Remove Snapshot types from non-Darwin builds. (swiftlang#540)

Now that we've landed and tagged swiftlang#479 in 0.11.0, we no longer need to
keep building the snapshot types for non-Darwin platforms because we
have a stable, permanent replacement for them.

We need to keep them around on Darwin to support Xcode 16 betas.

### Checklist:

- [x] Code and documentation should follow the style of the [Style
Guide](https://github.com/apple/swift-testing/blob/main/Documentation/StyleGuide.md).
- [x] If public symbols are renamed or modified, DocC references should
be updated.

Author: grynspan

Package.swift

@@ -132,6 +132,7 @@ extension Array where Element == PackageDescription.SwiftSetting {
 
       .define("SWT_NO_FILE_IO", .when(platforms: [.wasi])),
       .define("SWT_NO_EXIT_TESTS", .when(platforms: [.iOS, .watchOS, .tvOS, .visionOS, .wasi])),
+      .define("SWT_NO_SNAPSHOT_TYPES", .when(platforms: [.linux, .windows, .wasi])),
     ]
   }
 

Sources/Testing/ABI/EntryPoints/EntryPoint.swift

@@ -512,10 +512,12 @@ public func configurationForEntryPoint(from args: __CommandLineArguments_v0) thr
 /// - Throws: If `version` is not a supported ABI version.
 func eventHandlerForStreamingEvents(version: Int?, forwardingTo eventHandler: @escaping @Sendable (UnsafeRawBufferPointer) -> Void) throws -> Event.Handler {
   switch version {
+#if !SWT_NO_SNAPSHOT_TYPES
   case -1:
     // Legacy support for Xcode 16 betas. Support for this undocumented version
     // will be removed in a future update. Do not use it.
     eventHandlerForStreamingEventSnapshots(to: eventHandler)
+#endif
   case nil, 0:
     ABIv0.Record.eventHandler(forwardingTo: eventHandler)
   case let .some(unsupportedVersion):
@@ -547,7 +549,7 @@ private func _writeJSONLine(_ json: UnsafeRawBufferPointer, to file: borrowing F
   if _slowPath(json.contains(where: isASCIINewline)) {
 #if DEBUG
     let message = Event.ConsoleOutputRecorder.warning(
-      "JSON encoder produced one or more newline characters while encoding an event snapshot. Please file a bug report at https://github.com/apple/swift-testing/issues/new",
+      "JSON encoder produced one or more newline characters while encoding an event to JSON. Please file a bug report at https://github.com/apple/swift-testing/issues/new",
       options: .for(.stderr)
     )
 #if SWT_TARGET_OS_APPLE

Sources/Testing/ABI/v0/ABIv0.Record+Streaming.swift

@@ -45,6 +45,7 @@ extension ABIv0.Record {
   }
 }
 
+#if !SWT_NO_SNAPSHOT_TYPES
 // MARK: - Experimental event streaming
 
 /// A type containing an event snapshot and snapshots of the contents of an
@@ -107,3 +108,4 @@ func eventHandlerForStreamingEventSnapshots(
   }
 }
 #endif
+#endif

Sources/Testing/Events/Event.swift

@@ -287,6 +287,7 @@ extension Event {
   }
 }
 
+#if !SWT_NO_SNAPSHOT_TYPES
 // MARK: - Snapshotting
 
 extension Event {
@@ -509,3 +510,4 @@ extension Event.Context {
     }
   }
 }
+#endif

Sources/Testing/Expectations/Expectation.swift

@@ -53,6 +53,7 @@ public struct ExpectationFailedError: Error {
   public var expectation: Expectation
 }
 
+#if !SWT_NO_SNAPSHOT_TYPES
 // MARK: - Snapshotting
 
 extension Expectation {
@@ -100,3 +101,4 @@ extension Expectation {
     }
   }
 }
+#endif

Sources/Testing/Issues/ErrorSnapshot.swift

@@ -8,6 +8,7 @@
 // See https://swift.org/CONTRIBUTORS.txt for Swift project authors
 //
 
+#if !SWT_NO_SNAPSHOT_TYPES
 /// A serializable snapshot of an `Error` value.
 ///
 /// This type conforms to `Error` as well, meaning it can be thrown and treated
@@ -40,3 +41,4 @@ extension ErrorSnapshot: CustomStringConvertible {}
 // MARK: - Codable
 
 extension ErrorSnapshot: Codable {}
+#endif

Sources/Testing/Issues/Issue.swift

@@ -194,6 +194,7 @@ extension Issue.Kind: CustomStringConvertible {
   }
 }
 
+#if !SWT_NO_SNAPSHOT_TYPES
 // MARK: - Snapshotting
 
 extension Issue {
@@ -476,3 +477,4 @@ extension Issue.Kind.Snapshot: CustomStringConvertible {
     }
   }
 }
+#endif

Sources/Testing/Parameterization/Test.Case.swift

@@ -160,6 +160,7 @@ extension Test.Case.Argument.ID: Codable {}
 extension Test.Parameter: Hashable {}
 extension Test.Case.Argument.ID: Hashable {}
 
+#if !SWT_NO_SNAPSHOT_TYPES
 // MARK: - Snapshotting
 
 extension Test.Case {
@@ -215,3 +216,4 @@ extension Test.Case.Argument {
     }
   }
 }
+#endif

Sources/Testing/Running/Runner.Plan.swift

@@ -303,6 +303,7 @@ extension Runner.Plan {
   }
 }
 
+#if !SWT_NO_SNAPSHOT_TYPES
 // MARK: - Snapshotting
 
 extension Runner.Plan {
@@ -430,3 +431,4 @@ extension Runner.Plan.Action {
     }
   }
 }
+#endif

Sources/Testing/Test.swift

@@ -271,6 +271,7 @@ extension Test: Equatable, Hashable {
   }
 }
 
+#if !SWT_NO_SNAPSHOT_TYPES
 // MARK: - Snapshotting
 
 extension Test {
@@ -388,3 +389,4 @@ extension Test {
     }
   }
 }
+#endif