Bump minimum Swift version to 5.7 (#134)

* Bump minimum Swift version to 5.7

Motivation:

Now that Swift 5.9 is GM we should update the supported versions and
remove 5.6

Modifications:

* Update `Package.swift`
* Remove guards for swift <5.7
* Add deprecation annotations to `LegacyTracer` API
* Delete the 5.6 docker compose file and make a 5.10 one
* Update docs

Result:

Remove support for Swift 5.6, add 5.10

* remove warnings as errors: cannot do this because we support deprecated type

* formatting

---------

Co-authored-by: Konrad `ktoso` Malawski <[email protected]>

Author: rnro

Package.swift

@@ -1,4 +1,4 @@
-// swift-tools-version:5.6
+// swift-tools-version:5.7
 import PackageDescription
 
 let package = Package(

Sources/Instrumentation/Instrument.swift

@@ -15,11 +15,7 @@
 import ServiceContextModule
 
 /// Typealias used to simplify Support of old Swift versions which do not have `Sendable` defined.
-#if swift(>=5.6.0)
 @preconcurrency public protocol _SwiftInstrumentationSendable: Sendable {}
-#else
-public protocol _SwiftInstrumentationSendable {}
-#endif
 
 /// Conforming types are used to extract values from a specific `Carrier`.
 public protocol Extractor: _SwiftInstrumentationSendable {

Sources/Tracing/Docs.docc/Guides/ImplementATracer.md

@@ -125,7 +125,6 @@ The primary goal and user-facing API of a ``Tracer`` is to create spans.
 While you will need to implement all methods of the tracer protocol, the most important one is `startSpan`:
 
 ```swift
-#if swift(>=5.7.0)
 extension MyTracer: Tracer {
     func startSpan<Instant: TracerInstant>(
         _ operationName: String,
@@ -147,7 +146,6 @@ extension MyTracer: Tracer {
         return span
     }
 }
-#endif
 ```
 
 If you can require Swift 5.7 prefer doing so, and return the concrete ``Span`` type from the `startSpan` method. 
@@ -170,4 +168,4 @@ public struct MySpan: Tracing.Span {
 It is possible to implement a span as a struct or a class, but a ``Span`` **must exhibit reference type behavior**.
 In other words, adding an attribute to one reference of a span must be visible in other references to it. 
 
-The ability to implement a span using a struct comes in handy when implementing a "Noop" (do nothing) span and avoids heap allocations. Normal spans though generally will be backed by `class` based storage and should flush themselfes to the owning tracer once the span has been ended
+The ability to implement a span using a struct comes in handy when implementing a "Noop" (do nothing) span and avoids heap allocations. Normal spans though generally will be backed by `class` based storage and should flush themselves to the owning tracer once the span has been ended

Sources/Tracing/Docs.docc/Guides/InstrumentYourLibrary.md

@@ -211,7 +211,7 @@ While this code is very simple for illustration purposes, and it may seem surpri
 
 The above steps are enough if you wanted to provide context propagation. It already enables techniques such as **correlation ids** which can be set once, in one system, and then carried through to any downstream services the code makes calls from while the context is set.
 
-Many libraries also have the opportunity to start trace spans themselfes, on behalf of users, in pieces of the library that can provide useful insight in the behavior or the library in production. For example, the `HTTPServer` can start spans as soon as it begins handling HTTP requests, and this way provide a parent span to any spans the user-code would be creating itself. 
+Many libraries also have the opportunity to start trace spans themselves, on behalf of users, in pieces of the library that can provide useful insight in the behavior or the library in production. For example, the `HTTPServer` can start spans as soon as it begins handling HTTP requests, and this way provide a parent span to any spans the user-code would be creating itself. 
 
 Let us revisit the previous sample `HTTPServer` which restored context around invoking the user-code, and further extend it to start a span including basic information about the `HTTPRequest` being handled:
 

Sources/Tracing/InstrumentationSystem+Tracing.swift

@@ -16,7 +16,6 @@
 
 @available(macOS 10.15, iOS 13, tvOS 13, watchOS 6, *)
 extension InstrumentationSystem {
-    #if swift(>=5.7.0)
     /// Returns the ``Tracer`` bootstrapped as part of the `InstrumentationSystem`.
     ///
     /// If the system was bootstrapped with a `MultiplexInstrument` this function attempts to locate the _first_
@@ -28,14 +27,14 @@ extension InstrumentationSystem {
             (self._findInstrument(where: { $0 is (any Tracer) }) as? (any Tracer))
         return found ?? NoOpTracer()
     }
-    #endif
 
     /// Returns the ``Tracer`` bootstrapped as part of the `InstrumentationSystem`.
     ///
     /// If the system was bootstrapped with a `MultiplexInstrument` this function attempts to locate the _first_
     /// tracing instrument as passed to the multiplex instrument. If none is found, a ``NoOpTracer`` is returned.
     ///
     /// - Returns: A ``Tracer`` if the system was bootstrapped with one, and ``NoOpTracer`` otherwise.
+    @available(*, deprecated, message: "prefer tracer")
     public static var legacyTracer: any LegacyTracer {
         let found: (any LegacyTracer)? =
             (self._findInstrument(where: { $0 is (any LegacyTracer) }) as? (any LegacyTracer))

Sources/Tracing/NoOpTracer.swift

@@ -91,7 +91,6 @@ public struct NoOpTracer: LegacyTracer {
     }
 }
 
-#if swift(>=5.7.0)
 @available(macOS 10.15, iOS 13, tvOS 13, watchOS 6, *)
 extension NoOpTracer: Tracer {
     public func startSpan<Instant: TracerInstant>(
@@ -106,4 +105,3 @@ extension NoOpTracer: Tracer {
         NoOpSpan(context: context())
     }
 }
-#endif

Sources/Tracing/SpanProtocol.swift

@@ -629,7 +629,6 @@ extension SpanAttributes {
     }
 }
 
-#if swift(>=5.2)
 extension SpanAttributes {
     /// Enables for type-safe fluent accessors for attributes.
     public subscript<T>(dynamicMember dynamicMember: KeyPath<SpanAttribute, SpanAttributeKey<T>>) -> SpanAttribute? {
@@ -650,7 +649,6 @@ extension SpanAttributes {
         SpanAttribute._namespace[keyPath: dynamicMember]
     }
 }
-#endif
 
 extension SpanAttributes: ExpressibleByDictionaryLiteral {
     public init(dictionaryLiteral elements: (String, SpanAttribute)...) {

Sources/Tracing/Tracer.swift

@@ -108,7 +108,6 @@ public func startSpan(
     )
 }
 
-#if swift(>=5.7.0)
 /// Start a new ``Span`` using the global bootstrapped tracer reimplementation.
 ///
 /// The current task-local `ServiceContext` is picked up and provided to the underlying tracer.
@@ -155,7 +154,6 @@ public func startSpan(
         line: line
     )
 }
-#endif
 
 // ==== withSpan + sync ---------------------------------------------------
 
@@ -251,8 +249,6 @@ public func withSpan<T>(
     }
 }
 
-#if swift(>=5.7.0)
-
 /// Start a new ``Span`` and automatically end when the `operation` completes,
 /// including recording the `error` in case the operation throws.
 ///
@@ -299,7 +295,6 @@ public func withSpan<T>(
         try operation(anySpan)
     }
 }
-#endif
 
 // ==== withSpan + async --------------------------------------------------
 
@@ -395,7 +390,6 @@ public func withSpan<T>(
     }
 }
 
-#if swift(>=5.7.0)
 /// Start a new ``Span`` and automatically end when the `operation` completes,
 /// including recording the `error` in case the operation throws.
 ///
@@ -442,4 +436,3 @@ public func withSpan<T>(
         try await operation(anySpan)
     }
 }
-#endif

Sources/Tracing/TracerProtocol+Legacy.swift

@@ -25,6 +25,7 @@ import Dispatch
 /// rather than these `startAnySpan` APIs which unconditionally always return existential Spans even when not necessary
 /// (under Swift 5.7+ type-system enhancement wrt. protocols with associated types)..
 @available(macOS 10.15, iOS 13, tvOS 13, watchOS 6, *) // for TaskLocal ServiceContext
+@available(*, deprecated, renamed: "Tracer")
 public protocol LegacyTracer: Instrument {
     /// Start a new span returning an existential ``Span`` reference.
     ///
@@ -54,6 +55,8 @@ public protocol LegacyTracer: Instrument {
     ///   - function: The function name in which the span was started
     ///   - fileID: The `fileID` where the span was started.
     ///   - line: The file line where the span was started.
+
+    @available(*, deprecated, message: "prefer withSpan")
     func startAnySpan<Instant: TracerInstant>(
         _ operationName: String,
         context: @autoclosure () -> ServiceContext,
@@ -70,6 +73,7 @@ public protocol LegacyTracer: Instrument {
     /// such as when using some FaaS providers that may suspend the process after an invocation, but before the backend exports the completed spans.
     ///
     /// This function should not block indefinitely, implementations should offer a configurable timeout for flush operations.
+    @available(*, deprecated)
     func forceFlush()
 }
 
@@ -108,6 +112,7 @@ extension LegacyTracer {
     ///   - function: The function name in which the span was started
     ///   - fileID: The `fileID` where the span was started.
     ///   - line: The file line where the span was started.
+    @available(*, deprecated, message: "prefer withSpan")
     public func startAnySpan<Instant: TracerInstant>(
         _ operationName: String,
         at instant: @autoclosure () -> Instant,

Sources/Tracing/TracerProtocol.swift

@@ -18,8 +18,6 @@
 // ==== -----------------------------------------------------------------------
 // MARK: Tracer protocol
 
-#if swift(>=5.7.0)
-
 /// A tracer capable of creating new trace spans.
 ///
 /// A tracer is a special kind of instrument with the added ability to start a ``Span``.
@@ -325,5 +323,3 @@ extension Tracer {
         }
     }
 }
-
-#endif // Swift 5.7