Store test content in a custom metadata section.

Documentation/ABI/TestContent.md

@@ -75,16 +75,16 @@ struct SWTTestContentRecord {
 };
 ```
 
-Do not use the `__TestContentRecord` typealias defined in the testing library.
-This type exists to support the testing library's macros and may change in the
-future (e.g. to accomodate a generic argument or to make use of one of the
-reserved fields.)
+Do not use the `__TestContentRecord` or `__TestContentRecordAccessor` type
+aliases defined in the testing library. These types exist to support the testing
+library's macros and may change in the future (e.g. to accomodate a generic
+argument or to make use of a reserved field.)
 
-Instead, define your own copy of this type where needed—you can copy the
-definition above _verbatim_. If your test record type's `context` field (as
+Instead, define your own copy of these types where needed—you can copy the
+definitions above _verbatim_. If your test record type's `context` field (as
 described below) is a pointer type, make sure to change its type in your version
 of `TestContentRecord` accordingly so that, on systems with pointer
-authentication enabled, the pointer is correctly resigned at load time.
+authentication enabled, the pointer is correctly re-signed at load time.
 
 ### Record content
 

Documentation/Porting.md

@@ -145,8 +145,10 @@ to load that information:
 +  let resourceName: Str255 = switch kind {
 +  case .testContent:
 +    "__swift5_tests"
++#if !SWT_NO_LEGACY_TEST_DISCOVERY
 +  case .typeMetadata:
 +    "__swift5_types"
++#endif
 +  }
 +
 +  let oldRefNum = CurResFile()
@@ -219,15 +221,19 @@ diff --git a/Sources/_TestingInternals/Discovery.cpp b/Sources/_TestingInternals
 +#elif defined(macintosh)
 +extern "C" const char testContentSectionBegin __asm__("...");
 +extern "C" const char testContentSectionEnd __asm__("...");
++#if !defined(SWT_NO_LEGACY_TEST_DISCOVERY)
 +extern "C" const char typeMetadataSectionBegin __asm__("...");
 +extern "C" const char typeMetadataSectionEnd __asm__("...");
++#endif
  #else
  #warning Platform-specific implementation missing: Runtime test discovery unavailable (static)
  static const char testContentSectionBegin = 0;
  static const char& testContentSectionEnd = testContentSectionBegin;
+ #if !defined(SWT_NO_LEGACY_TEST_DISCOVERY)
  static const char typeMetadataSectionBegin = 0;
  static const char& typeMetadataSectionEnd = testContentSectionBegin;
  #endif
+ #endif
 ```
 
 These symbols must have unique addresses corresponding to the first byte of the

Package.swift

@@ -156,6 +156,8 @@ extension Array where Element == PackageDescription.SwiftSetting {
       .enableExperimentalFeature("AccessLevelOnImport"),
       .enableUpcomingFeature("InternalImportsByDefault"),
 
+      .enableExperimentalFeature("SymbolLinkageMarkers"),
+
       .define("SWT_TARGET_OS_APPLE", .when(platforms: [.macOS, .iOS, .macCatalyst, .watchOS, .tvOS, .visionOS])),
 
       .define("SWT_NO_EXIT_TESTS", .when(platforms: [.iOS, .watchOS, .tvOS, .visionOS, .wasi, .android])),

Sources/Testing/Discovery+Platform.swift

@@ -27,8 +27,10 @@ struct SectionBounds: Sendable {
     /// The test content metadata section.
     case testContent
 
+#if !SWT_NO_LEGACY_TEST_DISCOVERY
     /// The type metadata section.
     case typeMetadata
+#endif
   }
 
   /// All section bounds of the given kind found in the current process.
@@ -60,8 +62,10 @@ extension SectionBounds.Kind {
     switch self {
     case .testContent:
       ("__DATA_CONST", "__swift5_tests")
+#if !SWT_NO_LEGACY_TEST_DISCOVERY
     case .typeMetadata:
       ("__TEXT", "__swift5_types")
+#endif
     }
   }
 }
@@ -101,9 +105,8 @@ private let _startCollectingSectionBounds: Void = {
       var size = CUnsignedLong(0)
       if let start = getsectiondata(mh, segmentName.utf8Start, sectionName.utf8Start, &size), size > 0 {
         let buffer = UnsafeRawBufferPointer(start: start, count: Int(clamping: size))
-        let sb = SectionBounds(imageAddress: mh, buffer: buffer)
         _sectionBounds.withLock { sectionBounds in
-          sectionBounds[kind]!.append(sb)
+          sectionBounds[kind]!.append(SectionBounds(imageAddress: mh, buffer: buffer))
         }
       }
     }
@@ -165,8 +168,10 @@ private func _sectionBounds(_ kind: SectionBounds.Kind) -> [SectionBounds] {
       let range = switch context.pointee.kind {
       case .testContent:
         sections.swift5_tests
+#if !SWT_NO_LEGACY_TEST_DISCOVERY
       case .typeMetadata:
         sections.swift5_type_metadata
+#endif
       }
       let start = UnsafeRawPointer(bitPattern: range.start)
       let size = Int(clamping: range.length)
@@ -255,8 +260,10 @@ private func _sectionBounds(_ kind: SectionBounds.Kind) -> some Sequence<Section
   let sectionName = switch kind {
   case .testContent:
     ".sw5test"
+#if !SWT_NO_LEGACY_TEST_DISCOVERY
   case .typeMetadata:
     ".sw5tymd"
+#endif
   }
   return HMODULE.all.lazy.compactMap { _findSection(named: sectionName, in: $0) }
 }

Sources/Testing/Discovery.swift

@@ -49,6 +49,17 @@ public typealias __TestContentRecord = (
   reserved2: UInt
 )
 
+/// Compare two move-only types.
+///
+/// This operator is provided because the Swift standard library does not yet
+/// provide a `==` operator for move-only types. ([134276458](rdar://134276458))
+///
+/// - Warning: This operator is used to implement the `#expect(exitsWith:)`
+///   macro. Do not use it directly. It will be removed in a future update.
+public func ==(__lhs: (some ~Copyable).Type, rhs: (some ~Copyable).Type) -> Bool {
+  TypeInfo(describing: __lhs) == TypeInfo(describing: rhs)
+}
+
 // MARK: -
 
 /// A protocol describing a type that can be stored as test content at compile

Sources/Testing/ExitTests/ExitTest.swift

@@ -247,11 +247,15 @@ extension ExitTest {
       }
     }
 
+#if !SWT_NO_LEGACY_TEST_DISCOVERY
     // Call the legacy lookup function that discovers tests embedded in types.
     return types(withNamesContaining: exitTestContainerTypeNameMagic).lazy
       .compactMap { $0 as? any __ExitTestContainer.Type }
       .first { $0.__id == id }
       .map { ExitTest(__identifiedBy: $0.__id, body: $0.__body) }
+#else
+    return nil
+#endif
   }
 }
 

Sources/Testing/Test+Discovery+Legacy.swift

@@ -10,6 +10,7 @@
 
 private import _TestingInternals
 
+#if !SWT_NO_LEGACY_TEST_DISCOVERY
 /// A protocol describing a type that contains tests.
 ///
 /// - Warning: This protocol is used to implement the `@Test` macro. Do not use
@@ -60,3 +61,4 @@ func types(withNamesContaining nameSubstring: String) -> some Sequence<Any.Type>
       .map { unsafeBitCast($0, to: Any.Type.self) }
   }
 }
+#endif

Sources/Testing/Test+Discovery.swift

@@ -53,6 +53,7 @@ extension Test {
       // the legacy and new mechanisms, but we can set an environment variable
       // to explicitly select one or the other. When we remove legacy support,
       // we can also remove this enumeration and environment variable check.
+#if !SWT_NO_LEGACY_TEST_DISCOVERY
       let (useNewMode, useLegacyMode) = switch Environment.flag(named: "SWT_USE_LEGACY_TEST_DISCOVERY") {
       case .none:
         (true, true)
@@ -61,6 +62,9 @@ extension Test {
       case .some(false):
         (true, false)
       }
+#else
+      let useNewMode = true
+#endif
 
       // Walk all test content and gather generator functions, then call them in
       // a task group and collate their results.
@@ -79,6 +83,7 @@ extension Test {
         }
       }
 
+#if !SWT_NO_LEGACY_TEST_DISCOVERY
       // Perform legacy test discovery if needed.
       if useLegacyMode && result.isEmpty {
         let types = types(withNamesContaining: testContainerTypeNameMagic).lazy
@@ -92,6 +97,7 @@ extension Test {
           result = await taskGroup.reduce(into: result) { $0.formUnion($1) }
         }
       }
+#endif
 
       return result
     }

Sources/TestingMacros/CMakeLists.txt

@@ -87,6 +87,7 @@ target_sources(TestingMacros PRIVATE
   Support/Additions/DeclGroupSyntaxAdditions.swift
   Support/Additions/EditorPlaceholderExprSyntaxAdditions.swift
   Support/Additions/FunctionDeclSyntaxAdditions.swift
+  Support/Additions/IntegerLiteralExprSyntaxAdditions.swift
   Support/Additions/MacroExpansionContextAdditions.swift
   Support/Additions/TokenSyntaxAdditions.swift
   Support/Additions/TriviaPieceAdditions.swift
@@ -103,6 +104,7 @@ target_sources(TestingMacros PRIVATE
   Support/DiagnosticMessage+Diagnosing.swift
   Support/SourceCodeCapturing.swift
   Support/SourceLocationGeneration.swift
+  Support/TestContentGeneration.swift
   TagMacro.swift
   TestDeclarationMacro.swift
   TestingMacrosMain.swift)

Sources/TestingMacros/ConditionMacro.swift

@@ -435,11 +435,44 @@ extension ExitTestConditionMacro {
 
     // Create a local type that can be discovered at runtime and which contains
     // the exit test body.
-    let enumName = context.makeUniqueName("__🟠$exit_test_body__")
+    let enumName = context.makeUniqueName("")
+    let testContentRecordDecl = makeTestContentRecordDecl(
+      named: .identifier("testContentRecord"),
+      in: TypeSyntax(IdentifierTypeSyntax(name: enumName)),
+      ofKind: .exitTest,
+      accessingWith: .identifier("accessor")
+    )
+    decls.append(
+      """
+      #if hasFeature(SymbolLinkageMarkers)
+      @available(*, deprecated, message: "This type is an implementation detail of the testing library. Do not use it directly.")
+      enum \(enumName) {
+        private static let accessor: Testing.__TestContentRecordAccessor = { outValue, type, hint in
+          guard type.load(as: (any ~Swift.Copyable.Type).self) == Testing.__ExitTest.self else {
+            return false
+          }
+          let id = \(exitTestIDExpr)
+          if let hintedID = hint?.load(as: Testing.__ExitTest.ID.self), hintedID != id {
+            return false
+          }
+          let outValue = outValue.assumingMemoryBound(to: Testing.__ExitTest.self)
+          outValue.initialize(to: .init(__identifiedBy: id, body: \(bodyThunkName)))
+          return true
+        }
+
+        \(testContentRecordDecl)
+      }
+      #endif
+      """
+    )
+
+#if !SWT_NO_LEGACY_TEST_DISCOVERY
+    // Emit a legacy type declaration if SymbolLinkageMarkers is off.
+    let legacyEnumName = context.makeUniqueName("__🟠$exit_test_body__")
     decls.append(
       """
       @available(*, deprecated, message: "This type is an implementation detail of the testing library. Do not use it directly.")
-      enum \(enumName): Testing.__ExitTestContainer, Sendable {
+      enum \(legacyEnumName): Testing.__ExitTestContainer, Sendable {
         static var __id: Testing.__ExitTest.ID {
           \(exitTestIDExpr)
         }
@@ -449,12 +482,16 @@ extension ExitTestConditionMacro {
       }
       """
     )
+#endif
 
     arguments[trailingClosureIndex].expression = ExprSyntax(
       ClosureExprSyntax {
         for decl in decls {
-          CodeBlockItemSyntax(item: .decl(decl))
-            .with(\.trailingTrivia, .newline)
+          CodeBlockItemSyntax(
+            leadingTrivia: .newline,
+            item: .decl(decl),
+            trailingTrivia: .newline
+          )
         }
       }
     )

Sources/TestingMacros/SuiteDeclarationMacro.swift

@@ -127,6 +127,54 @@ public struct SuiteDeclarationMacro: MemberMacro, PeerMacro, Sendable {
     // Parse the @Suite attribute.
     let attributeInfo = AttributeInfo(byParsing: suiteAttribute, on: declaration, in: context)
 
+    let generatorName = context.makeUniqueName("generator")
+    result.append(
+      """
+      @available(*, deprecated, message: "This property is an implementation detail of the testing library. Do not use it directly.")
+      @Sendable private static func \(generatorName)() async -> Testing.Test {
+        .__type(
+          \(declaration.type.trimmed).self,
+          \(raw: attributeInfo.functionArgumentList(in: context))
+        )
+      }
+      """
+    )
+
+    let accessorName = context.makeUniqueName("accessor")
+    let accessorDecl: DeclSyntax = """
+    @available(*, deprecated, message: "This property is an implementation detail of the testing library. Do not use it directly.")
+    private static let \(accessorName): Testing.__TestContentRecordAccessor = { outValue, type, _ in
+      typealias Generator = @Sendable () async -> Testing.Test
+      guard type.load(as: Any.Type.self) == Generator.self else {
+        return false
+      }
+      let outValue = outValue.assumingMemoryBound(to: Generator.self)
+      outValue.initialize(to: \(generatorName))
+      return true
+    }
+    """
+
+    let testContentRecordDecl = makeTestContentRecordDecl(
+      named: context.makeUniqueName("testContentRecord"),
+      in: declaration.type,
+      ofKind: .testDeclaration,
+      accessingWith: accessorName,
+      context: attributeInfo.testContentRecordFlags
+    )
+
+    result.append(
+      """
+      #if hasFeature(SymbolLinkageMarkers)
+      \(accessorDecl)
+
+      \(testContentRecordDecl)
+      #endif
+      """
+    )
+
+#if !SWT_NO_LEGACY_TEST_DISCOVERY
+    // Emit a legacy type declaration if SymbolLinkageMarkers is off.
+    //
     // The emitted type must be public or the compiler can optimize it away
     // (since it is not actually used anywhere that the compiler can see.)
     //
@@ -143,16 +191,14 @@ public struct SuiteDeclarationMacro: MemberMacro, PeerMacro, Sendable {
       @available(*, deprecated, message: "This type is an implementation detail of the testing library. Do not use it directly.")
       enum \(enumName): Testing.__TestContainer {
         static var __tests: [Testing.Test] {
-          get async {[
-            .__type(
-              \(declaration.type.trimmed).self,
-              \(raw: attributeInfo.functionArgumentList(in: context))
-            )
-          ]}
+          get async {
+            [await \(generatorName)()]
+          }
         }
       }
       """
     )
+#endif
 
     return result
   }

Sources/TestingMacros/Support/Additions/IntegerLiteralExprSyntaxAdditions.swift

@@ -0,0 +1,18 @@
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2024 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for Swift project authors
+//
+
+import SwiftSyntax
+
+extension IntegerLiteralExprSyntax {
+  init(_ value: some BinaryInteger, radix: IntegerLiteralExprSyntax.Radix = .decimal) {
+    let stringValue = "\(radix.literalPrefix)\(String(value, radix: radix.size))"
+    self.init(literal: .integerLiteral(stringValue))
+  }
+}

Sources/TestingMacros/Support/Additions/TokenSyntaxAdditions.swift

@@ -47,3 +47,14 @@ extension TokenSyntax {
     return nil
   }
 }
+
+/// The `static` keyword, if `typeName` is not `nil`.
+///
+/// - Parameters:
+///   - typeName: The name of the type containing the macro being expanded.
+///
+/// - Returns: A token representing the `static` keyword, or one representing
+///   nothing if `typeName` is `nil`.
+func staticKeyword(for typeName: TypeSyntax?) -> TokenSyntax {
+  (typeName != nil) ? .keyword(.static) : .unknown("")
+}