58,7 +58,7 @@ public protocol BaggageKey: _Baggage_Sendable {
 }
 
 extension BaggageKey {
-    public static var nameOverride: String? { nil }
+    public static var nameOverride: String? { return nil }
 }
 
 /// A type-erased ``BaggageKey`` used when iterating through the ``Baggage`` using its `forEach` method.
@@ -71,7 +71,7 @@ public struct AnyBaggageKey: _Baggage_Sendable {
     /// A human-readable String representation of the underlying key.
     /// If no explicit name has been set on the wrapped key the type name is used.
     public var name: String {
-        self._nameOverride ?? String(describing: self.keyType.self)
+        return self._nameOverride ?? String(describing: self.keyType.self)
     }
 
     init<Key: BaggageKey>(_ keyType: Key.Type) {
@@ -82,7 +82,7 @@ public struct AnyBaggageKey: _Baggage_Sendable {
 
 extension AnyBaggageKey: Hashable {
     public static func == (lhs: AnyBaggageKey, rhs: AnyBaggageKey) -> Bool {
-        ObjectIdentifier(lhs.keyType) == ObjectIdentifier(rhs.keyType)
+        return ObjectIdentifier(lhs.keyType) == ObjectIdentifier(rhs.keyType)
     }
 
     public func hash(into hasher: inout Hasher) {

docker/docker-compose.1804.50.yaml

@@ -0,0 +1,16 @@
+version: "3"
+
+services:
+
+  runtime-setup:
+    image: swift-distributed-tracing-baggage:18.04-5.0
+    build:
+      args:
+        ubuntu_version: "bionic"
+        swift_version: "5.0"
+
+  test:
+    image: swift-distributed-tracing-baggage:18.04-5.0
+
+  shell:
+    image: swift-distributed-tracing-baggage:18.04-5.0

docker/docker-compose.1804.51.yaml

@@ -0,0 +1,16 @@
+version: "3"
+
+services:
+
+  runtime-setup:
+    image: swift-distributed-tracing-baggage:18.04-5.1
+    build:
+      args:
+        ubuntu_version: "bionic"
+        swift_version: "5.1"
+
+  test:
+    image: swift-distributed-tracing-baggage:18.04-5.1
+
+  shell:
+    image: swift-distributed-tracing-baggage:18.04-5.1