[ASTScope] Adjust parent location for peer macro to after its attached decl.

lib/AST/ASTScopeCreation.cpp

@@ -30,6 +30,7 @@
 #include "swift/AST/SourceFile.h"
 #include "swift/AST/Stmt.h"
 #include "swift/AST/TypeRepr.h"
+#include "swift/Parse/Lexer.h"
 #include "swift/Basic/Debug.h"
 #include "swift/Basic/STLExtras.h"
 #include "llvm/Support/Compiler.h"
@@ -262,10 +263,19 @@ ASTSourceFileScope::ASTSourceFileScope(SourceFile *SF,
     case MacroRole::Declaration:
     case MacroRole::Accessor:
     case MacroRole::MemberAttribute:
-    case MacroRole::Peer:
     case MacroRole::Conformance:
       parentLoc = expansion.getStartLoc();
       break;
+    case MacroRole::Peer: {
+      ASTContext &ctx = SF->getASTContext();
+      SourceManager &sourceMgr = ctx.SourceMgr;
+      const auto &generatedSourceInfo =
+          *sourceMgr.getGeneratedSourceInfo(*SF->getBufferID());
+
+      ASTNode node = ASTNode::getFromOpaqueValue(generatedSourceInfo.astNode);
+      parentLoc = Lexer::getLocForEndOfToken(sourceMgr, node.getEndLoc());
+      break;
+    }
     case MacroRole::Member: {
       // For synthesized member macros, take the end loc of the
       // enclosing declaration (before the closing brace), because

test/Macros/Inputs/macro_library.swift

@@ -35,3 +35,6 @@ public macro ObservableProperty() = #externalMacro(module: "MacroDefinition", ty
 
 @attached(peer, names: overloaded)
 public macro addCompletionHandler() = #externalMacro(module: "MacroDefinition", type: "AddCompletionHandler")
+
+@attached(peer, names: suffixed(Builder))
+public macro AddClassReferencingSelf() = #externalMacro(module: "MacroDefinition", type: "AddClassReferencingSelfMacro")

test/Macros/Inputs/syntax_macro_definitions.swift

@@ -1296,3 +1296,26 @@ public struct DefineAnonymousTypesMacro: DeclarationMacro {
     ]
   }
 }
+
+public struct AddClassReferencingSelfMacro: PeerMacro {
+  public static func expansion(
+    of node: AttributeSyntax,
+    providingPeersOf declaration: some DeclSyntaxProtocol,
+    in context: some MacroExpansionContext
+  ) throws -> [DeclSyntax] {
+    guard let protocolDecl = declaration.as(ProtocolDeclSyntax.self) else {
+      throw CustomError.message("Macro can only be applied to a protocol declarations.")
+    }
+
+    let className = "\(protocolDecl.identifier.text)Builder"
+    return [
+      """
+      struct \(raw: className) {
+       init(_ build: (_ builder: Self) -> Self) {
+         _ = build(self)
+       }
+      }
+      """
+    ]
+  }
+}

test/Macros/macro_expand_peers.swift

@@ -25,6 +25,8 @@ import macro_library
 #else
 @attached(peer, names: overloaded)
 macro addCompletionHandler() = #externalMacro(module: "MacroDefinition", type: "AddCompletionHandler")
+@attached(peer, names: suffixed(Builder))
+macro AddClassReferencingSelf() = #externalMacro(module: "MacroDefinition", type: "AddClassReferencingSelfMacro")
 #endif
 
 struct S {
@@ -113,3 +115,6 @@ struct Main {
     // CHECK-EXEC: hahaha global
   }
 }
+
+@AddClassReferencingSelf
+protocol MyProto { }