[Macro expansion] Detach arguments to macros consistently

Author: DougGregor

Sources/SwiftSyntaxMacros/MacroSystem.swift

@@ -134,13 +134,13 @@ class MacroApplication<Context: MacroExpansionContext>: SyntaxRewriter {
         do {
           if let macro = macro as? CodeItemMacro.Type {
             let expandedItemList = try macro.expansion(
-              of: exprExpansion,
+              of: exprExpansion.detach(in: context),
               in: context
             )
             newItems.append(contentsOf: expandedItemList)
           } else if let macro = macro as? DeclarationMacro.Type {
             let expandedItemList = try macro.expansion(
-              of: exprExpansion,
+              of: exprExpansion.detach(in: context),
               in: context
             )
             newItems.append(
@@ -150,7 +150,7 @@ class MacroApplication<Context: MacroExpansionContext>: SyntaxRewriter {
             )
           } else if let macro = macro as? ExpressionMacro.Type {
             let expandedExpr = try macro.expansion(
-              of: exprExpansion,
+              of: exprExpansion.detach(in: context),
               in: context
             )
             newItems.append(CodeBlockItemSyntax(item: .init(expandedExpr)))
@@ -190,7 +190,7 @@ class MacroApplication<Context: MacroExpansionContext>: SyntaxRewriter {
       {
         do {
           let expandedList = try freestandingMacro.expansion(
-            of: declExpansion,
+            of: declExpansion.detach(in: context),
             in: context
           )
 
@@ -297,8 +297,8 @@ class MacroApplication<Context: MacroExpansionContext>: SyntaxRewriter {
     for (accessorAttr, accessorMacro) in accessorMacroAttributes {
       do {
         let newAccessors = try accessorMacro.expansion(
-          of: accessorAttr,
-          providingAccessorsOf: visitedNode,
+          of: accessorAttr.detach(in: context),
+          providingAccessorsOf: visitedNode.detach(in: context),
           in: context
         )
 
@@ -367,7 +367,11 @@ extension MacroApplication {
     let macroAttributes = getMacroAttributes(attachedTo: decl, ofType: PeerMacro.Type.self)
     for (attribute, peerMacro) in macroAttributes {
       do {
-        let newPeers = try peerMacro.expansion(of: attribute, providingPeersOf: decl, in: context)
+        let newPeers = try peerMacro.expansion(
+          of: attribute.detach(in: context),
+          providingPeersOf: decl.detach(in: context),
+          in: context
+        )
         peers.append(contentsOf: newPeers)
       } catch {
         context.addDiagnostics(from: error, node: attribute)
@@ -388,8 +392,8 @@ extension MacroApplication {
       do {
         try newMembers.append(
           contentsOf: memberMacro.expansion(
-            of: attribute,
-            providingMembersOf: decl,
+            of: attribute.detach(in: context),
+            providingMembersOf: decl.detach(in: context),
             in: context
           )
         )
@@ -417,9 +421,9 @@ extension MacroApplication {
     #if false
     _openExistential(decl) { d in
       return try! macro.expansion(
-        of: attribute,
-        attachedTo: d,
-        annotating: member,
+        of: attribute.detach(in: context),
+        attachedTo: d.detach(in: context),
+        annotating: member.detach(in: context),
         in: context
       )
     }
@@ -444,9 +448,9 @@ extension MacroApplication {
 
         func expand<Decl: DeclGroupSyntax>(_ decl: Decl) throws -> [AttributeSyntax] {
           return try attributeMacro.expansion(
-            of: attribute,
-            attachedTo: decl,
-            providingAttributesFor: member.decl,
+            of: attribute.detach(in: context),
+            attachedTo: decl.detach(in: context),
+            providingAttributesFor: member.decl.detach(in: context),
             in: context
           )
         }

Sources/SwiftSyntaxMacros/Syntax+MacroEvaluation.swift

@@ -16,7 +16,7 @@ import SwiftSyntax
 extension SyntaxProtocol {
   /// Detach the current node and inform the macro expansion context,
   /// if it needs to know.
-  fileprivate func detach(in context: MacroExpansionContext) -> Self {
+  func detach(in context: MacroExpansionContext) -> Self {
     if let basicContext = context as? BasicMacroExpansionContext {
       return basicContext.detach(self)
     }

Tests/SwiftSyntaxMacrosTest/MacroSystemTests.swift

@@ -392,7 +392,7 @@ public struct AddCompletionHandler: PeerMacro {
           return true
         }
 
-        return attribute != node
+        return attribute.attributeName.description != node.attributeName.description
       } ?? []
     )