Merge pull request #1887 from bnbarham/provide-extension-type-fallback

Plugin should keep handling the conformance macro role

Author: bnbarham

Sources/SwiftCompilerPluginMessageHandling/Macros.swift

@@ -168,7 +168,7 @@ private extension MacroRole {
     case .memberAttribute: self = .memberAttribute
     case .member: self = .member
     case .peer: self = .peer
-    case .conformance: self = .conformance
+    case .conformance: self = .extension
     case .codeItem: self = .codeItem
     case .extension: self = .extension
     }

Sources/SwiftSyntaxMacroExpansion/MacroExpansion.swift

@@ -251,7 +251,13 @@ public func expandAttachedMacroWithoutCollapsing<Context: MacroExpansionContext>
         throw MacroExpansionError.declarationNotDeclGroup
       }
 
-      guard let extendedType = extendedType else {
+      let extensionOf: TypeSyntax
+      if let extendedType {
+        extensionOf = extendedType
+      } else if let identified = declarationNode.asProtocol(IdentifiedDeclSyntax.self) {
+        // Fallback for old compilers with a new plugin, where
+        extensionOf = TypeSyntax(SimpleTypeIdentifierSyntax(name: identified.identifier))
+      } else {
         throw MacroExpansionError.noExtendedTypeSyntax
       }
 
@@ -260,7 +266,7 @@ public func expandAttachedMacroWithoutCollapsing<Context: MacroExpansionContext>
       let extensions = try attachedMacro.expansion(
         of: attributeNode,
         attachedTo: declGroup,
-        providingExtensionsOf: extendedType,
+        providingExtensionsOf: extensionOf,
         conformingTo: protocols,
         in: context
       )

Sources/SwiftSyntaxMacros/MacroProtocols/ConformanceMacro.swift

@@ -51,13 +51,13 @@ extension ConformanceMacro {
     for (proto, whereClause) in newConformances {
       let decl: DeclSyntax =
         """
-        extension \(type.trimmed): \(proto) {}
+        extension \(type.trimmed): \(proto.trimmed) {}
         """
 
       var extensionDecl = decl.cast(ExtensionDeclSyntax.self)
 
       if let whereClause {
-        extensionDecl = extensionDecl.with(\.genericWhereClause, whereClause)
+        extensionDecl = extensionDecl.with(\.genericWhereClause, whereClause.trimmed)
       }
 
       extensions.append(extensionDecl)