Merge pull request #68032 from DougGregor/supersede-pre-macro-expansion-implied-conformances-5.9

Author: DougGregor

include/swift/AST/DeclContext.h

@@ -150,15 +150,15 @@ enum class ConformanceEntryKind : unsigned {
   /// Explicitly specified.
   Explicit,
 
+  /// The conformance is generated by a macro that has not been
+  /// expanded yet.
+  PreMacroExpansion,
+
   /// Implicitly synthesized.
   Synthesized,
 
   /// Implied by an explicitly-specified conformance.
   Implied,
-
-  /// The conformance is generated by a macro that has not been
-  /// expanded yet.
-  PreMacroExpansion,
 };
 
 /// Describes the kind of conformance lookup desired.

lib/AST/ConformanceLookupTable.h

@@ -147,7 +147,7 @@ class ConformanceLookupTable : public ASTAllocated<ConformanceLookupTable> {
     ///
     /// The only difference between the ranking kind and the kind is
     /// that implied conformances originating from a synthesized
-    /// conformance are considered to be synthesized (which has a
+    /// or pre-macro-expansion conformance are considered to be synthesized (which has a
     /// lower ranking).
     ConformanceEntryKind getRankingKind() const {
       switch (auto kind = getKind()) {
@@ -157,11 +157,22 @@ class ConformanceLookupTable : public ASTAllocated<ConformanceLookupTable> {
       case ConformanceEntryKind::PreMacroExpansion:
         return kind;
 
-      case ConformanceEntryKind::Implied:
-        return (getImpliedSource()->getDeclaredConformance()->getKind()
-                  == ConformanceEntryKind::Synthesized)
-                 ? ConformanceEntryKind::Synthesized
-                 : ConformanceEntryKind::Implied;
+      case ConformanceEntryKind::Implied: {
+        auto impliedSourceKind =
+        getImpliedSource()->getDeclaredConformance()->getKind();
+        switch (impliedSourceKind) {
+          case ConformanceEntryKind::Synthesized:
+          case ConformanceEntryKind::PreMacroExpansion:
+            return impliedSourceKind;
+
+          case ConformanceEntryKind::Explicit:
+          case ConformanceEntryKind::Inherited:
+            return ConformanceEntryKind::Implied;
+
+          case ConformanceEntryKind::Implied:
+            return getImpliedSource()->getRankingKind();
+        }
+      }
       }
 
       llvm_unreachable("Unhandled ConformanceEntryKind in switch.");

lib/Macros/Sources/SwiftMacros/OptionSetMacro.swift

@@ -123,27 +123,25 @@ public struct OptionSetMacro {
   }
 }
 
-extension OptionSetMacro: ConformanceMacro {
-  public static func expansion<
-    Decl: DeclGroupSyntax,
-    Context: MacroExpansionContext
-  >(
+extension OptionSetMacro: ExtensionMacro {
+  public static func expansion(
     of attribute: AttributeSyntax,
-    providingConformancesOf decl: Decl,
-    in context: Context
-  ) throws -> [(TypeSyntax, GenericWhereClauseSyntax?)] {
-    // Decode the expansion arguments.
-    guard let (structDecl, _, _) = decodeExpansion(of: attribute, attachedTo: decl, in: context) else {
-      return []
-    }
-
+    attachedTo decl: some DeclGroupSyntax,
+    providingExtensionsOf type: some TypeSyntaxProtocol,
+    conformingTo protocols: [TypeSyntax],
+    in context: some MacroExpansionContext
+  ) throws -> [ExtensionDeclSyntax] {
     // If there is an explicit conformance to OptionSet already, don't add one.
-    if let inheritedTypes = structDecl.inheritanceClause?.inheritedTypeCollection,
-       inheritedTypes.contains(where: { inherited in inherited.typeName.trimmedDescription == "OptionSet" }) {
+    if protocols.isEmpty {
       return []
     }
 
-    return [("OptionSet", nil)]
+    let ext: DeclSyntax =
+      """
+      extension \(type.trimmed): OptionSet {}
+      """
+
+    return [ext.cast(ExtensionDeclSyntax.self)]
   }
 }
 

test/Index/index_macros.swift

@@ -207,14 +207,16 @@ public struct SomeAccessorMacro: AccessorMacro {
   }
 }
 
-public struct SomeConformanceMacro: ConformanceMacro {
+public struct SomeConformanceMacro: ExtensionMacro {
   public static func expansion(
     of node: AttributeSyntax,
-    providingConformancesOf decl: some DeclGroupSyntax,
+    attachedTo: some DeclGroupSyntax,
+    providingExtensionsOf type: some TypeSyntaxProtocol,
+    conformingTo protocols: [TypeSyntax],
     in context: some MacroExpansionContext
-  ) throws -> [(TypeSyntax, GenericWhereClauseSyntax?)] {
-    let protocolName: TypeSyntax = "TestProto"
-    return [(protocolName, nil)]
+  ) throws -> [ExtensionDeclSyntax] {
+    let ext: DeclSyntax = "extension \(type.trimmed): TestProto {}"
+    return [ext.cast(ExtensionDeclSyntax.self)]
   }
 }
 

test/Macros/Inputs/syntax_macro_definitions.swift

@@ -1344,14 +1344,16 @@ public struct EmptyPeerMacro: PeerMacro {
   }
 }
 
-public struct EquatableMacro: ConformanceMacro {
+public struct EquatableMacro: ExtensionMacro {
   public static func expansion(
     of node: AttributeSyntax,
-    providingConformancesOf decl: some DeclGroupSyntax,
+    attachedTo: some DeclGroupSyntax,
+    providingExtensionsOf type: some TypeSyntaxProtocol,
+    conformingTo protocols: [TypeSyntax],
     in context: some MacroExpansionContext
-  ) throws -> [(TypeSyntax, GenericWhereClauseSyntax?)] {
-    let protocolName: TypeSyntax = "Equatable"
-    return [(protocolName, nil)]
+  ) throws -> [ExtensionDeclSyntax] {
+    let ext: DeclSyntax = "extension \(type.trimmed): Equatable {}"
+    return [ext.cast(ExtensionDeclSyntax.self)]
   }
 }
 
@@ -1412,34 +1414,50 @@ public struct ConformanceViaExtensionMacro: ExtensionMacro {
   }
 }
 
-public struct HashableMacro: ConformanceMacro {
+public struct HashableMacro: ExtensionMacro {
+  public static func expansion(
+    of node: AttributeSyntax,
+    attachedTo: some DeclGroupSyntax,
+    providingExtensionsOf type: some TypeSyntaxProtocol,
+    conformingTo protocols: [TypeSyntax],
+    in context: some MacroExpansionContext
+  ) throws -> [ExtensionDeclSyntax] {
+    let ext: DeclSyntax = "extension \(type.trimmed): Hashable {}"
+    return [ext.cast(ExtensionDeclSyntax.self)]
+  }
+}
+
+public struct ImpliesHashableMacro: ExtensionMacro {
   public static func expansion(
     of node: AttributeSyntax,
-    providingConformancesOf decl: some DeclGroupSyntax,
+    attachedTo: some DeclGroupSyntax,
+    providingExtensionsOf type: some TypeSyntaxProtocol,
+    conformingTo protocols: [TypeSyntax],
     in context: some MacroExpansionContext
-  ) throws -> [(TypeSyntax, GenericWhereClauseSyntax?)] {
-    let protocolName: TypeSyntax = "Hashable"
-    return [(protocolName, nil)]
+  ) throws -> [ExtensionDeclSyntax] {
+    let ext: DeclSyntax = "extension \(type.trimmed): ImpliesHashable {}"
+    return [ext.cast(ExtensionDeclSyntax.self)]
   }
 }
 
-public struct DelegatedConformanceMacro: ConformanceMacro, MemberMacro {
+public struct DelegatedConformanceMacro: ExtensionMacro, MemberMacro {
   public static func expansion(
     of node: AttributeSyntax,
-    providingConformancesOf decl: some DeclGroupSyntax,
+    attachedTo: some DeclGroupSyntax,
+    providingExtensionsOf type: some TypeSyntaxProtocol,
+    conformingTo protocols: [TypeSyntax],
     in context: some MacroExpansionContext
-  ) throws -> [(TypeSyntax, GenericWhereClauseSyntax?)] {
-    let protocolName: TypeSyntax = "P"
+  ) throws -> [ExtensionDeclSyntax] {
     let conformance: DeclSyntax =
       """
-      extension Placeholder where Element: P {}
+      extension \(type.trimmed): P where Element: P {}
       """
 
     guard let extensionDecl = conformance.as(ExtensionDeclSyntax.self) else {
       return []
     }
 
-    return [(protocolName, extensionDecl.genericWhereClause)]
+    return [extensionDecl]
   }
 
   public static func expansion(
@@ -1894,26 +1912,21 @@ public struct AddPeerStoredPropertyMacro: PeerMacro, Sendable {
   }
 }
 
-public struct InitializableMacro: ConformanceMacro, MemberMacro {
+public struct InitializableMacro: ExtensionMacro {
   public static func expansion(
     of node: AttributeSyntax,
-    providingConformancesOf decl: some DeclGroupSyntax,
-    in context: some MacroExpansionContext
-  ) throws -> [(TypeSyntax, GenericWhereClauseSyntax?)] {
-    return [("Initializable", nil)]
-  }
-
-  public static func expansion(
-    of node: AttributeSyntax,
-    providingMembersOf decl: some DeclGroupSyntax,
+    attachedTo: some DeclGroupSyntax,
+    providingExtensionsOf type: some TypeSyntaxProtocol,
+    conformingTo protocols: [TypeSyntax],
     in context: some MacroExpansionContext
-  ) throws -> [DeclSyntax] {
-    let requirement: DeclSyntax =
+  ) throws -> [ExtensionDeclSyntax] {
+    let ext: DeclSyntax = 
       """
-      init(value: Int) {}
+      extension \(type.trimmed): Initializable {
+        init(value: Int) {}
+      }
       """
-
-    return [requirement]
+    return [ext.cast(ExtensionDeclSyntax.self)]
   }
 }
 

test/Macros/macro_expand_extensions.swift

@@ -10,6 +10,9 @@
 // RUN: not %target-swift-frontend -enable-experimental-feature ExtensionMacros -swift-version 5 -typecheck -load-plugin-library %t/%target-library-name(MacroDefinition) -module-name MacroUser -DTEST_DIAGNOSTICS -serialize-diagnostics-path %t/macro_expand.dia %s -emit-macro-expansion-files no-diagnostics
 // RUN: c-index-test -read-diagnostics %t/macro_expand.dia 2>&1 | %FileCheck -check-prefix CHECK-DIAGS %s
 
+// Ensure that we can serialize this file as a module.
+// RUN: %target-swift-frontend -swift-version 5 -load-plugin-library %t/%target-library-name(MacroDefinition) %s -I %t -disable-availability-checking -emit-module -o %t/MyModule.swiftmodule -enable-testing
+
 // RUN: %target-build-swift -enable-experimental-feature ExtensionMacros -swift-version 5 -load-plugin-library %t/%target-library-name(MacroDefinition) %s -o %t/main -module-name MacroUser -swift-version 5 -emit-tbd -emit-tbd-path %t/MacroUser.tbd -I %t
 // RUN: %target-codesign %t/main
 // RUN: %target-run %t/main | %FileCheck %s
@@ -198,3 +201,18 @@ func requiresEquatable<T: Equatable>(_: T) { }
 func testHasPropertyWrappers(hpw: HasPropertyWrappers) {
   requiresEquatable(hpw)
 }
+
+// Check that conformances implied by a macro-defined conformance are serialized
+// without issue.
+public protocol ImpliesHashable: Hashable { }
+
+@attached(extension, conformances: ImpliesHashable)
+macro ImpliesHashable() = #externalMacro(module: "MacroDefinition", type: "ImpliesHashableMacro")
+
+func requiresHashable<T: Hashable>(_: T) { }
+func testMakeMeHashable(mmh: MakeMeHashable, dict: [MakeMeHashable: Int]) {
+  requiresHashable(mmh)
+}
+
+@ImpliesHashable
+public struct MakeMeHashable { }

test/Macros/top_level_freestanding.swift

@@ -117,8 +117,7 @@ macro Empty<T>(_ closure: () -> T) = #externalMacro(module: "MacroDefinition", t
   S(a: 10, b: 10)
 }
 
-@attached(extension, conformances: Initializable)
-@attached(member, names: named(init))
+@attached(extension, conformances: Initializable, names: named(init))
 macro Initializable() = #externalMacro(module: "MacroDefinition", type: "InitializableMacro")
 
 protocol Initializable {