Build the side target in CMake but not in the package; the package ought to use the copy from the toolchain rather than rolling its own which other libraries won't know to link to

Author: grynspan

Package.swift

@@ -105,14 +105,6 @@ let package = Package(
       )
     )
 
-    result.append(
-      .library(
-        name: "_Testing_ExperimentalInfrastructure",
-        type: .dynamic,
-        targets: ["_Testing_ExperimentalInfrastructure"]
-      )
-    )
-
     return result
   }(),
 
@@ -134,7 +126,6 @@ let package = Package(
       dependencies: [
         "_TestDiscovery",
         "_TestingInternals",
-        "_Testing_ExperimentalInfrastructure",
         "TestingMacros",
       ],
       exclude: ["CMakeLists.txt", "Testing.swiftcrossimport"],
@@ -218,13 +209,6 @@ let package = Package(
       cxxSettings: .packageSettings,
       swiftSettings: .packageSettings + .enableLibraryEvolution()
     ),
-    .target(
-      name: "_Testing_ExperimentalInfrastructure",
-      dependencies: ["_TestingInternals",],
-      exclude: ["CMakeLists.txt"],
-      cxxSettings: .packageSettings,
-      swiftSettings: .packageSettings + .enableLibraryEvolution()
-    ),
 
     // Cross-import overlays (not supported by Swift Package Manager)
     .target(

Sources/CMakeLists.txt

@@ -104,7 +104,7 @@ endif()
 include(AvailabilityDefinitions)
 include(CompilerSettings)
 add_subdirectory(_TestDiscovery)
-add_subdirectory(_Testing_ExperimentalInfrastructure)
+add_subdirectory(_TestingInfrastructure)
 add_subdirectory(_TestingInternals)
 add_subdirectory(Overlays)
 add_subdirectory(Testing)

Sources/Testing/Events/Event+FallbackHandler.swift

@@ -8,7 +8,9 @@
 // See https://swift.org/CONTRIBUTORS.txt for Swift project authors
 //
 
-private import _Testing_ExperimentalInfrastructure
+#if canImport(_TestingInfrastructure)
+private import _TestingInfrastructure
+#endif
 
 extension Event {
   /// Attempt to handle an event encoded as JSON as if it had been generated in
@@ -62,6 +64,7 @@ extension Event {
     }
   }
 
+#if canImport(_TestingInfrastructure)
   /// The fallback event handler to set when Swift Testing is the active testing
   /// library.
   private static let _fallbackEventHandler: FallbackEventHandler = { recordJSONSchemaVersionNumber, recordJSONBaseAddress, recordJSONByteCount, _ in
@@ -73,10 +76,15 @@ extension Event {
       try! Self.handle(recordJSON, encodedWith: abi)
     }
   }
+#endif
 
   /// The implementation of ``installFallbackEventHandler()``.
   private static let _installFallbackHandler: Bool = {
-    _Testing_ExperimentalInfrastructure.installFallbackEventHandler(Self._fallbackEventHandler)
+#if canImport(_TestingInfrastructure)
+    _swift_testing_installFallbackEventHandler(Self._fallbackEventHandler)
+#else
+    false
+#endif
   }()
 
   /// Install the testing library's fallback event handler.
@@ -95,7 +103,8 @@ extension Event {
   ///   currently-installed handler belongs to the testing library, returns
   ///   `false`.
   borrowing func postToFallbackHandler(in context: borrowing Context) -> Bool {
-    guard let fallbackEventHandler = _Testing_ExperimentalInfrastructure.fallbackEventHandler() else {
+#if canImport(_TestingInfrastructure)
+    guard let fallbackEventHandler = _swift_testing_getFallbackEventHandler() else {
       // No fallback event handler is installed.
       return false
     }
@@ -116,5 +125,8 @@ extension Event {
     }
     encodeAndInvoke(self, context)
     return true
+#else
+    return false
+#endif
   }
 }

Sources/_Testing_ExperimentalInfrastructure/CMakeLists.txt renamed to Sources/_TestingInfrastructure/CMakeLists.txt

@@ -6,19 +6,19 @@
 # See http://swift.org/LICENSE.txt for license information
 # See http://swift.org/CONTRIBUTORS.txt for Swift project authors
 
-add_library(_Testing_ExperimentalInfrastructure
+add_library(_TestingInfrastructure
   FallbackEventHandler.swift)
 
-target_link_libraries(_Testing_ExperimentalInfrastructure PRIVATE
+target_link_libraries(_TestingInfrastructure PRIVATE
   _TestingInternals)
 if(NOT BUILD_SHARED_LIBS)
   # When building a static library, tell clients to autolink the internal
   # libraries.
   target_compile_options(Testing PRIVATE
     "SHELL:-Xfrontend -public-autolink-library -Xfrontend _TestingInternals")
 endif()
-target_compile_options(_Testing_ExperimentalInfrastructure PRIVATE
+target_compile_options(_TestingInfrastructure PRIVATE
   -enable-library-evolution
-  -emit-module-interface -emit-module-interface-path $<TARGET_PROPERTY:_Testing_ExperimentalInfrastructure,Swift_MODULE_DIRECTORY>/_Testing_ExperimentalInfrastructure.swiftinterface)
+  -emit-module-interface -emit-module-interface-path $<TARGET_PROPERTY:_TestingInfrastructure,Swift_MODULE_DIRECTORY>/_TestingInfrastructure.swiftinterface)
 
-_swift_testing_install_target(_Testing_ExperimentalInfrastructure)
+_swift_testing_install_target(_TestingInfrastructure)

Sources/_Testing_ExperimentalInfrastructure/FallbackEventHandler.swift renamed to Sources/_TestingInfrastructure/FallbackEventHandler.swift

@@ -54,9 +54,9 @@ package typealias FallbackEventHandler = @Sendable @convention(c) (
 ///   to calls to ``setFallbackEventHandler(_:)``. If you need to atomically
 ///   exchange the previous value with a new value, call
 ///   ``setFallbackEventHandler(_:)`` and store its returned value.
-@_cdecl("swift_testing_getFallbackEventHandler")
+@_cdecl("_swift_testing_getFallbackEventHandler")
 @usableFromInline
-package func fallbackEventHandler() -> FallbackEventHandler? {
+package func _swift_testing_getFallbackEventHandler() -> FallbackEventHandler? {
 #if SWT_TARGET_OS_APPLE && !SWT_NO_OS_UNFAIR_LOCK
   return _fallbackEventHandler.withUnsafeMutablePointers { fallbackEventHandler, lock in
     os_unfair_lock_lock(lock)
@@ -82,9 +82,9 @@ package func fallbackEventHandler() -> FallbackEventHandler? {
 /// The fallback event handler can only be installed once per process, typically
 /// by the first testing library to run. If this function has already been
 /// called and the handler set, it does not replace the previous handler.
-@_cdecl("swift_testing_installFallbackEventHandler")
+@_cdecl("_swift_testing_installFallbackEventHandler")
 @usableFromInline
-package func installFallbackEventHandler(_ handler: FallbackEventHandler) -> CBool {
+package func _swift_testing_installFallbackEventHandler(_ handler: FallbackEventHandler) -> CBool {
 #if SWT_TARGET_OS_APPLE && !SWT_NO_OS_UNFAIR_LOCK
   return _fallbackEventHandler.withUnsafeMutablePointers { fallbackEventHandler, lock in
     os_unfair_lock_lock(lock)

Tests/TestingTests/EventTests.swift

@@ -81,8 +81,8 @@ struct EventTests {
 
 // MARK: -
 
-#if canImport(Foundation)
-private import _Testing_ExperimentalInfrastructure
+#if canImport(_TestingInfrastructure) && canImport(Foundation)
+private import _TestingInfrastructure
 import Foundation
 
 private func MockXCTAssert(_ condition: Bool, _ message: String, _ sourceLocation: SourceLocation = #_sourceLocation) {